FY 2011
Upper-ocean response to Typhoon Choi-Wan as measured by the Kuroshio Extension Observatory (KEO) mooring
Bond, N.A., M.F. Cronin, C. Sabine, Y. Kawai, H. Ichikawa, P. Freitag, and K. Ronnholm
J. Geophys. Res., 116, C02031, doi: 10.1029/2010JC006548, 8 pp (2011) |
| The Kuroshio Extension Observatory (KEO) is a highly instrumented moored reference station located at 32.3°N, 144.5°E in the recirculation gyre south of the Kuroshio Extension. On 19 September 2009, the eye of Typhoon Choi-Wan (International designation: 0914) passed ~40 km to the southeast of the KEO surface mooring. Hourly meteorological and physical oceanographic measurements together with 3 hourly air-sea carbon dioxide observations telemetered from KEO in near real time show the evolution of the upper ocean and its associated air-sea fluxes during the passage of this storm and its aftermath. During the approach of the storm, the mixed layer freshened because of intense rainfall. This was followed by a large outgassing of CO2, rapid cooling, and an increase in salinity. Although these changes in mixed layer properties imply substantial entrainment, they were accompanied by upwelling and ultimately a temporary ~20 m shoaling of the mixed layer. This upwelling, which was observed at all depths, including the deepest sensor near 500 m, was coincident with the onset of near-inertial oscillations in the mixed layer currents. After the typhoon passed, inertial pumping caused ~15–20 m amplitude vertical displacements throughout the top 500 m that continued for at least 6 days. A large oceanic response was observed in this case even though the eye of Choi-Wan passed to the right of KEO, resulting in winds rotating cyclonically with time, in opposition to the anticyclonic-rotating near-inertial currents. |
