P2.19
ENSO in Highly Reflective Cloud: A fresh look
David W. Martin, SSEC/Univ. of Wisconsin, Madison, WI; and C. C. Collimore and M. H. Hitchman
A time series of a modified version of Garcia's record of Highly Reflective Cloud, or HRC, prompted concern about their robustness. As modified, did HRC lack even the strongest of interannual signals? To answer this question a two-part test of HRC was designed. Both parts address the presence of El Nino/Southern Oscillation, or ENSO. Both parts treat an equatorial block covering the western Pacific Ocean. The first part of the test compares HRC with published maps of ENSO rainfall. Separately, HRC is composited for El Niņo events and for La Niņa events. The second test compares a subset of the HRC data with a NASA record of Outgoing Longwave Radiation (OLR). For each record the composite procedure is repeated. In both part-one composites dipoles are found. But the dipoles dip in opposite directions: La Niņa, toward the east-southeast; El Niņo, toward the west-northwest. In respect to these dipoles, the pair of HRC anomaly maps closely resembles the ENSO rain maps. Expressed as maps, the part-two dipole signature is stronger in OLR than in HRC. However, expressed as area-averaged values, it is weaker. Compositing answers the question negatively. Far from lacking the strongest of the interannual signals, the Garcia/Waliser/Zhou record of HRC contains a robust ENSO. Compositing also indicates in HRC at least as strong an ENSO signal as in NASA OLR.
Poster Session 2, Climatology and Long-term Satellite Studies
Monday, 15 October 2001, 2:15 PM-4:00 PM
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