Air Pollution, Aerosols and Clouds in the Climate System

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...