Upper Oceanic Energy Response to Tropical Cyclone Passage
NAVAL RESEARCH LAB MONTEREY CA
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The upper oceanic temporal response to tropical cyclone TC passage is investigated using a 6-yr daily record of data-driven analyses of two measures of upper ocean energy content based on the U.S. Navy s Coupled Ocean Data Assimilation System and TC best-track records. Composite analyses of these data at points along theTC track are used to investigate the type, magnitude, and persistence of upper ocean response to TC passage, and to infer relationships between routinely available TC information and the upper ocean response. Upper oceanic energy decreases in these metrics are shown to persist for at least 30 days long enough to possibly affect future TCs. Results also indicate that TC kinetic energy KE should be considered when assessing TC impacts on the upper ocean, and that existing TC best-track structure information, which is used here to estimate KE, is sufficient for such endeavors. Analyses also lead to recommendations concerning metrics of upper ocean energy. Finally, parameterizations for the lagged, along-track, upper ocean response to TC passage are developed. These show that the sea surface temperature SST is best related to the KE and the latitude whereas the upper ocean energy is a function of KE, initial upper ocean energy conditions, and translation speed. These parameterizations imply that the 10-day lagged SST cooling is approximately 0.7degC for a typical TC at 30deg latitude, whereas the same storm results in 10-day 30-day lagged decreases of upper oceanic energy by about 12 7 kJ cm22 and a 0.58degC 0.3 degC cooling of the top 100 m of ocean.
- Physical and Dynamic Oceanography