Portal de Periódicos da CAPES

Derivation and Applications of Near-Infrared Cloud Reflectances from GOES-8 and GOES-9

1998; American Meteorological Society; Volume: 37; Issue: 8 Linguagem: Inglês

10.1175/1520-0450(1998)037 2.0.co;2

1520-0450

J. Turk, J. Vivekanandan, T. Lee, P. A. Durkee, K. Nielsen,

Atmospheric and Environmental Gas Dynamics

Recent deployments of the National Oceanic and Atmospheric Administration (NOAA) Geostationary Operational Environmental Satellites (GOES-8 and -9) include full-time 3.9-μm imaging capabilities. This shortwave (near infrared) channel has been available at 3.7 μm on the Advanced Very High Resolution Radiometer (AVHRR) instrument aboard the NOAA polar-orbiting satellite systems. In this spectral region, daytime satellite-observed radiances include contributions from both the reflected solar radiation and the emitted thermal emission. In particular, typical stratus and fog clouds posess near-infrared emissivities less than unity, which requires special processing to account for the angular dependence of the solar reflection. In this paper, a side-by-side comparison of time-coincident GOES- and AVHRR-derived near-infrared cloud reflectance is carried out in order to demonstrate the capability of GOES-8 and -9 in both identifying and characterizing the microphysics of stratus and fog clouds during the daytime. The authors first present the mathematical formalism and then apply the technique to extract the near-infrared reflectances from GOES-8 and -9 data. The technique is applicable for operational usage and requires a lookup table to account for the continuously changing sun-satellite viewing geometry. Near-infrared cloud reflectances are extracted from coincident GOES-9 and AVHRR data from both NOAA-14 and -12 for different times of day and are verified against theoretical reflectances derived from radiative transfer theory and previously published results. A retrieval of the cloud drop size distribution effective radius is demonstrated on satellite data along coastal California during the summer of 1996.