Air Pollution, Aerosols and Clouds in the Climate System

Recently, I came across this nice article published in JGR, which talks about impact of using biofuels on regional climate in the United States . The debate on using biofuels for future energy needs is on. Abstract reads as “ 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 United States . In the absence of strain/crop-specific parameterizations, a primary goal of this work was to isolate the maximum regional cl...

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 India . Original data for the image is taken from NASA’s MODIS Rapid Fire System and processed at University of Alabama in Huntsville , AL . For more news on fire http://news.bbc.co.uk/2/hi/south_asia/8333211.stm

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. http://www.agu.org/meetings/fm09/program/scientific_session_search.php?show=detail&sessid=645 Abstract submission is open now and last date is September 3, 2009. 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. Following link provides guidelines to submit the abstract. http://www.agu.org/meetings/fm09/index.php#software Thanks and hope to see your abstract soon in AGU system.

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 thic...

The title of a recent article " Is atmospheric aerosol an aerosol? " 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 n...

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. Remote Sensing of Environment published a research article entitled “ Quantifying the impact of cloud obscuration on remote sensing of active fires in the Brazilian Amazon ” by Wilfrid Schroeder and coauthors discuss the bias in remote sensing fire data due to possible cloud cover during fire activities over Brazilian Amazon. 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 pr...

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 “ Air pollution in mega cities in China ” by Chan and Yao is published in January 2008 issue of Atmospheric Environment . 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. Here, I am providing some highlights of the article. Please refer original article for more details. "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.” “ Air quality in most Chinese cities has improved despite the rapid growth of the economy…, however… He et al. (2001) and Y...

Hello all Readers, 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. "Hey listen to this!" 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 ...

Couple 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. Click on the image or here 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.

The 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 c...

In most climate and radiative transfer models, optical properties of aerosols are modeled using spherical shape assumptions. This assumption is based on sound scientific reasoning. All liquid aerosols have spherical shape because of surface tension. Solid aerosols, which are water soluble also eventually absorbs water vapor from atmosphere and transform themselves into spherical shape. However, dust aerosols are neither liquid nor water soluble. Soot aerosols also fall in this category. Hence, they may not necessarily have spherical shape. This requires that we should examine the validity of spherical shape assumption, particularly for these two types of aerosols. There are two aspects to look at for importance of spherical shape assumption. One is relative magnitude of non-spherical aerosol number concentration. If there are not quite large number of non-spherical particles in the atmosphere, then we need not worry about it. Li and Osada (2007) have shown using model study that dust ...

Recently I received quite a good number of conference related notifications. Many of reader of this blog may be participating it and they shouldn't miss the dead-line so I am listing them below. If you know conference that is not listed below but related to theme of this blog please let us know. 15th National Space Science Symposium, India (NSSS-2008) National Space Science Symposium is one the largest gathering of space scientist in India. It covers wide variety of subjects including remote sensing of atmosphere and climate change study. The next NSSS is going to be held at Radio Astronomy Centre (NCRA-TIFR) in Ooty between 26 and 29 February 2008. Ooty is one of the famous hill-station in India. Last date to submit abstract Dec 7, 2007. Broad subject areas covered in this conference Space- and ground-based astronomy and astrophysics, planetary science / exploration Solar radiation and its interaction with earth's near and distant environment Magnetosphere, ionosphere, therm...

Indoor or outdoor air may contain thousands or even millions of microorganisms and biological particles in just one cubic meter of air. These airborne particles are collectively referred to as bioaerosols. Examples of bioaerosols include viruses, bacteria, fungi, pollen, fragmented particles from microbial cells or insects, and by-products of living organisms (e.g. animal dander, insect excrement). The size of these particles generally varies between a fraction of a micrometer (µm) to approximately 30 µm. Bioaerosols may originate from numerous natural or man-made sources such as agriculture (harvesting, storage, composting etc) and industrial activities (manufacturing, food processing etc), indoor surfaces (ceiling, wall, carpets, house plants) and water treatment plants etc. Particle size is an important factor in determining risks associated with microbial contamination. In general, particles > 20 µm (fungi, algae, pollen etc) affect Region 1, Particles Modern airborne sampling o...

Annual fall meeting of American Geophysical Union (AGU) and annual meeting of American Meteorological Society (AMS) is approaching close in December 2007 and January 2008 respectively. These are two biggest events in USA where more than 20 thousands scientist from around the world get together to discuss, show and present their research in various areas of Earth Sciences. Environment science is one of the main focus area in both meetings and several thousands research studies on the same will be presented. The next AMS (88th Annual Meeting) will be held in, New Orleans, LA, USA during 20-24 January 2008. Please click on the link to see various topics covered by AMS-2008 http://www.ametsoc.org/meet/annual/programsandevents.html and This year AGU Fall meeting will be held in San Francisco, CA, USA during 10–14 December 2007. For more details click here http://www.agu.org/meetings/fm07/

The Norwegian Nobel Committee has decided that the Nobel Peace Prize for 2007 is to be shared, in two equal parts, between the Intergovernmental Panel on Climate Change (IPCC) and Albert Arnold (Al) Gore Jr. for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change. Indications of changes in the earth’s future climate must be treated with the utmost seriousness, and with the precautionary principle uppermost in our minds. Extensive climate changes may alter and threaten the living conditions of much of mankind. They may induce large-scale migration and lead to greater competition for the earth’s resources. Such changes will place particularly heavy burdens on the world’s most vulnerable countries. There may be increased danger of violent conflicts and wars, within and between states. Through the scientific reports it has issued over the past two decades, the IPC...

The Inter-governmental Panel on Climate Change reviews the best available scientific information on climate change and publishes a report every 5-6 years. The fourth assesment report was released this year and is the IPCC 2007 report. In contrast to the IPCC 2001 report, this report emphasizes with greater confidence that global warming is due to human/anthropogenic activities. Until recently, the sign of the anthropogenic radiative forcing was uncertain largely due to the uncertainty associated with radiative effects (direct and indirect) of atmospheric aerosols. Haywood and Schulz in their recent paper (titled above) inter-compare the probability distribution function of anthropogenic radiative forcing from IPCC 2001 and IPCC 2007 and show that a significant progress has been made in reducing the uncertainty in anthropogenic radiative forcing since IPCC 2001. They conclude that " the single most contributor to this conclusion appears to be the reduction in the uncertainty associ...

The United Nations (UN) office for outer space affairs , the government of Austria and the European Space Agency (ESA) jointly organized a symposia on “ space tools and solution for monitoring the atmosphere in support of sustainable development ”. The United Nations invites participants from several nations to attend the symposium every year. There were more than 70 scientists representing more than 41 countries who gathered in Graz , Austria during September 11-14 to discuss various available space tools for monitoring the atmosphere in support of sustainable development. This year’s symposium included a hands-on tutorial and interactive training session on “ Satellite Tools and Applications for Air Quality ”. I was part of the team, which developed material and conducted the training session. I would really like to take this opportunity to thank my supervisor Dr. Sundar Christopher for providing me this wonderful opportunity and NASA’s applied science program manager Lawrence Fried...

The first time my interest in aerosol science picked up was when I learnt about nuclear winter -- a phenomena which refers to possible climatic impact of all-out nuclear war. What really fascinated me was the idea that if one wants to control climate or weather in predictive manner, aerosols are going to be the best tool; for a reason that they have relatively short life-time giving control over their introduction and removal in the atmosphere. Well! this is not the subject of today's post. Thinking of my own interests in this field led me to think about history of aerosol science. Couple of years before I read Spencer Weart's " The Discovery of Global Warming ". I am fascinated by its content and writing style. Experience was not less than reading suspense thriller. Later on, I come across a comment that book is weighted toward contributions of American scientists than European scientists. I do not know the truth as my knowledge in the history of climate science is l...

It is widely know that dust is essentially non-spherical and hence radiative transfer calculations treating dust as a spherical particle are not adequate. A recent laboratory based study on dust particles by Jingmin Li and Kazuo Osada is very interesting. This article appeared in GRL this month. They study the preferential setting of elongated mineral dust collected from snow in a high mountain in Japan. The positions of particles' centers of gravity and folding centers are analyzed using a scanning electron microscopy and optical microscopy. Their results suggest that a preferential orientation exists for particles settling heavy side down (as expected) but what is interesting is the analysis of results from Ginoux's model wherein they apply this preferential orientation information and show that : " away from the source regions, dust particles are essentially spherical, which considerably simplify the calculation of settling velocity in transport and of radiative trans...

Aerosols are thought to have a cooling effect on the atmosphere, and therefore to have mitigated some of the expected global warming over this period. This is, however, a highly uncertain conclusion, in part because the total amount and vertical distribution of solar radiation that is absorbed by aerosol particles is imperfectly known. There was an interesting article in Nature (Vol-448, 2 August 2007) under “News and Views” by Prof. Peter Pilewskie . In the same issue, Ramanathan et al . (on page 575) report that the aerosol clouds above large regions of Asia actually cause as much warming as greenhouse gases — in contradiction, at first glance, to the notion of aerosol particles as a cooling agent. Figure 1. Smog drifts down India's populous Ganges valley and out into the Bay of Bengal. This is the source of 'atmospheric brown clouds' over the Indian Ocean, and the climatic effect of its constituent aerosol particles is investigated by Ramanathan and colleagues For more i...