Modeling the tropical ocean response to westerly wind forcing

Download
Author
Whitney, Claudia S.
Date
1992-12Advisor
Murphree, James Thomas
Garwood, Roland W.
Metadata
Show full item recordAbstract
A primitive equation ocean general circulation model, with
mixed layer physics, has been developed and applied to an
investigation of the equatorial ocean. The major physical
problem addressed with this model is the response of the upper
ocean to westerly wind events, such as those that occur during
tropical cyclones and during El Nino events.
In the model development phase, several configurations of
the mixed layer physics, domain size, and wind stress were
tested. The best overall simulations were produced when both
Richardson number dependent mixing and a bulk mixed layer
model were included. Small model domains were found to be
especially sensitive to the prescribed lateral boundary
conditions and wind stress. Smaller domains required more
realistic wind stress fields in order to achieve reasonable
current structures. In addition, the off-equatorial currents
were particularly responsive to changes in the zonal gradient
of the wind stress. The final configuration of the model
produces realistic simulations of climatological threedimensional
temperature and current structures in the
equatorial ocean.
In the model application phase, synoptically varying winds
for the tropical Pacific were used to force the model. The winds came from the Navy's Operational Global Atmospheric
Prediction System's (NOGAPS) daily analyses for the 1991-92 El
Nino, which included several strong westerly wind events. The
strong temporal and spatial variability in these winds
produced complex fluctuations of the model's temperatures,
currents, and internal waves, including reversals of the South
Equatorial Current and equatorially trapped Kelvin waves.
Model verification was performed by comparison with an
observational study of in situ equatorial Pacific buoy data.
This comparison showed that synoptic scale variations in the
wind stress are needed to simulate the ocean's strong
responses to westerly wind events.
Collections
Related items
Showing items related by title, author, creator and subject.
-
An observational study of the local and remote response of the equatorial Pacific to westerly wind events during the 1991-92 El Nino
Cooper, Grant Alexander, IV (Monterey, California. Naval Postgraduate School, 1992-12);The upper equatorial Pacific Ocean response to anomalous westerly wind forcing during the 1991-92 El Nino was examined using observed oceanographic and atmospheric data from equatorial moorings and the Navy's operational ... -
A Theory for the Tropical Tropospheric Biennial Oscillation
Chang, C.-P.; Li, Tim (2000-07-15);The key questions of how the tropospheric biennial oscillation (TBO) maintains the same phase from northern summer in South Asia to southern summer in Australia, and how the reversed phase can last through three locally ... -
Tropical Circulations Associated with Southwest Monsoon Onset and Westerly Surges over the South China Sea
Chang, C.-P.; Chen, George T.-J. (1995-11);The earliest onset of the Asian summer monsoon occurs in early to middle May over the South China Sea. This onset is signified by the development of low-level westerlies and leads to heavy convective rainfall over southern ...