Satellite studies during the 1976-77, 1977-78 Sierra Cooperative Pilot Project: final report to the Office of Atmospheric Resources Management, Bureau of Reclamation
Date
1979-02
Authors
Morris, K. Robert, author
Reynolds, David W., author
Vonder Haar, Thomas H., author
Department of Atmospheric Science, Colorado State University, publisher
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Abstract
Digital imagery from the SMS-2 geostationary satellite was recorded for analysis in support of the Sierra Cooperative Pilot Project. Imagery of five storms during the 1976-77 and 1977-78 seasons of the project have been analyzed in detail using the CSU ADVISAR. Temporal variations in cloud top temperature were charted and synoptic and mesoscale cloud features have been studied. Results show the highest precipitation and lowest cloud top temperatures below -35°C, occur about one or two hours ahead of the surfacecold front within the frontal band. Following the frontal passage an unstable convective orographic cloud remains over the Sierra for up to 8 hours with cloud top temperatures around -15°C well within the seeding window range. Mesoscale features including banded and cellular convection and cloud streets have been observed by the satellite with their effects often showing up in the precipitation gage records. Large convective lines and cells were tracked onshore and were found to move with the winds somewhat below the 50 kPa level. Cells intensify in the Central Valley of California usually dissipating as they climb the Sierra Trajectories of large cells curve to the left upon encountering the foothills becoming nearly parallel to the mountains under certain conditions. Precipitation is greatest on the west slopes of the Sierra due to the orographic effect. Lee-side precipitation appears to be dependent on the presence of high cold cloud tops which lead to precipitation particles being carried over the crest.
Description
February 1979.
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Subject
Clouds -- Photographs from space
Meteorological satellites