HR: 1300h
AN: OS52D-14    [PDF]
TI: Empirical Orthogonal Function Analysis of Sea Surface Temperature in the Arabian Sea: `A Cloud Free Vision'
AU: * BaMasoud, A
EM: bamasoud@apl.washington.edu
AF: Applied Physics Lab, Univ of Washington, 1013 40th st NE, Seattle, WA 98105 United States
AU: Lee, C
EM: Craig@apl.washington.edu
AF: Applied Physics Lab, Univ of Washington, 1013 40th st NE, Seattle, WA 98105 United States
AU: Kelly, K
EM: kkelly@apl.washington.edu
AF: Applied Physics Lab, Univ of Washington, 1013 40th st NE, Seattle, WA 98105 United States
AB: Relative to previous investigation based on Advanced Very High Resolution Radiometer (AVHRR) derived Sea Surface Temperatures (SSTs) (Wilson-Diaz et al., 2001), a new Empirical Orthogonal Function (EOF) analysis employing cloud-free SST maps of the Arabian Sea finds larger amplitude SST variability and identifies patterns associated with the Monsoonal cycle. The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) provides cloud-free daily Sea Surface Temperature (TMI/SST) measurements in all weather conditions except rain. Persistent Summer Monsoon cloud cover hampered previous studies, limiting data availability during this period of large amplitude SST fluctuations and strong lateral SST gradients. TRMM's cloud-penetrating ability facilitates a more complete characterization of Monsoonal variability. EOF analysis of 607 SST maps (0-25N, 40-70E, 1998 thru 2002) is performed twice, with and without the seasonal cycles. When analysis is performed without removing the seasonal cycle, the first mode explains 59.9\% of the SST variability and is consistent with a response to the semi-annual Indian Monsoon. The second mode explains 21.2\% of the SST variability and is identified as the annual radiative heat flux cycle. Mode two spatial amplitude has opposing signs in Gulf of Aden and the northeast Arabian Sea relative to the Somali coast. The third mode, though not statistically significant, exhibits patterns that are consistent with observations of cool filaments extending from the Omani coast during the Summer Monsoon. When the seasonal cycle is removed from the timeseries at each pixel and the EOF analysis is repeated, the first mode shows an anomalous 1 C rise in 1998 basin-averaged SST, possibly associated with 97/98 ENSO event. A positive trend follows, with basin average SST rising 0.47 C from 2000 thru 2002. QSCAT wind stress daily maps (July 1999-July 2003, same region) are also analyzed using complex EOF technique to identify the SST response to wind forcing.
DE: 4279 Upwelling and convergences
DE: 4572 Upper ocean processes
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting