simulating the consequence of cloud cover on Earth-viewing space missions

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  • 1 NASA-Marshall Space Flight Center, Alabama
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The consequence of cloud cover on Earth-photographing space missions is evaluated by a Monte-Carlo computer simulation procedure using the world-wide cloud cover statistics. These cloud data contain probability distributions for five cloud-cover categories arranged by monthly and three-hourly reference periods. To account for cloud persistence, spatial and temporal probability values are included.

Random numbers are used to select, from the appropriate probability distribution, a cloud-cover category for each satellite pass. The increments of area photographed on each pass, also selected by random numbers, are then pieced together in a mosaic. It is shown by a combinatorial analysis that, for a very cloudy region, over 100 independent satellite passes might be required to find one pass with clouds suitable for photographing a 100 NM diameter area. The computer simulation results indicated that, by accepting incremental photographic coverage, the same area can be acquired in approximately 10 passes.

Simulation results are given for a specified percentage of the target area and for a specified satellite pass number.

1 Presented at the National Meeting of the American Astronautical Society at the New Mexico State University, October 23–25, 1969.

The consequence of cloud cover on Earth-photographing space missions is evaluated by a Monte-Carlo computer simulation procedure using the world-wide cloud cover statistics. These cloud data contain probability distributions for five cloud-cover categories arranged by monthly and three-hourly reference periods. To account for cloud persistence, spatial and temporal probability values are included.

Random numbers are used to select, from the appropriate probability distribution, a cloud-cover category for each satellite pass. The increments of area photographed on each pass, also selected by random numbers, are then pieced together in a mosaic. It is shown by a combinatorial analysis that, for a very cloudy region, over 100 independent satellite passes might be required to find one pass with clouds suitable for photographing a 100 NM diameter area. The computer simulation results indicated that, by accepting incremental photographic coverage, the same area can be acquired in approximately 10 passes.

Simulation results are given for a specified percentage of the target area and for a specified satellite pass number.

1 Presented at the National Meeting of the American Astronautical Society at the New Mexico State University, October 23–25, 1969.

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