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Reprocessed constant calibration L1c OTT drift study. 13 April 2011. ARGANS & L2OS ESL. ascending descending. Reprocessed constant calibration L1c OTT. L1c reprocessed constant calibration data: pre-select South Pacific half-orbits:
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Reprocessed constant calibration L1c OTT drift study 13 April 2011 ARGANS & L2OS ESL ascending descending
Reprocessed constant calibration L1c OTT L1c reprocessed constant calibration data: pre-select South Pacific half-orbits: > 2000 grid points in region latitude -30 to 0, longitude -130 to -120 select one half orbit at 6 day intervals: January - December 2010 sub-set ascending (58) & descending (58) orbits OTT1 made using L2OS v500 candidate & compareTBs v1.3, latitude -50 to +10 snaps filtered for: far from land, sun/galactic glint, tec gradient > 20 +0.5 K drift = -1 psu
Drift: -0.5 K pa in HH & VV, ascending orbits L2OS galactic model error: -1K in HH
Drift: +0.5 K pa in HH & VV, descending orbits L2OS galactic model error: +1K in HH & VV
Drift -0.5 K pa in HH & VV, same as AFFOV But HH bias now higher then VV (opposite to AFFOV), & unexplained low VV January – end March
Drift +0.5 K pa in HH & VV, same as AFFOV But HH bias now higher then VV (opposite to AFFOV), & unexplained low HH & VV January – end March
OTT anomaly 20101104T020829 reversed HH & VV bias – why?
Cross-pol OTT drifts different from HH & VV in AF & EAF ascending descending
ascending descending Descending OTTs show sun alias moving along AFFOV/EAFFOV hexagon
orbit 20101110T013458_20101110T022859 OTT2 from L1B OTT1 from L1C OTTs from L1B (Joe) & L1C (ARGANS) visual match XX/HH YY/VV
Conclusions • reprocessed constant calibration data allows identification of long-term drift • ESL recommendation for 2011 reprocessing • long-term drift: • -0.5 K pa in HH & VV, ascending orbits • +0.5 K pa in HH & VV, descending orbits • cross-pol noise/errors? • sun aliases in EAFOV? • L2OS work • correct galactic model error ±1 K • why short-term OTT irregularities? • refine OTT generation procedures
Extra slides follow, showing • short integration time OTTs close to long • median OTTs different from mean • impact on OTT quality from too few snapshots
tec gradient filter > 5 tec gradient filter > 20 TEC filter reduces number of snapshots: 21 snapshots (left), 210 (right)