Physical Oceanography Lunchtime Seminar, Summer 2015

 

Physical Oceanography Lunchtime Seminar, Summer 2015

Special seminars for the Summer Qtr


Next Seminar
hosted by Billy Kessler, NOAA-PMEL

Anomalous Java SST cooling at the initiation of positive Indian Ocean Dipole events

Andrew Delman, Scripps Institution of Oceanography

June 24:  MSB 123 12:30 (note different room!)

Anomalous SST cooling south of the island of Java in austral fall and winter (May-September) is an important precursor to positive Indian Ocean Dipole (IOD) climate events.  The SST anomalies are coincident with seasonal upwelling from southeasterly trade winds, but Kelvin waves and outflows from the Indonesian Seas may modulate the degree of surface cooling that occurs in a given year.  Analyses of satellite datasets over approximately two decades demonstrate that SST anomalies are strongly correlated with remote wind forcing in the equatorial Indian Ocean and near Sumatra, with local winds having little effect on the interannual variability of SST.  To further clarify the remote influences on Java SST, altimetry data is used to compute a Kelvin wave coefficient K that estimates the amplitude of Kelvin waves propagating along the Indian Ocean equatorial-coastal waveguide.  Comparisons of wind forcing and K indices with the Java SST anomaly and IOD index highlight considerable differences between individual positive IOD events.  Nonetheless, all positive IOD years have a preponderance of upwelling-favorable wind forcing and Kelvin waves along the waveguide, which distinguishes them from neutral and negative IOD years.   A proxy index of Lombok Strait flow from altimetry suggests that relatively warm, fresh water from the Indonesian Seas may also have an important impact on SST south of Java.  Implications of this study for IOD predictability and ongoing work with mixed layer budgets in the region from ocean GCMs will also be discussed.
 

Seminar organizer: Susan Hautala, hautala (at) uw.edu.  
For Fall 2015 seminars, please contact Peter Rhines, rhines (at) ocean.washington.edu

(The schedule of future seminar organizers can be found here.)

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