Evolution of Atmosphere and Ocean Boundary Layers from Aircraft Observations and Coupled COAMPS/NCOM
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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Strong offshore winds are frequently observed over the Gulf of Tehuantepec in the eastern Pacific Ocean when synoptic conditions create a cross-isthmus pressure gradient through the Chivela Pass in southern Mexico. During such high wind events, turbulent mixing and upwelling in the upper-ocean can reduce the sea-surface temperature by several degrees within hours of event onset. This research conducts an extensive analysis of aircraft measurements from the 2004 Gulf of Tehuantepec Experiment GOTEX. Combined with coupled COAMPSNCOM simulations, this research provides new insight into the spatial and temporal evolution of the marine and atmospheric boundary layers during outflow events. Three regions within the outflow are identified with distinct response characteristics. The addition of COAMPS simulations reveals the three-dimensional variations of the outflow jet not visible from the observations and the presence of a secondary outflow jet to the east that influences the symmetry of the atmospheric forcing. Calculations of the ocean mixed layer heat budget indicate entrainment mixing as the dominant cooling mechanism during outflow events. An evaluation of the fully-coupled model reveals minimal improvement in wind speed and stress, temperature, and moisture, but shows the greatest improvement in the air-sea temperature difference and surface sensible and latent heat fluxes.
- Physical and Dynamic Oceanography