Wednesday, 5 June 2002: 11:15 AM
Analysis of Solar Absorption Derived from ARM Surface and Satellite Measurements
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.
Supplementary URL: