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 35潤・south 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.
| Time: | Dec. 29, 1999, 17UTC - Jan. 2, 2000, 12UTC |
| Area: | 34.5潤餞 - 35潤餞 in latitude |
| Product: | 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)2A21 cannot calculate surface scattering cross section(σ0)[sigma zero]. There is a possibility that the obtained σ0[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.
2A25 does not calculate if "BinSurfPeak" in 2B21 is -9999. But the data with weaker σ0[sigma zero] may contain error.
Since the level 3 products are statistic data, level 3 products are affected indirectly with missing data.
For more information, contact to:
Dr. Nobuhiro Takahashi
NASDA/EOSD
World Trade Center Bldg.
2-4-1 Hamamatsu-cho, Minato-ku Tokyo, JAPANphone: +81-3-3438-6352
email: trmmcont@eorc.jaxa.jp