Atmospheric aerosols affect climate and climate change directly, by scattering and absorbing shortwave (solar) radiation, and indirectly, by modifying the microphysical properties of clouds, influencing cloud reflectivity, precipitation development, and the like. The radiative forcing of climate change by anthropogenic aerosols--that is, changes in components of Earth's radiation budget--is recognized to be substantial in the context of other forcings of climate change over the industrial period, principally longwave forcing by incremental greenhouse gases. However the aerosol forcing is much more uncertain, and this uncertainty is the greatest source of uncertainty in radiative forcing of climate change over the industrial period. Key sources of uncertainty in aerosol forcing are uncertainties in changes in the amount (mass loading), geographical distribution, chemical composition, and microphysical structure of atmospheric aerosols resulting from anthropogenic emissions of aerosols and aerosol precursors affecting aerosol radiative and cloud-nucleating effects. In recognition of this situation the Department of Energy (DOE) Atmospheric Science Program (ASP) is focusing on the chemical and microphysical processes of atmospheric aerosols governing their radiative forcing of climate change. This Program consists of some 32 Science Projects together with supporting infrastructure activities. Principal components of the Program are field studies, instrument development, laboratory studies and theory, and modeling. Projects comprising the Program are selected competitively in response to solicitations announced from time to time by DOE. Principal program deliverables will consist of models and parameterizations suitable for representing aerosol properties and processes required to compute aerosol radiative forcing of climate in large-scale climate models, together with supporting science deliverables--data sets and other accounts of research. A major field study examining aerosol-cloud interactions was just conducted along the mid-California Coast in conjunction with the DOE Atmospheric Radiation Measurement (ARM) mobile facility and the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) at the Naval Postgraduate School together with researchers from the California Institute of Technology. The next major ASP field project will take place in and around Mexico City in March, 2006, as part of a larger collaborative international study, the Megacity Initiative: Local and Global Research Observations (MILAGRO) to be conducted in collaboration with a National Science Foundation study, Megacity Impacts on Regional and Global Environments--Mexico City (MIRAGE-Mex); with research supported by the National Aeronautics and Space Administration; and with Mexico City Metropolitan Area atmospheric studies funded primarily by Mexican agencies. All of these studies are aimed at improving understanding of aerosol chemistry, physics, and impacts. For further information about ASP please visit the ASP web page, http://www.asp.bnl.gov.
This page was last updated 2005-09-19.
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