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Boreal summer intraseasonal SST variability in the tropical eastern north Pacific
Eric D. Maloney, Oregon State Univ., Corvallis, OR; and D. B. Chelton and S. Esbensen
Boreal summer intraseasonal (30-90 day timescale) SST variability in the east Pacific warm pool is examined using Tropical Rainfall Measuring Mission Microwave Imager sea surface temperatures (SSTs) during 1998-2005. Intraseasonal SST variance maximizes at two locations in the warm pool: in the vicinity of 9°N, 92°W near the Costa Rica Dome, and near the northern edge of the warm pool in the vicinity of 19°N, 108°W. Both locations contain a significant spectral peak at 50-60 day periods, timescales characteristic of the Madden-Julian oscillation (MJO). Complex empirical orthogonal function (CEOF) and spectra coherence analyses are used to show that boreal summer intraseasonal SST anomalies are coherent with precipitation anomalies across the east Pacific warm pool. Spatial variations of phase are modest across the warm pool, although some evidence exists for northward progression of intraseasonal SST and precipitation anomalies. Intraseasonal SSTs at the north edge of the warm pool lag those in the vicinity of the Costa Rica Dome by about one week.
The MJO explains 30-40% of the variance of intraseasonal SST anomalies in the east Pacific warm pool during boreal summer. Peak-to-peak SST variations of about 1.0°C occur during MJO events. SST is approximately in quadrature with MJO precipitation, with suppressed (enhanced) MJO precipitation anomalies leading positive (negative) SST anomalies by 7-10 days. Consistent with the CEOF and coherence analyses, MJO-related SST and precipitation anomalies near the Costa Rica Dome lead those at the northern edge of the warm pool by about a week.
Session 1, Coupled ocean-atmosphere interactions and their contribution to climate variability on all time scales (Part I)
Monday, 20 August 2007, 9:00 AM-10:30 AM, Broadway-Weidler-Halsey
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