Changes in Tropical Rainfall Measuring Mission (TRMM) retrievals due to the orbit boost estimated from rain gauge data
During the first three-and-a-half years of the Tropical Rainfall Measuring Mission (TRMM), the TRMM satellite operated at a nominal altitude of 350 km. To reduce drag, save maneuvering fuel, and prolong the mission lifetime, the orbit was boosted to 403 km in August 2001. The change in orbit altitud...
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| Format: | Others |
| Language: | en_US |
| Published: |
2010
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| Online Access: | http://hdl.handle.net/1969.1/ETD-TAMU-1732 http://hdl.handle.net/1969.1/ETD-TAMU-1732 |
| Summary: | During the first three-and-a-half years of the Tropical Rainfall Measuring Mission
(TRMM), the TRMM satellite operated at a nominal altitude of 350 km. To reduce
drag, save maneuvering fuel, and prolong the mission lifetime, the orbit was boosted
to 403 km in August 2001. The change in orbit altitude produced small changes in a
wide range of observing parameters, including field-of-view size and viewing angles.
Due to natural climatic variability, it is not possible to evaluate possible changes in
precipitation retrievals from the satellite data alone. We estimate changes in TRMM
Microwave Imager (TMI) and the Precipitation Radar (PR) precipitation retrievals
due to the orbit boost by comparing them with surface rain gauges on ocean buoys
operated by the NOAA Pacific Marine Environment Laboratory (PMEL). For each
rain gauge, we compute the bias between the satellite and the gauge for pre- and
post-boost time periods. For the TMI, the satellite is biased ~12% low relative to
the gauges during the pre-boost period and ~1.5% low during the post-boost period.
The mean change in bias relative to the gauges is approximately 0.4 mm day^-1. The
PR is biased significantly low relative to the gauges during both boost periods. The
change in bias is rain rate dependent, with larger changes in areas with higher mean
precipitation rates. |
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