tag:blogger.com,1999:blog-38042245434111190832024-03-13T14:18:29.943-04:00Air Pollution, Aerosols and Clouds in the Climate SystemWelcome to the world of atmospheric aerosols, clouds and climate science. Atmospheric aerosols (or PM) are complex mixture of solid and liquid particles that vary in size and composition, and remain suspended in the air. They affect human health and play an important role in weather and climate change processes. Due to high temporal and spatial variability, their characterization into climate models is highly uncertain. This blog is our science diary about latest research in this field.Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.comBlogger65125tag:blogger.com,1999:blog-3804224543411119083.post-26918167362058727742012-04-18T11:45:00.003-04:002012-04-18T11:46:06.170-04:00Air Quality Monitoring from Space<div dir="ltr" style="text-align: left;" trbidi="on">
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<strong><span class="style1" style="font-size: medium;">Special Issue of Atmospheric Pollution Research (APR) on “Air Quality Monitoring from Space”</span></strong></div>
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<span style="text-align: justify;">This special issue will be
focused on surface air quality monitoring and forecasting using surface and
satellite observations of aerosols and trace gases over regional to global
scales. In recent years, satellite observations of aerosols and trace gases have
shown potential for application to monitor surface air quality with high
spatial and temporal resolution over regional to global scales. Authors are
encouraged to submit contributions that describe original research results of
studies conducted using satellite derived aerosols and trace gases product for monitoring as well as estimation and forecasting of PM</span><sub style="text-align: justify;">2.5</sub><span style="text-align: justify;">, PM</span><sub style="text-align: justify;">10</sub><span style="text-align: justify;">, Ozone, NO</span><sub style="text-align: justify;">x</sub><span style="text-align: justify;">, and SO</span><sub style="text-align: justify;">2</sub><span style="text-align: justify;"> </span><span style="text-align: justify;">at the surface. Topics will include (but are not
limited to): particulate matter observations from space and surface, regional
trends of air quality parameters, assimilation of satellite data of aerosols
into air quality and regional atmospheric models, transport of aerosols, role
of biomass burning and dust aerosols in local air quality, role of local
meteorology in estimation of PM</span><sub style="text-align: justify;">2.5</sub><span style="text-align: justify;"> </span><span style="text-align: justify;">from satellite observations, boundary layer
process and their impact on satellite observations, and physical and
statistical modeling of air quality, population health and ecological impact
assessments driven by satellite data.</span><span style="line-height: 18px; text-align: justify;"> </span></div>
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for more details -- please check the following link<br />
<a href="http://www.atmospolres.com/special.html">http://www.atmospolres.com/special.html</a>
</div>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-44827531804246002872011-07-27T04:20:00.005-04:002011-07-27T04:43:08.713-04:00Which station has longest continuous time series of aerosol related observations?Sometime I wonder are there any questions left which Google can not answer? Today I stumble upon one such question, when I was just curious to know which station is oldest running station for aerosol related observations? I know in Barrow,Alaska and South Pole, <a href="http://www.esrl.noaa.gov/gmd/">CMDL</a> is monitoring AOD since 1977. But don't know whether these are the oldest stations. And what about black carbon, surface size distribution, PM10, scattering coefficient. I guess one can expect to get long-time series for PM10 at least. <br /><br />Let us compile the list. Leave the name of station and time period in comment, you know for aerosol related obs. are being made from the station.Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com3tag:blogger.com,1999:blog-3804224543411119083.post-91997037543778517272010-09-25T11:42:00.002-04:002010-09-25T11:44:23.772-04:00Air Pollution Raises Risk of Sudden Cardiac Arrest: Study --Doctors LoungeOne more reason to study aerosols. See an interesting article on Doctor's Lounge. <br /><br /><a href="http://www.doctorslounge.com/index.php/news/hd/14292">Air Pollution Raises Risk of Sudden Cardiac Arrest: Study --Doctors Lounge</a>Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com7tag:blogger.com,1999:blog-3804224543411119083.post-54958134799185409792010-07-27T16:48:00.000-04:002010-07-27T16:49:09.153-04:00Aerosols can only temporary fix global warming<div>an interesting article</div><div><br /></div>http://timesofindia.indiatimes.com/home/environment/global-warming/Aerosols-can-only-temporary-fix-global-warming-/articleshow/6187668.cmsPawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com3tag:blogger.com,1999:blog-3804224543411119083.post-34519687047222378812010-05-16T02:21:00.009-04:002010-05-28T03:33:23.639-04:00A Smog Blog by NASAI remember an incident from early days of my PhD. I was travelling in a train and a fellow passenger asked me what is that I am doing? My reply was, "I study aerosols for their climatic effects". He was thoroughly confused. What he understood from the word "aerosol" was that I am studying gases coming out of aerosol-cans affecting the ozone layer. It was not his fault. There are very few places where aerosols scientist interact with laymen about their research. I guess still the situation may be not be very different from the perspective of layman when he or she hears word "aerosol". Beside aerosol's climatic effects, laymen have many reasons to know about aerosols, if not for the sack of curiosity, for the sack of his/her health. The obvious question is where to get this information particularly in a format that a layman can understand and use it without further processing it. <br /><br />Few scientists and students from University of Maryland, Baltimore county have created a blog with the support of NASA to fill this information gap. They have named it "<a href="http://alg.umbc.edu/usaq/">Smog Blog</a>". Find out more about this blog from a video that NASA has created to popularize <span style="font-weight:bold;">The Smog Blog</span>. <br /><object width="560" height="340"><param name="movie" value="http://www.youtube.com/v/vIp3tuYRFDE&hl=en_US&fs=1&rel=0"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/vIp3tuYRFDE&hl=en_US&fs=1&rel=0" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="560" height="340"></embed></object><br /><br />Link to Smog Blog<br /><a href="http://alg.umbc.edu/usaq/">http://alg.umbc.edu/usaq/</a><br /><br />Link to NASA video about Smog Blog<br /><a href="http://www.nasa.gov/topics/earth/features/smogblog.html">http://www.nasa.gov/topics/earth/features/smogblog.html</a>Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com2tag:blogger.com,1999:blog-3804224543411119083.post-40754424941007991182010-01-17T15:02:00.002-05:002010-01-17T15:13:15.040-05:00Conference: AOGS, 5-9 July 2010, Hyderabad, India<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://www.igu.in/images/AOGS--Page.jpg"><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 595px; height: 828px;" src="http://www.igu.in/images/AOGS--Page.jpg" border="0" alt="" /></a><br /><div>Asia Oceanic Geosciences Society will be organizing its 7th Annual Meeting in Hyderabad, India during July 5-9, 2010.</div><div><br /></div><div>For more conference details <a href="http://www.asiaoceania.org/aogs2010/index.asp">click here</a> </div><div><br /></div><div>During this conference, we are hosting a special session on Atmospheric aerosols and their impact on climate and air quality. Please consider contributing to this session. </div><div><br /></div><div>The deadline for abstract submission is March 1, 2010.</div><div><br /></div><div><b>Session Description</b></div><br /><div><span class="Apple-style-span" style=" ;font-family:Arial, Tahoma, Helvetica, sans-serif;font-size:12px;"><table width="100%" style="font-family: Arial, Tahoma, Helvetica, sans-serif; "><tbody style="font-family: Arial, Tahoma, Helvetica, sans-serif; "><tr style="font-family: Arial, Tahoma, Helvetica, sans-serif; "><td style="font-family: Arial, Tahoma, Helvetica, sans-serif; font-size: 9pt; ">Section</td><td style="font-family: Arial, Tahoma, Helvetica, sans-serif; font-size: 9pt; ">AS - Atmospheric Science </td></tr><tr bgcolor="#EEEEFF" style="font-family: Arial, Tahoma, Helvetica, sans-serif; "><td width="25%" style="font-family: Arial, Tahoma, Helvetica, sans-serif; font-size: 9pt; ">Session Title</td><td width="75%" style="font-family: Arial, Tahoma, Helvetica, sans-serif; font-size: 9pt; "><b style="font-family: Arial, Tahoma, Helvetica, sans-serif; ">Measurement and Modeling of Atmospheric Aerosols for Climate and Air Quality Applications</b></td></tr></tbody></table></span><div><br /></div><div><span class="Apple-style-span" style=" ;font-family:Arial, Tahoma, Helvetica, sans-serif;font-size:12px;"><table width="100%" style="font-family: Arial, Tahoma, Helvetica, sans-serif; "><tbody style="font-family: Arial, Tahoma, Helvetica, sans-serif; "><tr style="font-family: Arial, Tahoma, Helvetica, sans-serif; "><td valign="top" style="font-family: Arial, Tahoma, Helvetica, sans-serif; font-size: 9pt; ">Session Description</td><td valign="top" class="mini" style="font-family: Arial, Tahoma, Helvetica, sans-serif; font-size: 8pt; ">The ever-growing population and human activities have led to a rapid and continuous increase in the emission of aerosols and its precursor gases in past several decades. Advancement in aerosol measurements and modeling capabilities in last two decades provides an opportunity to investigate the impact of anthropogenic activities on air quality, solar energy, regional and global climate and hydrological cycle. This session is concerned primarily with aerosols measurements and their application to climate and air quality over global regions. This includes, measurement techniques, data analysis, seasonal and long term trends, ground and space based remote sensing, aerosols and climate, observations related to air quality, use of satellite data for particulate matter monitoring, aerosol model development, model validation using ground and satellite data, assimilation of satellite products into regions and community air quality models. Also include emission of aerosols and its precursors, aerosol properties and radiative effects, aerosol-cloud-precipitation interactions, regional climatic and hydrological effects of aerosol, and impact of climate change and variability on aerosol. Original studies using long-term ground observations, data from field campaigns, satellite measurements, and models are also solicited.</td></tr></tbody></table></span></div></div>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com1tag:blogger.com,1999:blog-3804224543411119083.post-1844951524754528312009-12-15T13:16:00.001-05:002009-12-15T13:17:17.275-05:00AGU Fall Meeting 2009 – Day 1 – Aerosols Talks and Poster<!--StartFragment--> <p class="MsoNormal" style="text-align: justify;">Well, as usual, the first day of the AGU meeting was very hectic, running around the sessions. All of the posters on aerosols had overwhelmingly important and interesting research. I had a poster in data fusion session where I presented aerosols optical depth products inter-comparison from multiple sensors during a field campaign in Saharan desert. I had a good discussion with Omar and Hiren about improvement in OMI aerosol product after introducing more spectral dependence of absorption. Jethva also had a poster, which demonstrated this new improved product for smoke aerosols. Lorraine Remer from GSFC presented a poster on possible inclusion of PARASOL and CALIPSO data sets into future MODIS aerosols product files. It will be very useful to have PARASOL AODs within MODIS files, which is more sensitive to fine mode aerosols. There was also a poster by Y. Shi along with Jeff Reid and J. Zhang analyzing uncertainties in MODIS and MISR over global regions and ways of correcting it for aerosols data assimilation into NAAPS.<span style="mso-spacerun: yes"> </span>There was also a poster by Salustro showing validation of Deep Blue product over bight targets. According to Salustro, Deep Blue will be available for all cases starting collection 6 MODIS data sets. I like the talk by Jeff Reid talking about considering various biases while utilizing multi sensor satellite data sets for assimilation and climate applications.<br /></p> <!--EndFragment-->Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com1tag:blogger.com,1999:blog-3804224543411119083.post-23778368580402766932009-12-03T23:56:00.005-05:002009-12-04T03:18:39.972-05:00What is Carbon Trading?Well, this is not exactly the aerosol related post. However, reducing carbon dioxide by incorporating newer technology will have side effect (of cause good) of reducing atmospheric aerosols, after all aerosols and carbon dioxide have more less similar source namely vehicular emissions, coal based power plants, etc. However, million dollar question is how society plans to pursue people and industry for reducing carbon dioxide emissions at global scale. One of the ways, politicians and economist come-up with is carbon trading. What is carbon trading? Can it achieve its stated objective? There are different opinions about it. Let us see one of the opinions in this video. Do you remember movie "<a href="http://www.storyofstuff.org/">Story of the Stuff</a>", if yes then well this video is from same people. <br /><br /><object width="400" height="205"><param name="allowfullscreen" value="true" /><param name="allowscriptaccess" value="always" /><param name="movie" value="http://vimeo.com/moogaloop.swf?clip_id=7908590&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1" /><embed src="http://vimeo.com/moogaloop.swf?clip_id=7908590&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" width="400" height="205"></embed></object><p><a href="http://vimeo.com/7908590">The Story of Cap & Trade</a> from <a href="http://vimeo.com/storyofstuff">Story of Stuff Project</a> on <a href="http://vimeo.com">Vimeo</a>.</p>Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-76778331242281901232009-11-26T11:28:00.003-05:002009-12-04T03:13:53.827-05:00Potential impact of U.S. biofuels on regional climate<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://2.bp.blogspot.com/_hkgyfXKGPaA/Sw6teTR0vOI/AAAAAAAAKkM/IN8b7P5N00M/s1600/30949-Clipart-Illustration-Of-A-Yellow-Gas-Nozzle-Emerging-From-A-Yellow-Corn-Biofuel-Pump.jpg"><img style="float:left; margin:0 10px 10px 0;cursor:pointer; cursor:hand;width: 400px; height: 320px;" src="http://2.bp.blogspot.com/_hkgyfXKGPaA/Sw6teTR0vOI/AAAAAAAAKkM/IN8b7P5N00M/s400/30949-Clipart-Illustration-Of-A-Yellow-Gas-Nozzle-Emerging-From-A-Yellow-Corn-Biofuel-Pump.jpg" border="0" alt="" id="BLOGGER_PHOTO_ID_5408450938601258210" /></a><p class="MsoNormal" style="text-align:justify">Recently, I came across this nice article published in JGR, which talks about impact of using biofuels on regional climate in the <st1:country-region st="on"><st1:place st="on">United States</st1:place></st1:country-region>. The debate on using biofuels for future energy needs is on.</p><p class="MsoNormal" style="text-align:justify"><b></b></p><b><p class="MsoNormal"><span class="Apple-style-span" style="font-weight: 800; ">Abstract reads as</span></p> <p class="MsoNormal" style="text-align:justify"><span class="Apple-style-span" style="font-weight: normal;">“</span><span class="apple-style-span"><span style="color:black;"><span class="Apple-style-span" style="font-weight: normal;">Recent work has shown that current bio-energy policy directives may have harmful, indirect consequences, affecting both food security and the global climate system. An additional unintended but direct effect of large-scale biofuel production is the impact on local and regional climate resulting from changes in the energy and moisture balance of the surface upon conversion to biofuel crops. Using the latest version of the WRF modeling system we conducted twenty-four, midsummer, continental-wide, sensitivity experiments by imposing realistic biophysical parameter limits appropriate for bio-energy crops in the Corn Belt of the </span><st1:country-region st="on"><st1:place st="on"><span class="Apple-style-span" style="font-weight: normal;">United States</span></st1:place></st1:country-region><span class="Apple-style-span" style="font-weight: normal;">. In the absence of strain/crop-specific parameterizations, a primary goal of this work was to isolate the maximum regional climate impact, for a trio of individual July months, due to land-use change resulting from bio-energy crops and to identify the relative importance of each biophysical parameter in terms of its individual effect. Maximum, local changes in 2 m temperature of the order of 1°C occur for the full breadth of albedo (ALB), minimum canopy resistance (RC</span><sub><span class="Apple-style-span" style="font-weight: normal;">MIN</span></sub><span class="Apple-style-span" style="font-weight: normal;">), and rooting depth (ROOT) specifications, while the regionally (105°W–75°W and 35°N–50°N) and monthly averaged response of 2 m temperature was most pronounced for the ALB and RC</span><sub><span class="Apple-style-span" style="font-weight: normal;">MIN</span></sub></span></span><span class="apple-converted-space"><span style="color:black;"><span class="Apple-style-span" style="font-weight: normal;"> </span></span></span><span class="apple-style-span"><span style="color:black;"><span class="Apple-style-span" style="font-weight: normal;">experiments, exceeding 0.2°C. The full range of albedo variability associated with biofuel crops may be sufficient to drive regional changes in summertime rainfall. Individual parameter effects on 2 m temperature are additive, highlight the cooling contribution of higher leaf area index (LAI) and ROOT for perennial grasses (e.g., Miscanthus) versus annual crops (e.g., maize), and underscore the necessity of improving location- and vegetation-specific representation of RC</span><sub><span class="Apple-style-span" style="font-weight: normal;">MIN</span></sub></span></span><span class="apple-converted-space"><span style="color:black;"><span class="Apple-style-span" style="font-weight: normal;"> </span></span></span><span class="apple-style-span"><span style="color:black;"><span class="Apple-style-span" style="font-weight: normal;">and ALB”</span></span></span></p> <p class="MsoNormal">Complete Reference</p> <p class="MsoNormal" style="text-align: left;"><a href="http://www.agu.org/pubs/crossref/2009/2009GL040477.shtml"><span class="Apple-style-span" style="font-weight: normal;">Georgescu, M., D. B. Lobell, and C. B. Field (2009), Potential impact of U.S. biofuels on</span><span class="Apple-style-span" style="font-weight: normal;"><o:p></o:p></span></a><span class="Apple-style-span" style="font-weight: normal;"> </span><span class="MsoHyperlink"><a href="http://www.agu.org/pubs/crossref/2009/2009GL040477.shtml"><span class="Apple-style-span" style="font-weight: normal;">regional climate, Geophys. Res. Lett., 36, L21806, doi:10.1029/2009GL040477</span></a></span><span class="Apple-style-span" style="font-weight: normal;">.</span></p> <p class="MsoNormal"><span class="Apple-style-span" style="font-weight: 800; ">Read about different aspects of biofuels</span></p> <p class="MsoNormal"><a href="http://bio-fuel-watch.blogspot.com/"><span class="Apple-style-span" style="font-weight: normal;">http://bio-fuel-watch.blogspot.com/</span></a></p></b><p></p>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com1tag:blogger.com,1999:blog-3804224543411119083.post-79760244852748620242009-10-30T10:19:00.004-04:002009-12-04T03:13:07.550-05:00Satellite Observation of Fires in Indian Oil Depot<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://3.bp.blogspot.com/_hkgyfXKGPaA/Sur2PKP-KrI/AAAAAAAAKhk/9V-NrqK7x9g/s1600-h/modis-fires-IOD-gupta.jpg"><br /><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 400px; height: 262px;" src="http://3.bp.blogspot.com/_hkgyfXKGPaA/Sur2PKP-KrI/AAAAAAAAKhk/9V-NrqK7x9g/s400/modis-fires-IOD-gupta.jpg" border="0" alt="" id="BLOGGER_PHOTO_ID_5398397843666774706" /></a><p class="MsoNormal" style="text-align:justify">India Oil Depot caught fire on October 29, 2009 at around 7:30 pm local time. This depot is located about 10 miles south of the Indian pink city Jaipur in the state of Rajasthan. Fire is so massive that the entire area is covered by black smoke clouds. Smoke and haze are visible up to 16 miles away from the fire location. This image is taken by NASA’s MODIS onboard EOS Aqua satellite on October 30, 2009 during its pass over <st1:country-region st="on"><st1:place st="on">India</st1:place></st1:country-region>. </p> <p class="MsoNormal" style="text-align:justify"><o:p>Original data for the image is taken from NASA’s MODIS Rapid Fire System and processed at <st1:placetype st="on">University</st1:placetype> of <st1:placename st="on">Alabama</st1:placename> in <st1:place st="on"><st1:city st="on">Huntsville</st1:city>, <st1:state st="on">AL</st1:state></st1:place>.</o:p></p> <p class="MsoNormal" style="text-align:justify"><o:p>For more news on fire</o:p></p> <p class="MsoNormal" style="text-align:justify"><a href="http://news.bbc.co.uk/2/hi/south_asia/8333211.stm">http://news.bbc.co.uk/2/hi/south_asia/8333211.stm</a></p>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-37587371689697183532009-10-14T20:55:00.006-04:002009-10-14T21:08:44.953-04:00New Online Open Access Earth Science Journal – Blog Action Day Post<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://1.bp.blogspot.com/_hkgyfXKGPaA/StZ18hSKm_I/AAAAAAAAKfk/lKxo6OJrae8/s1600-h/blog-oct15-image.jpg"><img style="text-align: justify;display: block; margin-top: 0px; margin-right: auto; margin-bottom: 10px; margin-left: auto; cursor: pointer; width: 316px; height: 320px; " src="http://1.bp.blogspot.com/_hkgyfXKGPaA/StZ18hSKm_I/AAAAAAAAKfk/lKxo6OJrae8/s320/blog-oct15-image.jpg" border="0" alt="" id="BLOGGER_PHOTO_ID_5392627286409911282" /></a><div style="text-align: center;"><span class="Apple-style-span" style="color: rgb(34, 34, 34); "><div style="text-align: center;"><span class="Apple-style-span" style="color: rgb(0, 0, 0); font-family: arial, sans-serif; border-collapse: collapse; "><span class="Apple-style-span" style="font-size: medium;"><a href="http://www.blogactionday.org/" target="_blank" style="color: rgb(0, 0, 204); ">www.blogactionday.org</a></span></span></div><div style="text-align: center;"><span class="Apple-style-span" style="font-family:arial, sans-serif;color:#000000;"><span class="Apple-style-span" style="border-collapse: collapse; font-size: medium;"><br /></span></span></div></span></div><div style="text-align: justify;"><span class="Apple-style-span" style="color: rgb(34, 34, 34); "><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Earth and Information technology scientists at the </span></span><st1:placetype st="on"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">University</span></span></st1:placetype><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;"> of </span></span><st1:placename st="on"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Alabama</span></span></st1:placename><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;"> in </span></span><st1:city st="on"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Huntsville</span></span></st1:city><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;"> and at the </span></span><span class="apple-style-span"><span style="color:black;"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Caelum Research Corporation, </span></span><st1:city st="on"><st1:place st="on"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Rockville </span></span></st1:place></st1:city></span></span><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">introduced a new online free access earth science journal, where short articles discussing various earth science phenomena can be published. The journal is open to everybody including students, researcher and scientists. I would recommend earth science students who would like to start on publishing their work, JESP is great place to start. It does not take lot of efforts to compose article for this journal, but make sure contains of article are scientifically sound.</span></span></span></div><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://2.bp.blogspot.com/_hkgyfXKGPaA/StZzi9Yi9-I/AAAAAAAAKfU/6mIqcJKvZI8/s1600-h/blog-oct15-image.jpg"></a> <p class="MsoNormal" style="text-align:justify"><span class="apple-style-span"><span style="color:#222222;"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Below is description as given on their webpage.</span></span><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;"><o:p></o:p></span></span></span></span></p> <p class="MsoNormal" style="text-align:justify"><span class="apple-style-span"><span style="color:#222222;"><o:p><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;"> </span></span><span class="Apple-style-span" style="color: rgb(0, 0, 0); "><span class="apple-style-span"><span style="color:#222222;"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">“Journal of Earth Science Phenomena (JESP) is an open access journal aimed at publishing</span></span></span></span><span class="apple-converted-space"><span style="color:#222222;"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;"> </span></span></span></span><span class="apple-style-span"><span style="color:#222222;"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">micro-articles</span></span></span></span><span class="apple-converted-space"><span style="color:#222222;"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;"> </span></span></span></span><span class="apple-style-span"><span style="color:#222222;"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">cataloging interesting and unique phenomena that are observed in Earth science data. The primary aim of this journal is not to report a detailed scientific analysis, but to promote further enquiry, document unique phenomena, assist educational activities and compile the information in a manner that is both searchable and citable. The online nature of the journal also provide for including geographic context, linkages to other geospatial information through Google Earth Technology and also explicit references to online databases where such information could be retrieved.”</span></span></span></span></span></o:p></span></span></p> <p class="MsoNormal" style="text-align:justify"><span class="apple-style-span"><span style="color:#222222;"><o:p><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Blog Action Day Post</span></span></o:p></span></span></p><p class="MsoNormal" style="text-align:justify"><span class="apple-style-span"><span style="color:#222222;"><o:p><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">Link to the journal</span></span></o:p></span></span></p> <p class="MsoNormal" style="text-align:justify"><a href="http://esphenomena.com/"><span class="Apple-style-span" style="font-family:georgia;"><span class="Apple-style-span" style="font-size:medium;">http://esphenomena.com/</span></span></a></p>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com1tag:blogger.com,1999:blog-3804224543411119083.post-39951545786577740762009-09-19T10:48:00.004-04:002009-09-19T10:54:48.010-04:00Remote Sensing of Particulate Pollution: Satellite Prospective<p class="MsoNormal" style="text-align:justify">Satellite remote sensing of particulate matter air pollution has shown tremendous potential for air quality monitoring over global regions with advancement in research and application over very short period of less than a decade. Recently, Air & Waste Management Association (AWMA) conducted a critical review of research on particle air quality monitoring from satellite observations. Critical review is conducted by experts in the field Ray Hoff from UMBC and Sundar A. Christopher from UAHuntsville. </p> <p class="MsoNormal" style="text-align:justify"><o:p> <span class="Apple-style-span" style="font-weight: bold; ">The Abstract reads as</span></o:p></p> <p class="MsoNormal" style="text-align:justify"><br /><img src="http://4.bp.blogspot.com/_hkgyfXKGPaA/SrTwXwU6CQI/AAAAAAAAKUA/u4KykgkS5hs/s320/p5950_56e2c2eb9d1d089ee42430cf1a5889c7Calipso_migration_de_sable.jpg" style="float:left; margin:0 10px 10px 0;cursor:pointer; cursor:hand;width: 320px; height: 241px;" border="0" alt="" id="BLOGGER_PHOTO_ID_5383191745514834178" />The recent literature on satellite remote sensing of air quality is reviewed. 2009 is the 50th anniversary of the first satellite atmospheric observations. For the first 40 of those years, atmospheric composition measurements, meteorology, and atmospheric structure and dynamics dominated the missions launched. Since 1995, 42 instruments relevant to air quality measurements have been put into orbit. Trace gases such as ozone, nitric oxide, nitrogen dioxide, water, oxygen/tetraoxygen, bromine oxide, sulfur dioxide, formaldehyde, glyoxal, chlorine dioxide, chlorine monoxide, and nitrate radical have been measured in the stratosphere and troposphere in column measurements. Aerosol optical depth (AOD) is a focus of this review and a significant body of literature exists that shows that ground-level fine particulate matter (PM2.5) can be estimated from columnar AOD. Precision of the measurement of AOD is _20% and the prediction of PM2.5 from AOD is order _30% in the most careful studies. The air quality needs that can use such predictions are examined. Satellite measurements are important to event detection, transport and model prediction, and emission estimation. It is suggested that ground-based measurements, models, and satellite measurements should be viewed as a system, each component of which is necessary to better understand air quality.</p> <p class="MsoNormal" style="text-align:justify"><o:p> <span class="Apple-style-span" style=" font-weight: bold; "><span class="Apple-style-span" style="font-size:small;">Complete Reference</span></span></o:p></p> <p class="MsoNormal" style="text-align:justify"><span class="apple-style-span"><span style="color:black;"><o:p><span class="Apple-style-span" style="font-size:small;"> </span><a href="http://secure.awma.org/onlinelibrary/ProductDetails.aspx?ProductID=17177"><span class="Apple-style-span" style="font-size:small;">Hoff, R., S.A. Christopher, Remote Sensing of Particualte Matter Air Pollution from Space : Have we reached the promised land, J. Air&Waste Manage. Assoc., 59:642-675, 2009.</span></a></o:p></span></span></p>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-29146338325918620282009-09-11T10:48:00.004-04:002009-09-11T10:52:23.832-04:00Climate Uncertainty and Air Quality<p class="MsoNormal" style="text-align:justify">Interesting article on impact of climate uncertainty on regional air quality appeared in ACP earlier this year. Model simulations of the extreme climate scenarios are found to have moderate effect on predicted emissions of VOC and ozone concentration in year 2050. </p> <p class="MsoNormal" style="text-align:justify"><span class="Apple-style-span" style="font-weight: bold; ">Abstract</span></p> <p class="MsoNormal" style="text-align:justify"><o:p>Uncertainties in calculated impacts of climate forecasts on future regional air quality are investigated using downscaled MM5 meteorological fields from the NASA GISS and MIT IGSM global models and the CMAQ model in 2050 in the continental US. Differences between three future scenarios: high-extreme, low-extreme and base case, are used for quantifying effects of climate uncertainty on regional air quality. GISS, with the IPCC A1B scenario, is used for the base case simulations. IGSM results, in the form of probabilistic distributions, are used to perturb the base case climate to provide the high- and low-extreme scenarios. Impacts of the extreme climate scenarios on concentrations of summertime fourth-highest daily maximum 8-h average ozone are predicted to be up to 10 ppbV (about one-seventh of the current US ozone standard of 75 ppbV) in urban areas of the Northeast, Midwest and Texas due to impacts of meteorological changes, especially temperature and humidity, on the photochemistry of tropospheric ozone formation and increases in biogenic VOC emissions, though the differences in average peak ozone concentrations are about 1–2 ppbV on a regional basis. Differences between the extreme and base scenarios in annualized PM2.5 levels are very location dependent and predicted to range between −1.0 and +1.5μgm−3. Future annualized PM2.5 is less sensitive to the extreme climate scenarios than summertime peak ozone since precipitation scavenging is only slightly affected by the extreme climate scenarios examined. Relative abundances of biogenic VOC and anthropogenic NOx lead to the areas that are most responsive to climate change. Overall, planned controls for decreasing regional ozone and PM2.5 levels will continue be effective in the future under the extreme climate scenarios. However, the impact of climate uncertainties may be substantial in some urban areas and should be included in assessing future regional air quality and emission control requirements.</o:p></p> <p class="MsoNormal" style="text-align:justify;mso-layout-grid-align:none; text-autospace:none"><span class="Apple-style-span" style="font-weight: bold; ">Complete Reference</span></p> <p class="MsoNormal"><o:p><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">Liao, K. J.;</a><span class="apple-converted-space"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf"> </a></span><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">Tagaris, E.;</a><span class="apple-converted-space"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf"> </a></span><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">Manomaiphiboon, K.;</a><span class="apple-converted-space"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf"> </a></span><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">Wang, C.;</a><span class="apple-converted-space"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf"> </a></span><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">Woo, J.H.;</a><span class="apple-converted-space"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf"> </a></span><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">Amar, P.;</a><span class="apple-converted-space"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf"> </a></span><span style="color:windowtext;text-decoration:none;text-underline:none"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">He, S.</a></span><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">;</a><span class="apple-converted-space"><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf"> </a></span><a href="http://www.atmos-chem-phys.org/9/865/2009/acp-9-865-2009.pdf">Russell, A. G. , Quantification of the impact of climate uncertainty on regional air quality, Atmospheric Chemistry and Physics, Volume 9, Issue 3, 2009, pp.865-878</a></o:p></p>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-54425650254592620182009-08-02T10:44:00.005-04:002009-08-03T00:03:37.377-04:00Evaluating Particulate Matter Air Quality with Surface and Space-Borne Measurements<div>The special session on "A40: Evaluating Particulate Matter Air Quality with Surface and Space-Borne Measurements" is planned during coming fall AGU Meeting in San Francisco, 14-18 December, 2009. Following is the link for more details on session description.</div><br /><a class="moz-txt-link-freetext" href="http://www.agu.org/meetings/fm09/program/scientific_session_search.php?show=detail&sessid=645">http://www.agu.org/meetings/fm09/program/scientific_session_search.php?show=detail&sessid=645</a> <div> <br />Abstract submission is open now and last date is September 3, 2009.<br /><br />we would like to invite you all to contribute to the session by submitting an abstract. Please forward this information to your colleagues and students.<br /><br />Following link provides guidelines to submit the abstract.<br /><a class="moz-txt-link-freetext" href="http://www.agu.org/meetings/fm09/index.php#software">http://www.agu.org/meetings/fm09/index.php#software</a><br /><br />Thanks and hope to see your abstract soon in AGU system.</div>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-29754322904416026602009-02-10T22:42:00.016-05:002009-02-10T23:15:47.336-05:00The Cloud Makers - A video about effect of aerosols on cloudI found a very interesting video about effects of aerosols on clouds and how the GLORY mission of NASA going to address this problem. Click on the image or the link below to view the video.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://www.nasa.gov/mp4/266583main_TheCloudMakers.mp4"><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 200px; height: 150px;" src="http://1.bp.blogspot.com/_JMOQWjQG5JU/SZJJ9-01iII/AAAAAAAAFVU/E2vGq3aNDgA/s200/aerosols2.jpg" border="0" alt="Microscopic image of aerosols"id="BLOGGER_PHOTO_ID_5301381040553953410" /></a><br /><br /><a href="http://www.nasa.gov/mp4/266583main_TheCloudMakers.mp4"> Play video "The Cloud Makers"</a><br /><br />Image courtesy: NASA Goddard Space Flight CenterAnonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-23634249713771265662008-10-04T10:41:00.009-04:002008-10-04T11:14:25.186-04:00Long Range Transport of Dust Aerosols<div><br />Continuing from our last blog post on the issue of aerosol radiative forcing (ARF) and the importance of its vertical distribution, l would like to bring to attention another important aspect associated with aerosols that affect global ARF. This aspect is the transport of aerosols which is very closely related to its vertical distribution. One of the largest sources of aerosols is desert. These desert dust aerosols have gained much attention due to the long range transport associated with them. The dust from these deserts is lifted higher in the atmosphere and ‘because of the fast large-scale transport in the upper troposphere, aerosols such as dust and black carbon, once they enter the upper troposphere (above ~8 km), can be transported around the earth in a latitudinal belt in a week or two’. ‘The impact of long range transport of dust and air pollution from their continental sources over oceanic regions is one of the outstanding problems in understanding regional and global climate change’ and in also determining the air quality of regions to which dust is advected to. Using Calipso and surface micropulse lidar, Huang et al., [2008] observe the long-range transport and vertical distribution of Asian dust aerosols during the PACific Dust EXperiment (PACDEX). ‘The MPL measurements were made at the Loess Plateau (35.95°N, 104.1°E) near the major dust source regions of the Taklamakan and Gobi Deserts’ in China during March-May 2007. They find that ‘Dust events were more frequent in the Taklamakan, where floating dust dominates, while more intensive, less frequent dust storms were more common in the Gobi region. The vertical distribution of the CALIPSO backscattering/depolarization ratios indicate that non-spherically shaped dust aerosols floated from near the gr<a href="http://4.bp.blogspot.com/_LqpLbbo4dRk/SOeIH7srFNI/AAAAAAAABRY/ND9cZulNOgM/s1600-h/NewPicture.jpg"><img id="BLOGGER_PHOTO_ID_5253317160216499410" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; CURSOR: hand" alt="" src="http://4.bp.blogspot.com/_LqpLbbo4dRk/SOeIH7srFNI/AAAAAAAABRY/ND9cZulNOgM/s320/NewPicture.jpg" border="0" /></a>ound to an altitude of approximately 9 km around the source regions. This suggests the possible long-range transport of entrained dus<a href="http://4.bp.blogspot.com/_LqpLbbo4dRk/SOeHkiEkcrI/AAAAAAAABRQ/riwajkjquik/s1600-h/NewPicture.jpg"></a>t aerosols via upper tropospheric westerly jets. A very distinct large depolarization layer was also identified between 8 and 10 km over eastern China and the western Pacific Ocean corresponding to dust aerosols transported from the Taklamakan and Gobi areas, as confirmed by back trajectory analyses. The combination of these dust sources results in a two-layer or multilayered dust structure over eastern China and the western Pacific Ocean.’ We have seen in our last blog spot that ‘the vertical distribution of dust aerosols is another critical factor impacting the effects of dust on radiative forcing and climate [Claquin et al., 1998; Zhu et al., 2007; Forster et al., 2007].<br /><br /><strong>References:</strong><br /><br /><a href="http://www.agu.org/journals/pip/jd/2008JD010620-pip.pdf">Huang, J., P. Minnis, B. Chen, Z. Huang, Z. Liu, Q. Zhao, Y. Yi, and J. Ayers (2008), Long-range Transport and Vertical Structure of Asian Dust from CALIPSO and Surface Measurements during PACDEX, J. Geophys. Res., doi:10.1029/2008JD010620, in press. </a><br /><br />Claquin, T., M. Schulz, Y. J. Balkanski, and O. Boucher (1998), Uncertainties in assessing radiative forcing by mineral dust, Tellus, Ser. B, 50, 491–505.<br /><br />Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn,G. Raga, M. Schulz and R. Van Dorland (2007), Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.<br /><br />Zhu, A., V. Ramanathan, F. Li, and D. Kim (2007), Dust plumes over the Pacific, Indian, and Atlantic oceans: Climatology and radiative impact, J. Geophys. Res., 112, D16208, doi:10.1029/2007JD008427 </div>Falguni Patadiahttp://www.blogger.com/profile/12631993863421082267noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-43242780010789828322008-09-20T17:26:00.015-04:002008-09-22T05:49:00.792-04:00Impact of Aerosol Vertical Distribution on their Radiative Effects<div align="justify">From over a decade of aerosol research, it is now a well established fact that atmospheric aerosols play a crucial role in altering the earth's radiation budget [<a href="http://www.ipcc.ch/">IPCC</a> 2007]. Toa large extent, the effect on aerosols on the top-of-atmosphere radiation balance has been addressed using both observations and global models. A close review of literature suggests the imperative need to address the vertical distribution of aerosols in the atmosphere [<a href="http://www.ann-geophys.net/24/2461/2006/angeo-24-2461-2006.html">Gadhavi et al., 2006</a>] and that is exactly what aerosol science is gearing towards. Recently, there have been many research studies that have begun to address this question. One interesting paper by Johnson et al., appeared in JGR last week that talks about this very issue.<br /><br />This paper provides very good insights into this topic by using ground and aircraft based lidar observations during <a href="http://badc.nerc.ac.uk/data/dabex/">DABEX</a> field campaign. 'In general, mineral dust was observed at low altitudes (up to 2 km), and a mixture of biomass burning aerosol and dust was observed at altitudes of 2–5 km.' </div><p> </p><p><img style="margin: 0px auto 10px; text-align: center; display: block;" id="BLOGGER_PHOTO_ID_5248242543893420002" alt="" src="http://1.bp.blogspot.com/_LqpLbbo4dRk/SNWAyYvcF-I/AAAAAAAABRI/iKuh-KQ-VLY/s320/2008jd009848-op05.jpg" border="0" /><br />For clear sky conditions, when the observed low-level dust layer was included in a radiative transfer model, the absorption of solar radiation by the biomass burning aerosols increased by 10%.' This enhancement in absorption is due to reflection of solar radiation by dust aerosols in background up into the biomass burning aerosol layer above. This situation is analogous to presence absorbing aerosols over a bright background. Thus, depending on the distribution of aerosols and the type of aerosols present at different heights in the atmosphere, their radiative effects can be altered. This in-turn changes the differential heating of the atmosphere and hence the atmospheric stability that influences convective and turbulent motions and clouds [Ackerman et al., 2000]. This can be important for both TOA and surface radiation budget. The scenario is a little more complex when aerosols are above clouds. 'For example, the elevation of biomass burning aerosols above marine stratocumulus clouds during the Southern African Regional Science Initiative (<a href="http://daac.ornl.gov/S2K/historical_UVA_edited/index.html">SAFARI-2000</a>) greatly enhanced their absorption of shortwave radiation. This led to a positive direct aerosol shortwave radiative effect over the Southern Atlantic, whereas the effect was negative in clear sky conditions [Keil and Haywood, 2003; Abel et al., 2005; Myhre et al., 2003a]'. Thus, the need to consider the treatment and appropriate representation of vertical distribution of aerosol species in the global models when estimating the impact of anthropogenic absorbing aerosols is crucial.<br /><br /></p><br /><div align="justify">Please refer to the paper by Johnson et al (below) for all references in this blog-post:</div><br /><div align="justify"></div><br /><div align="justify">Johnson, B. T., B. Heese, S. A. McFarlane, P. Chazette, A. Jones, and N. Bellouin (2008), Vertical distribution and radiative effects of mineral dust and biomass burning aerosol over West Africa during DABEX, J. Geophys. Res., 113, D00C12, doi:<a href="http://dx.doi.org/10.1029/2008JD009848">10.1029/2008JD009848 </a></div>Falguni Patadiahttp://www.blogger.com/profile/12631993863421082267noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-89909120282757533552008-06-23T03:10:00.014-04:002008-06-24T00:45:59.889-04:00Principal components analysis (PCA) for source identificationSource identification for atmospheric aerosol is important for developing effective strategy to reduce their emissions. One of the methods for source identification is principal components analysis (PCA). My attention was drawn to this method recently first through <a id="quvw" title="a review article" href="http://dx.doi.org/10.1016/j.jaerosci.2008.05.007" target="_blank">a review article</a> about methods and results for aerosol source apportionment over European region and then through the article “<a id="f:3b" title="Identification of PM sources by principal component analysis (PCA) coupled with wind direction" href="http://dx.doi.org/10.1016/j.chemosphere.2006.04.060" target="_blank">Identification of PM sources by principal component analysis (PCA) coupled with wind direction</a> ”. Dr. <a id="uq9w" title="Viana Rodríguez, Mª del Mar" href="http://www.ija.csic.es/eng/personal.php?id=83" target="_blank">Viana Rodríguez, Mª del Mar</a> is the lead author on both the articles . She is a researcher at the <a id="fxtj" title="Institute of Earth Sciences Jaume Almera" href="http://www.ija.csic.es/eng/benvinguts.php" target="_blank">Institute of Earth Sciences Jaume Almera</a>, Spain. <p class="western" id="r.8.10" style="margin-bottom: 0in;">Application of the <a id="r9eq" title="principal component analysis" href="http://en.wikipedia.org/wiki/Principal_component_analysis" target="_blank">principal components analysis</a> method for aerosol is based on the foundation that each source has unique blending of various aerosol components. Variability of the components is strongly correlated among themselves when they are coming from same source when compared to a case where they are coming from heterogeneous sources. Mathematically, PCA seeks to determine matrices A and S in the equation C=A∙S, where column matrix C represents concentration of various particulate matter (PM) components, S is the source contribution and A is the source profiles.<br /></p><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://spreadsheets.google.com/pub?key=pGmQcyLIILjeTEZcFrL34CA&oid=1&output=image"><img style="margin: 0pt 10px 10px 0pt; float: left; width: 200px; cursor: pointer;" alt="" src="http://spreadsheets.google.com/pub?key=pGmQcyLIILjeTEZcFrL34CA&oid=1&output=image" border="0" /></a> <p class="western" id="r.8.13" style="margin-bottom: 0in;">The article Viana et al. (2006) is more about results obtained using PCA analysis rather than the method itself. I liked the article for its clear conclusions and bold figures. I think figure 1 will be useful for those who are interested in knowing typical combination of various aerosol sources for given total mass. <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://spreadsheets.google.com/pub?key=pGmQcyLIILjeTEZcFrL34CA&oid=2&output=image"><img style="margin: 0pt 0pt 10px 10px; float: right; width: 200px; cursor: pointer;" alt="" src="http://spreadsheets.google.com/pub?key=pGmQcyLIILjeTEZcFrL34CA&oid=2&output=image" border="0" /></a>Figure 4 will be very useful for the people of the town <a id="jo:u" title="Llodio" href="http://en.wikipedia.org/wiki/Llodio" target="_blank">Llodio</a>, for knowing where to look for reducing pollution. I have recreated images for quick look using data from the manuscript.</p><p class="western" id="r.8.14" style="margin-bottom: 0in;"></p><p class="western" id="r.8.16" style="margin-bottom: 0in;">References:</p><p class="western" id="r.8.17" style="margin-bottom: 0in;">Viana, M., et al., (<i id="qenq">In Press</i>), <a id="qnpx" title="Source apportionment of particulate matter in europe: A review of methods and results." href="http://dx.doi.org/10.1016/j.jaerosci.2008.05.007">Source apportionment of particulate matter in europe: A review of methods and results,</a> <i id="qenq0">Journal of Aerosol Science</i><i id="qenq1">, Accepted Manuscript</i>.</p><p class="western" id="r.8.17" style="margin-bottom: 0in;">Viana, M., X. Querol, A. Alastuey, J. I. Gil, and M. Menéndez (2006, December),<a id="lxr-" title="Identification of pm sources by principal component analysis (pca) coupled with wind direction data" href="http://dx.doi.org/10.1016/j.chemosphere.2006.04.060">Identification of pm sources by principal component analysis (pca) coupled with wind direction data</a>, <i id="nqcl">Chemosphere </i><i id="nqcl0">65 </i>(11), 2411-2418.</p>Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com1tag:blogger.com,1999:blog-3804224543411119083.post-38212623232441146512008-02-24T13:49:00.003-05:002008-12-09T16:25:45.177-05:00Aerosol Radiative Effects over Global Land: A Satellite based Study<div align="justify"><a href="http://3.bp.blogspot.com/_hkgyfXKGPaA/R8G8sLPH2oI/AAAAAAAADdQ/MVu18TZlryE/s1600-h/2007gl032314-op01.jpg"><img id="BLOGGER_PHOTO_ID_5170621314314525314" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; CURSOR: hand" alt="" src="http://3.bp.blogspot.com/_hkgyfXKGPaA/R8G8sLPH2oI/AAAAAAAADdQ/MVu18TZlryE/s320/2007gl032314-op01.jpg" border="0" /></a>GRL published an article on estimation of aerosol radiative effects over global land using purely observations from Terra satellite on February 22, 2008. Although, I am one of the co-author in the paper but I would like to congrats Falguni Patadia, first author of the paper for her research, which is first attempt in certain ways. This paper presents the estimation of top of the atmosphere (TOA) short wave aerosol radiative effects over global land areas for each half degree by half degree grid point. The uniqueness of the study comes from the fact that it is purely observation based study, which does not involve any complex radiative transfer and/or climate model runs. Results of the study are encouraging and matches very well with other purely model or hybrid (model and observations) type of studies. This research used one year worth of satellite observations of TOA fluxes derived from CERES broadband instrument, MODIS high resolution cloud masks and MISR derived aerosol optical thickness data sets to perform the analysis. As we all know that, aerosol impacts in climate change studies in one of the most uncertain component and level of scientific understanding about this component is very low. This study is certainly a good start and will help to understand aerosol effects on earth-atmosphere radiation budget. For more details on the results and methodology, please refer the publication and if you do not have access to the article, we will be happy to share reprints with you.<br /><br /><br /><em><strong>Complete Reference:</strong></em><br /></div><br /><div align="justify"><br /><a href="http://www.agu.org/journals/gl/gl0804/2007GL032314/">Patadia, F., P. Gupta, and S. A. Christopher (2008), First observational estimates of global clear sky shortwave aerosol direct radiative effect over land, Geophys. Res. Lett., 35, L04810, doi:10.1029/2007GL032314</a></div>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com3tag:blogger.com,1999:blog-3804224543411119083.post-23500630156698398242008-02-17T22:50:00.003-05:002017-08-27T01:36:50.235-04:00Is atmospheric aerosol an aerosol? comments on the article by Jaenicke<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://1.bp.blogspot.com/_JMOQWjQG5JU/R7j5zfF9Z2I/AAAAAAAADQE/vTbLJr-LgV4/s1600-h/aerosol_cartoon.jpg"><img id="BLOGGER_PHOTO_ID_5168155235322783586" style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer;" alt="" src="https://1.bp.blogspot.com/_JMOQWjQG5JU/R7j5zfF9Z2I/AAAAAAAADQE/vTbLJr-LgV4/s320/aerosol_cartoon.jpg" border="0"></a>The title of a recent article "<a href="http://dx.doi.org/10.1039/b701095h">Is atmospheric aerosol an aerosol?</a>" by Jaenicke caught my attention. This took me back in time, when I was just beginning my career in this field. The first definition I came across or rather assumed was: "anything solid or liquid suspended in the air is aerosol". According to this definition birds and aeroplanes were also aerosols! Thinking of birds and aeroplanes as aerosols wasn't intuitive hence I had to search for a more refined definition. A better one that I came across (well I don't remember from where) was: "any thing suspended in the air and doesn't have self-propelling mechanism is aerosol". This definition implied that mosquitoes are not aerosols but bacteria and virus are. However, this new definition didn't help me win an argument with my friend Neeraj (one of the authors of this blog) who held an opinion that water and ice clouds are aerosols as well, whereas I held the opinion that they are not. We concluded arguments by accepting that clouds are special cases of aerosols and if not explicitly mentioned, atmospheric aerosols mean liquid and solid particles suspended in the air and have aerodynamic diameter between 1e-3 and 1 µm.<br /><br />Technically aerosols are defined as <a href="https://en.wikipedia.org/wiki/Colloid">colloid</a> of air and solid/liquid particles, where air is the dispersion medium and particles are in dispersed phase. The word aerosols brings-in naturally the interaction between particles and air. When particles are not in the air, for example particles collected on filter papers, they are no more aerosols. Hence aerosol is a state of particles rather than the particle itself. This is the reason why most pollution and chemistry related studies report them as particulate matter (PM) because these studies require collecting them on filter papers, while most climate related studies report particles as aerosols since particles are climate modulator as long they are in the air.<br /><br />Coming back to Jaenicke's article, he starts with questioning the very definition of atmospheric aerosol as colloid. Schmauss and Wigand were probably the first to define atmosphere as colloid of air and particles. The word colloid itself was coined in the year 1875 by Gerber to describe a pseudosolution prepared by Selmi (reference in Jaenicke, 2008) . Jaenicke sees a reason to question this definition because colloid implies a stable state, homogeneity and monodispersed size distribution. Hardly any of these is true for atmospheric aerosols. On the other hand there are properties such as surface-to-volume ratio, interactions between nearby particles, multiple scattering, etc that support their definition as colloid. Jaenicke concludes that atmospheric aerosols can be considered colloid in dynamic equilibrium.<br /><br />The crux of the paper is not the discussion on the definition of aerosol but modeling aerosol concentration in the atmosphere under the framework of dynamic equilibrium. Dynamic equilibrium by its nature results in highly variable aerosol concentration. Which in turn requires better temporal resolution for measuring them. In this discussion, Jaenicke highlights quite a few gaps in our knowledge about atmospheric aerosols.<br /><br /><br />References<br /><br />Jaenicke, R. (2008). <a href="http://dx.doi.org/10.1039/b701095h">Is atmospheric aerosol an aerosol?-a look at sources and variability</a>. Faraday Discuss 137, 235-243.<br /><br /><br />Art work: courtesy Malkaush
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Edited to update non-functional links on 27 August 2017.Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com4tag:blogger.com,1999:blog-3804224543411119083.post-32760513632266606602008-02-03T13:49:00.000-05:002008-12-09T16:25:45.773-05:00Satellite remote sensing of active fires: Impact of clouds<div align="justify"><a href="http://1.bp.blogspot.com/_hkgyfXKGPaA/R6YNJOKE7kI/AAAAAAAADQU/3WJP8MzaR24/s1600-h/surface_fire.jpg"><img id="BLOGGER_PHOTO_ID_5162828474897198658" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 343px; CURSOR: hand; HEIGHT: 245px" height="211" alt="" src="http://1.bp.blogspot.com/_hkgyfXKGPaA/R6YNJOKE7kI/AAAAAAAADQU/3WJP8MzaR24/s200/surface_fire.jpg" width="312" border="0" /></a>It has been long time since passive satellite observations in visible and thermal part of the spectrum have been used to monitor and quantify the biomass burning over global areas. Space sensors such as AVHRR, MODIS, and GOES are some of the examples, which continuously monitor vegetation fires under clear sky conditions. But, these sensors are limited to cloud free conditions and there could be large errors in estimation of fire activities due to lack of sampling under cloudy conditions. <a href="http://www.sciencedirect.com/science/journal/00344257">Remote Sensing of Environment</a> published a research article entitled “<a href="http://dx.doi.org/10.1016/j.rse.2007.05.004">Quantifying the impact of cloud obscuration on remote sensing of active fires in the Brazilian Amazon</a>” by Wilfrid Schroeder and coauthors discuss the bias in remote sensing fire data due to possible cloud cover during fire activities over Brazilian Amazon.<br /><br />The abstract read as “Vegetation fires remain as one of the most important processes governing land use and land cover change in tropical areas. The large area extent of fire prone areas associated with human activities makes satellite remote sensing of active fires a valuable tool to help monitor biomass burning in those regions. However, identification of active fire fronts under optically thick clouds is not possible through passive remote sensing, often resulting in omission errors. Previous analyses of fire activity either ignored the cloud obscuration problem or applied corrections based on the assumption that fire occurrence is not impacted by the presence of clouds. In this study we addressed the cloud obscuration problem in the Brazilian Amazon region using a pixel based probabilistic approach, using information on previous fire occurrence, precipitation and land use. We implemented the methodology using data from the geostationary GOES imager, covering the entire diurnal cycle of fire activity and cloud occurrence. Our assessment of the method indicated that the cloud adjustment reproduced the number of potential fires missed within 1.5% and 5% of the true fire counts on annual and monthly bases respectively. Spatially explicit comparison with high resolution burn scar maps in Acre state showed a reduction of omission error (from 58.3% to 43.7%) and only slight increase of commission error (from 6.4% to 8.8%) compared to uncorrected fire counts. A basin-wide analysis of corrected GOES fire counts during 2005 showed a mean cloud adjustment factor of approximately 11%, ranging from negligible adjustment in the central and western part of the Brazilian Amazon to as high as 50% in parts of Roraima, Para and Mato Grosso.”<br /><br /><br />For more details refer the original publication:<br /></div><div align="justify"><br />Wilfrid Schroeder, Ivan Csiszar and Jeffrey Morisette, <a href="http://dx.doi.org/10.1016/j.rse.2007.05.004">Quantifying the impact of cloud obscuration on remote sensing of active fires in the Brazilian Amazon</a>, Remote Sensing of Environment, Volume 112, Issue 2, 15 February 2008, Pages 456-470.</div>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-57803148014981300812008-01-26T13:07:00.000-05:002008-12-09T16:25:46.339-05:00Air pollution in mega cities in China: A Review<div align="justify"><a href="http://4.bp.blogspot.com/_hkgyfXKGPaA/R5t3RuKE6iI/AAAAAAAADFc/5OKa-Oohg5I/s1600-h/china2.jpg"><img id="BLOGGER_PHOTO_ID_5159848944414812706" style="margin: 0px 0px 10px 10px; float: right;" alt="" src="http://4.bp.blogspot.com/_hkgyfXKGPaA/R5t3RuKE6iI/AAAAAAAADFc/5OKa-Oohg5I/s200/china2.jpg" border="0" /></a>Air pollution (both gas and particle) in Chinese mega cities is one of the biggest growing problems due to rapid increase in industrial activities in the area. A review article on air pollution in China entitled “<a href="http://dx.doi.org/10.1016/j.atmosenv.2007.09.003" >Air pollution in mega cities in China</a>” by Chan and Yao is published in January 2008 issue of <a href="http://www.sciencedirect.com/science/journal/13522310">Atmospheric Environment</a>. This article provides through review of available literature on air pollution research in China and focused areas are Beijing, Shanghai, and the Pearl River Delta region. </div><br /><div align="justify">Here, I am providing some highlights of the article. Please refer original article for more details. </div><br /><div align="justify"><a href="http://3.bp.blogspot.com/_hkgyfXKGPaA/R5t3eeKE6jI/AAAAAAAADFk/x_WNWNGCKjA/s1600-h/china1.jpg"><img id="BLOGGER_PHOTO_ID_5159849163458144818" style="margin: 0px 10px 10px 0px; float: left; width: 327px; height: 191px;" alt="" src="http://3.bp.blogspot.com/_hkgyfXKGPaA/R5t3eeKE6jI/AAAAAAAADFk/x_WNWNGCKjA/s200/china1.jpg" border="0" height="170" width="362" /></a>"Air pollution has become one of the top environmental concerns in China. Currently, Beijing, Shanghai, and the Pearl River Delta region including Guangzhou, Shenzhen and Hong Kong, and their immediate vicinities are the most economically vibrant regions in China.”</div><br /><div align="justify">“<a name="bbib66"></a>Air quality in most Chinese cities has improved despite the rapid growth of the economy…, however… He et al. (2001) and <a name="bbib259"></a>Ye et al. (2003) reported that PM2.5 concentrations in Beijing and Shanghai, the two largest cities in China, were about 10 times and six times the WHO guideline values, respectively.”</div><br /><div align="justify">“From 1980 to 2005, the urban population in China increased from 19.6 to 40.5%. The number of cities increased to over 660, and more than 170 cities had over 1 million permanent residents (not including the migrant population) in 2004.”</div><div align="justify"><br />“Much attention has been paid to reducing emissions, particularly vehicle emissions. Although the number of vehicles has increased by about 10% per year in these cities, NO2 and CO concentrations have not increased due to effective control measures… Particulate pollution is still severe, and it is the major air pollution problem in the mega cities.”</div><br /><br /><div align="justify"><strong><em>Complete Reference:</em></strong> </div><br /><div align="justify"></div><div align="justify"><a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VH3-4PNFVCJ-3&_user=10&_coverDate=01%2F31%2F2008&_rdoc=2&_fmt=summary&_orig=browse&_srch=doc-info%28%23toc%236055%232008%23999579998%23677368%23FLA%23display%23Volume%29&_cdi=6055&_sort=d&_docanchor=&_"><em></em></a><a name="bcor1"></a>Chan, C. K. and X. Yao (2008, January), <a href="http://dx.doi.org/10.1016/j.atmosenv.2007.09.003">Air pollution in mega cities in china</a>, <em>Atmospheric Environment </em> <em>42 </em>(1), 1-42, doi:<a href="http://dx.doi.org/10.1016/j.atmosenv.2007.09.003" target="doilink" onclick="var doiWin; doiWin=window.open('http://dx.doi.org/10.1016/j.atmosenv.2007.09.003','doilink','scrollbars=yes,resizable=yes,directories=yes,toolbar=yes,menubar=yes,status=yes'); doiWin.focus()">10.1016/j.atmosenv.2007.09.003</a> <em></em><em></em><br /></div>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com4tag:blogger.com,1999:blog-3804224543411119083.post-82673946940980240792008-01-08T15:57:00.002-05:002009-05-21T03:26:01.555-04:00One Year of Aerosol Blog (about us)<div align="justify"><strong><em>Hello all Readers,<br /></em></strong><br />Today, aerosol blog completed successful one year. So we thought to write a blog about our blog. The blog was started last year in first week of January. Initially there were only two authors (Harish and Pawan) but soon Falguni, Neeraj and Dilip joined team, making it possible to post 42 posts in one year, almost one post per week. Here we take a look on what make us to start this blog, what content is dear to us and what is the future of this blog.</div><br /><strong><em>"Hey listen to this!"</em></strong><br /><br /><div align="justify">It is common tendency of human being when we see something interesting we want to share it with others. Who is not aware of such a friendly shout "hey listen to this" with family members at home, with friends in hostel, when someone found interesting paragraph in news-paper or book. We five members of current team once upon a time where in Physical Research Laboratory and use to enjoy such a sharing. Later on we moved to different places but still use to shout through e-mail "Hey see this is interesting". Every year more than 7500 peer reviewed articles are published in the field of atmospheric science, quite a big fraction of it are published in the field quite close to our research work. We realized that it would be very useful if there would have been a guide to help short-list relevant articles. With these two intention we started blog, later on we realized that blog is quite promising medium for publication and can work as e-magazine.<br /><br /></div><div align="justify"></div><div align="justify"><strong><em>Objectives<br /><br /></em></strong></div><div align="justify"></div><div align="justify">Our current objective is to provide pointer to information relevant to the research in the field of aerosols, clouds and climate change, be it journal article, book, web-site, biography, patent, database, conference or job. It is also part of objective to provide perspective why that piece of information is interesting. However as far as possible we want to focus on technical aspects of the research in this field rather than popular aspects. In future we want to transform our blog in e-magazine with its own articles, commentaries, digest and announcements.</div><div align="justify"><br /><strong><em>Is this blog free?<br /><br /></em></strong></div><div align="justify">This blog is free for viewing, but free is very deceptive word. We believe truly free viewing should be free of advertisements. What is the point in shortlisting articles if again one has to search them through jungle of ad links. We are able to provide it free because we are using resources available free of charge. As stated in earlier paragraph that we intend to make our blog an e-magazine. This may require some kind of investment such as server, software, domain name etc. But it will be our highest priority to run this blog free of charge and free of advertisement.</div><div align="justify"><br /><em><strong>Who are the authors?<br /><br /></strong></em></div><div align="justify">We are currently five authors who are responsible to update blog on regular basis. We have established credentials in this field and have articles published in peer reviewed journals. More information about authors can be found at their home-page listed below</div><div align="justify"><br /><strong>Harish Gadhavi</strong>- <a href="http://www.atmos.umd.edu/%7Eharish/">http://www.atmos.umd.edu/~harish/</a><br />Post doctoral research fellow at University of Maryland, College Park<br /><strong><br />Pawan Gupta</strong> - <a href="http://www.nsstc.uah.edu/%7Egupta/">http://www.nsstc.uah.edu/~gupta/</a><br />Graduate student at University of Alabama, Huntsville<br /><strong><br />Neeraj Rastogi</strong> - <a href="http://www.prl.res.in/%7Enrastogi">http://www.prl.res.in/~nrastogi</a><br />Post doctoral research fellow at University of Georgia, Atlanta<br /><strong><br />Falguni Gupta</strong> - <a href="http://www.nsstc.uah.edu/%7Efalguni/">http://www.nsstc.uah.edu/~falguni/</a><br />Graduate student at Universtiy of Alabama, Huntsville<br /><strong><br />Dilip Ganguly</strong> - <a href="http://www.prl.res.in/%7Edganguly/">http://www.prl.res.in/~dganguly/</a><br />Post doctoral research fellow at Princeton University, Princeton, NJ</div><div align="justify"><br />We welcome contributions from anyone who wants to contribute or share a piece of information consistent with the theme of blog. Announcement regarding conferences, job are most welcome. Contact information can be found in the end of the blog<br /><br /></div><div align="justify"><strong><em></em></strong></div><div align="justify"><strong><em>Copyright<br /><br /></em></strong></div><div align="justify"></div><div align="justify">We have unspecified status of copyright for our blog. Authors own the copyright individually as allows the law. If not specifically mentioned about restriction, feel free to use our blog for non-commercial purpose. We sometime use figures and texts from others as fair use policy allows, but copyright to those figures and texts belongs to originating source. We try our best to cite full reference for such a source. If we have adversely used copyrighted material, please bring to our notice and we will immediately remove it. Contact information can be found in the end of the blog<br /><br />Please see the home-pages of authors to contact authors individually.<br /><br /></div><div align="justify"> </div><div align="center"><em>Thanks to Harish for preparing these notes!</em></div><div align="justify"> </div>Pawan Guptahttp://www.blogger.com/profile/12158614556266774133noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-46701794084193431992007-12-08T15:19:00.001-05:002008-12-09T16:25:46.513-05:00The Story of StuffCouple of days back, a professor in my department forwarded me the link of this movie, saying it is 20 min long but worth seeing. After seeing I realized that this was the best animation I have ever seen. <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://www.storyofstuff.com/index.html"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="http://3.bp.blogspot.com/_JMOQWjQG5JU/R1r9Ph6cbzI/AAAAAAAADBs/ZXBK-cQXw0w/s320/story_of_stuff.gif" alt="" id="BLOGGER_PHOTO_ID_5141700367840210738" border="0" /></a><br /><br />Click on the image or <a href="http://www.storyofstuff.com/index.html">here</a> to see movie. I don't want to spoil surprise by writing more about movie but if you trust my words, you are guaranteed your time will not be wasted.Anonymoushttp://www.blogger.com/profile/12192850965291414389noreply@blogger.com0tag:blogger.com,1999:blog-3804224543411119083.post-69006975479578684262007-11-29T18:40:00.000-05:002008-02-24T14:00:17.494-05:00Inter-relationship between the chemistry of aerosols and precipitation and their implicationsThe large-scale anthropogenic emissions have been increasingly affecting the air quality as well as regional and global climate by altering Earth’s surface temperature and precipitation patterns. These pollutants are removed from the atmosphere via wet and dry deposition, which in turn may adversely affect the terrestrial and aquatic environments, ranging from acidification of soils and inland waters to the damage of buildings and monuments. The regional precipitation chemistry provides the simplest way to assess the influence of human activities on the composition of the atmosphere, and to improve knowledge of physico-chemical processes related to the atmospheric transport and deposition of pollutants. The chemical composition of an individual precipitation event is dictated by ‘in-cloud’ and ‘below-cloud’ scavenging of atmospheric aerosols and gaseous species derived from natural and anthropogenic sources. Wet and dry deposition also provides information on the exchange of chemical components between the atmosphere and the land/ocean and hence it is an important link in understanding the biogeochemical cycles of important chemical elements such as N, P and S.<br /><br />Rastogi and Sarin (2007) have discussed the inter-relationship between aerosol and rain composition collected over a period of three years at Ahmedabad, an urban city located in a semi-arid region of India. They have proposed a simple way (comparison of ionic ratios in aerosol and rain) to understand the dominant scavenging processes (in-cloud/below-cloud) of chemical species and the phase (gaseous vis-à-vis particulate) from which it is scavenged by rain. By first direct measurement of alkalinity in rainwater over India, they have discussed the reason of alkaline rain over their study region, in spite of high concentrations of acidic pollutants like SO4 and NO3.<br /><br />For more details, please read the following article and references therein:<br /><br />Rastogi, N. and Sarin, M.M., 2007. Chemistry of precipitation events and inter-relationship with ambient aerosols over a semi-arid region in western India. Journal of Atmospheric Chemistry 56, 149-163. (DOI 10.1007/s10874-006-9047-5).Neeraj Rastogihttp://www.blogger.com/profile/11045795252046319492noreply@blogger.com0