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The Solar Radiative Energy Budget in the Arctic |
NASA Ames Research Center, Moffett Field, California
Bay Area Environmental Research Institute, San Francisco, CA
University of Washington, Seattle, Washington
University of Washington, Seattle, Washington
University of California at Santa Barbara, Santa Barbara, CA
During the FIRE (First ISCPP Regional Experiment) Arctic Cloud Experiment and coincident SHEBA (Surface Heat Budget of the Arctic Ocean) campaign, detailed moderate resolution solar spectral measurements were made to study the radiative energy budget of the coupled Arctic Ocean - Atmosphere system. We acquired solar spectral irradiance throughout the atmospheric column using the NASA Ames Solar Spectral Flux Radiometer (SSFR). Identical instruments were deployed on the NASA ER-2, from May 18 to June 7; the University of Washington CV-580, from May 19 to June 24; and at the SHEBA ice camp near the Canadian Coast Guard Ship, Des Groseilliers, from May 14 to June 24. On both aircraft the SSFR viewed in both the zenith and nadir directions, measuring moderate resolution (5-15 nm) spectral irradiance continuously between 300-2200 nm. On the ice surface at the SHEBA ship the SSFR was zenith pointing.
These data are being used to examine the spectral, temporal, and spatial (horizontal and vertical) distribution of solar flux over the radiatively complex Arctic region. Our preliminary analysis shows a high level of agreement between measured and modeled flux at 20 km, but the bias is greater at the surface. We have found that the ice surface and overlying stratus can be discriminated easily using near-infrared spectra reflectance at wavelengths greater than 700 nm. A general characterization of solar radiative energy deposition reveals that thin clouds tend to reduce the absorbed near infrared radiation by the surface-atmosphere system while the trend for thick clouds is to enhance solar absorption.
