This page's content is no longer actively maintained, but the material has been kept on-line for historical purposes.
The page may contain broken links or outdated information, and parts may not function in current web browsers.

GACP Projects

Determination of the Direct Radiative Forcing by Smoke Aerosols over Boreal Forests and by All Aerosols over Global Oceans

Zhanqing Li, PI
Jeff Wong, Co-I

Abstract: Direct radiative forcing (DRF) by aerosol is an important measure of the direct impact of aerosols on the Earth's climate. It is defined as the difference in the radiative energy under clear-sky conditions with and without the presence of aerosols. Due to the meager observations of aerosol properties, there exists a large gap among the current estimates of DRF which hinders our ability of modeling the climate and its changes. In response to the NASA's solicitation for studies on "developing an understanding of aerosol radiative forcing of climate", we propose to derive climatologies of the DRF due to smoke aerosols over the boreal forest and due to all aerosols over global oceans from satellite and surface measurements and model calculations.

The proposed study is expected to have some unique contributions to the development of an aerosol DRF climatology. First, the approach of our study is different from the existing one. Instead of relying on the retrieved aerosol optical properties (optical thickness, single scattering albedo, phase functions) to compute DRF, we will determine DRF directly from satellite and surface measurements together with model results of aerosol-free radiative transfer calculations. This can circumvent difficulties and uncertainties suffered from the retrieval of aerosol properties. Second, it will fill or narrow the knowledge gap in understanding the impact of smoke aerosols from biomass burning in the boreal biome. Many studies on biomass burning have been carried out in the tropics but little has been done in the large areas of boreal forests. Third, the climatology of DRF that we develop over the global oceans provides an independent product for intercomparison with those derived from a traditional approach, which helps define the uncertainties in the DRF climatology. Fourth, this study will make combined use of a wide variety of satellite (AVHRR/ERBE/ScaRaB, CERES/MODIS, SSM-I, NSCAT, CZCS or SeaWiFS, etc.) and surface (pyranometer, pyrheliometer, sunphotometer, etc.) measurements, and model results.

Back to Individual Projects page