Air Pollution, Aerosols and Clouds in the Climate System

From my graduate school experience I find that the best way to learn and understand science is by getting your hands dirty with the relavant data when it comes to understanding remote sensing. Like remote sensing courses at many other universities in the United States, the University of Alabama in Huntsville offers two courses in Satellite Remote Sensing, ATS670 and ATS770 . These courses are tailored in a manner to that allows students to get hands on experience with state-of-the art remote sensing datasets such as the MODIS . In ATS670, students select a MODIS image of their interest and perform a supervised and unsupervisd classification of the image to identify different features in the image such as land, water, clouds, aerosols, vegetation etc. The beauty of doing all this is that the student doesn't get to use any classification software! They write their own routines to perform all the required tasks including trivial tasks such as calculating minimum, maximum, mean, stand...

Atmospheric aerosols in general and biomass burning aerosols in particular have recently attracted extensive interest owing to their ability to affect the climate on local to global scales. These climatic effects include a direct radiative effect due to the aerosols’ ability to scatter and absorb incoming sunlight, an indirect effect due to the aerosols’ ability to serve as cloud condensation nuclei (CCN), increasing the cloud’s reflectivity and lifetime, a semidirect effect which leads to reduction in cloud cover, owing to aerosols’ ability to absorb sunlight, changes in precipitation patterns, and export of pollutants and water vapor to the stratosphere. Therefore, it is important to assess human contribution to aerosol emissions, and to assign a source to both anthropogenic and natural aerosols, for understanding the respective contribution of different aerosol types to climate change. Levoglucosan (1,6-anhydro-β-D-glucopyranose) is a unique tracer for biomass burning sources in atm...

Ultraviolet (UV) radiation plays very important role in bio-geo-chemical cycle. Their harmful effects include skin cancer, cataract, immune suppression, reduction in crop yield, etc. Beneficial effects are synthesis of vitamin D in human body, treatment of psoriasis, etc ( Lucas et al., 2006 ). My interest in UV radiation is how it interacts with atmospheric aerosols. Aerosols are one of the many factors which determines amount of surface reaching UV radiation. While scattering type of aerosols may reduce surface reaching UV radiation, they increase the actinic flux which in turn increases the photolysis rate for smog formation ( Dickerson et al., 1997 ). Relation of aerosol and UV radiation is not one-way; while aerosols affect surface reaching UV radiation, they are affected by surface reaching UV radiation. This is particularly true for naturally produced sulfate aerosol. Recently scientific community has shown a lot of interest to study UV induced sulfate aerosol production to bet...

"All models have assumed that particles are spherical and have chosen single values for the refractive index. If underlying model assumptions are inappropriate, then scattering, absorption and radiative forcing estimates will be incorrect." This is one the statement made by Tami Bond and Robert Bergstrom in the review paper titled ‘Light Absorption by Carbonaceous Particles: An Investigative Review’ published in Aerosol Science and Technology, 2006. I had chance to present this paper as class seminar in my ‘Atmos pheric Aerosol’ class teaching by Dr. Kirk Fuller during this summer. Let me tell you this, “this is one of the best written paper I ever read on carbon aerosols”. It reads very well and has almost all the information you need to know about atmospheric carbon aerosols and their optical properties. Personally, I congratulate and thanks Tami and Robert for putting together this wonderful paper. Below, I will briefly touch some important points from the paper. Motivati...

Its time for aerosol scientists to gear up for the upcoming Glory Mission that has a fantastic passive sensor for monitoring aerosols from space with unmatched retrieval accuracies of 0.02 over ocean and 0.04 over land! This article on the Glory Mission appeared in BAMS in the May 2007 edition, volume 88, number 5. It has a very detailed description of the science objectives, the instruments on Glory, measurement objectives, the data products from these instruments, associated uncertainties and validation plans. Glory is basically a part of the A-Train constellation of satellites. It is scheduled to be launched in 2008 and will carry two independent instruments : 1) The Total Irradiance Monitor (TIM) 2) The Aerosol Polarimetry Sensor (APS) The main purpose of the Glory mission is to help address the challenge of reducing uncertainty in adequately contraining climate sensitivity. Glory is intented to specifically meet the following four scientific objectives : " • improve the quant...