Observation of Tropical Cyclone Self-Induced Barrier Layer

Tuesday, 19 April 2016
Plaza Grand Ballroom (The Condado Hilton Plaza)
John Daniel Steffen, Florida State University/Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL; and S. Chen, L. K. Shay, and B. Jaimes

Analysis of 153 in situ ocean profiles influenced by three hurricanes – Isaac (category 1), Iselle (category 4), and Julio (category 3) – reveals that these hurricanes can create their own salinity-driven ocean barrier layer from heavy precipitation. The freshening of salinity that results from 150-300 mm of rainfall in these hurricanes is about 0.1-0.2 PSU. Eastern Pacific Argo floats near the tracks of Iselle and Julio indicate the barrier layer potential energy (BLPE) values are between 750- 2000 J/m² just after tropical cyclone (TC) passage. AXCTD profiles deployed before, during, and after Isaac in the Gulf of Mexico show how the barrier layer develops throughout a TC passage. In these TCs, the corresponding maximum barrier depths are 10-20 m deep and are independent of density stratification within the isothermal layer. This suggests BLPE is a better measure of barrier layers' capacity to suppress mixing and minimize SST cooling from hurricanes.
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