The GOES I–M Imagers: New Tools for Studying Microphysical Properties of Boundary Layer Stratiform Clouds

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This study reviews the capability of the advanced imagers on Geostationary Operational Environmental Satellites (GOES) I–M to provide quantitative information about bulk microphysical properties of low-level stratiform clouds, namely, cloud liquid water path (LWP) and droplet effective radius (re). Previous studies show that accurate estimates of cloud LWP from GOES imagers are possible, as evaluated from both ground-based and spaceborne passive microwave measurements, provided care is taken in vicarious calibration of the visible channel. GOES estimates of re have yet to be validated. However, the re versus LWP relationship derived from GOES and Special Sensor Microwave/Imager data shows good agreement with theory. The unique high-temporal sampling of the imager allows for detailed study of daytime characteristics of cloud microphysical properties and, possibly, indirect aerosol effect. Microphysical information for drizzling marine stratocumuli was also obtained, which was confirmed by direct comparison to ship-based C-band radar during the 1997 Tropical Eastern Pacific Process Study. From the promising results obtained thus far, GOES I–M imager data should be of great value in future field experiments involving low-level stratiform clouds.

*Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, Colorado.

+Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama.

Corresponding author address: Dr. Thomas J. Greenwald, Cooperative Institute for Research in the Atmosphere, Colorado State University, Foothills Campus, Fort Collins, CO 80523-1375. E-mail: greenwald@cira.colostate.edu

This study reviews the capability of the advanced imagers on Geostationary Operational Environmental Satellites (GOES) I–M to provide quantitative information about bulk microphysical properties of low-level stratiform clouds, namely, cloud liquid water path (LWP) and droplet effective radius (re). Previous studies show that accurate estimates of cloud LWP from GOES imagers are possible, as evaluated from both ground-based and spaceborne passive microwave measurements, provided care is taken in vicarious calibration of the visible channel. GOES estimates of re have yet to be validated. However, the re versus LWP relationship derived from GOES and Special Sensor Microwave/Imager data shows good agreement with theory. The unique high-temporal sampling of the imager allows for detailed study of daytime characteristics of cloud microphysical properties and, possibly, indirect aerosol effect. Microphysical information for drizzling marine stratocumuli was also obtained, which was confirmed by direct comparison to ship-based C-band radar during the 1997 Tropical Eastern Pacific Process Study. From the promising results obtained thus far, GOES I–M imager data should be of great value in future field experiments involving low-level stratiform clouds.

*Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, Colorado.

+Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama.

Corresponding author address: Dr. Thomas J. Greenwald, Cooperative Institute for Research in the Atmosphere, Colorado State University, Foothills Campus, Fort Collins, CO 80523-1375. E-mail: greenwald@cira.colostate.edu
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