HR: 09:40h
AN: A41E-07 INVITED     [Abstracts]
TI: Natural and Anthropogenic Aerosols in the World's Megacities and Climate Impacts
AU: * Kafatos, M
EM: mkafatos@gmu.edu
AF: Center for Earth Observing and Space Research, 4400 University Dr MSN 5C3, Fairfax, VA 22030 United States
AU: Singh, R
EM: rsingh3@gmu.edu
AF: Department of Civil Engineering, Indian Institute of Technology, Kanpur, 208 016 India
AU: El-Askary, H
EM: helaskar@gmu.edu
AF: Center for Earth Observing and Space Research, 4400 University Dr MSN 5C3, Fairfax, VA 22030 United States
AU: El-Askary, H
EM: helaskar@gmu.edu
AF: Department of Environmental Studies, Faculty of Science Alexandria University, Alexandria, 22030 Egypt
AU: Qu, J
EM: jqu@gmu.edu
AF: Center for Earth Observing and Space Research, 4400 University Dr MSN 5C3, Fairfax, VA 22030 United States
AU: Qu, J
EM: jqu@gmu.edu
AF: NASA, Goddard Space Flight Center, Greenbelt, MD 20771 United States
AB: The world's megacities are the sites of production of a variety of aerosols and are themselves affected by natural and human-induced aerosols. In particular, sources of aerosols impacting cities include: industrial and automobile emission; sand and dust storms from, e.g., the Sahara and Gobi Deserts; as well as fire-induced aerosols. Improving the ability of various stakeholder organizations to respond effectively to high concentrations of aerosols, with special emphasis on mineral dust from dust storms; smoke from controlled burns, wild fires and agricultural burning; and anthropogenic aerosols, would be an important goal not just to understand climate forcings but also to be able to better respond to the increasing amounts of aerosols at global and regional levels. Cities and surrounding areas are affected without good estimates of the current and future conditions of the aerosols and their impact on regional and global climate. Remotely sensed (RS) NASA, NOAA and international platform data can be used to characterize the properties of aerosol clouds and special hazard events such as sand and dust storms (SDS). Aerosol analysis and prediction-model capabilities from which stakeholders can choose the tools that best match their needs and technological expertise are important. Scientists validating mesoscale and aerosol-transport models, aerosol retrievals from satellite measurements are indispensable for robust climate predictions. Here we give two examples of generic SDS cases and urban pollution and their possible impact on climate: The Sahara desert is a major source of dust aerosols dust transport is an important climatic process. The aerosols in the form of dust particles reflect the incoming solar radiation to space, thereby reducing the amount of radiation available to the ground, known as `direct' radiative forcing of aerosols. The aerosols also change the cloud albedo and microphysical properties of clouds, known as `indirect' radiative forcing of aerosols. The highest boundary layer heights are associated with regions where the sensible heat flux is greatest, and latent heat flux is smallest due to lack of vegetation. Boundary layer heights in the deserts may be systematically higher than the slightly wetter regions at the edges of deserts. Latent heat flux model runs and MODIS observations of dust storms affecting the Nile Delta and Cairo indicate strong influence on the local weather and climate forcings. In the Indo-Gangetic, during the pre-monsoon period, dust storms form. We have examined SDS transport using RS data acquired from NASA's MODIS MISR instruments and from sun photometer measurements. The aerosol optical depth and size of the dust particles are found to be significantly higher during such dust storm events. Moreover, our results clearly show that power plants in this region are the key point source of air pollutants. The detailed analysis of aerosol parameters show the existence of absorbing and non-absorbing aerosols emitted from these plants. The combined effects of urban aerosols with dust aerosols in India and Cairo not only affect megacities, they also have long-term climate impacts. We will also discuss how the assimilation of RS data into mesoscale models can improve these models and predictability of hazards and effects on megacities, such as SDS events, and forest fires, all sources of aerosols. Therefore RS data can improve the prediction of climate forcings by aerosols.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005