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SST Observations of Tropical Instability Waves. Data Analysis Yang Liu Elizabeth Wong Adam Chambers. Intro to Tropical Instability Waves. A regular pattern of westward propagating waves that form near the equator at the interface between areas of warm and cold sea surface temperatures
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SST Observations of Tropical Instability Waves Data Analysis Yang Liu Elizabeth Wong Adam Chambers
Intro to Tropical Instability Waves • A regular pattern of westward propagating waves that form near the equator at the interface between areas of warm and cold sea surface temperatures • Present in Atlantic, but easier to see in the Pacific • Average period of ~30 days and wavelength of ~1000-2000 km
The Data • Product: Foundation SST • Resolution: ~.09 Degree (~9 kilometer) Gridded (4096 x 2048) • Derived from: MW SSTs (AMSR-E, TMI) and IR (MODIS) SSTs • Time Coverage: Global (90N to 90S): • 2010-Jan-1 through 2011-Jan-1 • IR allows higher spatial resolution, and SST near land. However, IR input is less accurate than MW due to cloud contamination. Blending MW and IR enables greater coverage and higher accuracy than IR only SSTs
Rebinning • Data can resolve small scale features. • By rebinning we see that many small scale features are no longer visible • play movie
Scalefactors Variance decreases as scalefactor increases Data: June, Long: 180W-90W, Lat: -20-20
El Nino and Wind Variability • ENSO has a strong influence on TIW formation • El Nino conditions lessen TIW formation • La Nina conditions strengthen TIW formation SST Anomalies in the Pacific NOAA
High-Pass Filter • Filter used to see SST Anomalies
SST (unfiltered, all of 2010) SST Anomalies (filtered, all of 2010) Phase speed ~0.7m/sec
SST anomaly June 1 2010 SST anomaly June 1 2010 SST anomaly June 1 2010
wavenumber wavenumber wavenumber
Future Work • Studies have linked Tropical Instability Waves to Wind, Water Vapor, and Precipitation (Caltabiano et. al 2005) • Investigate these relationships…
Conclusions • High resolution data was used to study Tropical Instability Waves • TIW most likely to form when trade winds are lessened/reversed in June-September • As suggested by Chelton(2000), TIW more intense in the northern hemisphere • Observed wavelength and period of TIW was ~2000-5000km and ~30 days when analyzed over one day. Similar results were obtained when analyzed over June-December • Understanding the relationship between TIW and wind/water vapor/precipitation will require further investigation