Extended Abstract (560K)4.4
Analysis of Solar Absorption Derived from ARM Surface and Satellite Measurements
Anita D. Rapp, AS&M, Inc., Hampton, VA; and D. R. Doelling, M. M. Khaiyer, P. Minnis, W. L. Smith, and L. Nguyen
The second Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE II) was designed to provide insight on the debate of whether or not cloudy skies enhance solar absorption. The experiment brought together surface, aircraft, and satellite measurements. The CERES instrument provides the only directly measured top of atmosphere (TOA) broadband shortwave albedos for the ARM SGP site. Because the CERES instrument does not provide continuous diurnal sampling of the SGP central facility, other datasets must be employed. GOES-8 visible radiances are converted to CERES-like broadband shortwave fluxes using conversion derived from correlations of GOES-8 narrowband and coincident CERES broadband measurements. These broadband fluxes are then validated against aircraft fluxes. ARESE-II only covered the cloud conditions for a single month over the SGP site. To provide a more comprehensive assessment of solar radiation absorption in clouds over this area, this paper uses the GOES-8 CERES-like TOA broadband radiative fluxes, the ARM surface fluxes, and cloud properties derived from GOES-8 to derive shortwave cloud radiative forcing (CRF) at the surface and the top of the atmosphere (TOA) for a full year of GOES-8 data. Absorption parameters following the methods of Cess et. al (1995) are calculated using the collocated and coincident surface and satellite measurements. Fu-Liou model calculations of absorption during the ARESE II IOP are compared with empirical estimates using the observed cloud proeprties. Preliminary results do not indicate the presence of enhanced shortwave radiation absorption in cloudy skies. The seasonal variations of each of these parameters will be presented.
Session 4, Shortwave Absorption in Clouds: Measurements and Modeling
Wednesday, 5 June 2002, 10:30 AM-12:00 PM
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