Multiple Technologies Estimate Aerosol Effect on Surface and Atmosphere Radiation Budget

Tropospheric aerosols are believed to play an important role in modulating the Earth's energy budget. Direct aerosol effects include the scattering and absorption of solar radiation: there is less (but still significant) scattering, absorption, and emission in the thermal infrared. In part, because aerosols vary widely in space, time, and composition, their radiative forcings have not been quantified with accuracy sufficient to allow a much- needed assessment of the effect of aerosols on global climate. Recent advances in space-based sensor capabilities (Visible Imaging spectRometer Suite (VIRS) and the Moderate Resolution Imaging Spectrometer (MODIS)) for retrieving aerosols and also improved aerosol transport and chemistry modeling capabilities (Model of Atmospheric Transport and Chemistry (MATCH)) have provided unprecedented information on aerosols. NASA's Cloud's and the Earth's Radiant Energy System project (CERES) has benefited from teaming with research groups performing space based aerosol retrievals and advanced aerosol chemistry and dispersion modeling. By coupling measurements of the aerosol forcing from space with specialized observations at the surface, top and bottom closure for aerosol forcing to the atmospheric column can be achieved. We present a recent history of CERES' progress in quantifying the aerosol forcing component of the energy budget by integrating satellite sensor observations with radiative transfer modeling. Data from surface observation sites and from CERES/Surface and Atmosphere Radiation Budget (SARB) edition 2A retrievals from the TERRA platform for the years 2000 and 2001 are presented. In these data, an error bias (satellite derived - surface measured) of surface downward diffuse shortwave irradiance shows a functional relationship with aerosol forcing. These results indicate additional progress in understanding the global aerosol's temporal, spatial, and compositional nature is needed to reduce the present uncertainty of direct aerosol forcing on the climate system. Progress in improved aerosol quantities by MODIS retrievals over an ocean observation site developed by CERES is demonstrated. I. Introduction ccounting for the radiative effects of aerosols within the atmosphere is required to give future global climate models more accurate predictive capabilities. Aerosols and clouds are similar because both are extremely small particulates in the atmosphere. They may be treated identically by radiative transfer models if the full detail of their locations within the atmosphere and their complete optical properties are known. These aerosols and clouds modulate the incoming and outgoing radiation of the planet in the shortwave and the longwave regimes. The suspended particles within the atmosphere interact with both the shortwave and longwave radiation in a size (of the aerosols) and wavelength (of the intervening radiation) dependent manner. The resulting primary and secondary scattering and absorption of the radiation increases the complexity of characterizing these radiative effects. NASA's CERES program was established to collect a multi-year dataset that could be used to develop methods that can A