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On the TRMM / PR data after special Maneuver (Dec. 29, 1999)
NASA TRMM/FOT performed special maneuver of TRMM satellite on December 29, 1999. As a result of this maneuver, spacecraft altitude exceeded the nominal PR
observation range (350+-1.25km). This caused to fail the earth surface detection algorithm around 35Esouth in latitude where the distance between earth geoid
and the spacecraft becomes maximum. This failure causes algorithms of TRMM/PR. This report, summarizes the influences of this special maneuver on PR product.
Dec. 29, 1999, 17UTC - Jan. 2, 2000, 12UTC
34.5 S - 35 S in latitude
1B21, 1C21, 2A21, 2A25 (Missing except for nadir data) 3A25, 3A26 (indirectly affected)
Characteristics of missing (unreliable) data:
"BinSurfPeak" in 1B21 is -9999 "MinEchoFlag" in 1B21 is 0 (No Rain)
cannot calculate surface scattering cross section(Ð0)[sigma zero]. There is a possibility that the obtained Ð0[sigma zero] is weaker than
typical value because of the failure to detect the true surface peak. This would be a error in 2A21 data, but no indication appears.
does not calculate if "BinSurfPeak" in 2B21 is -9999. But the data with weaker Ð0[sigma zero] may contain error. Since the level 3 products are statistic data, level 3 products are affected indirectly with missing data.