The cold wake of typhoon Chaba (2010)

The cold wake of typhoon Chaba (2010) is investigated using an array of temperature sensors connected from the surface to 540 m along the mooring line of an air-sea interaction buoy. Initially, surface forcing caused upper ocean water to entrain across the base of the thermocline, producing a mixed layer cooling and subthermocline warming between 42 and 100 m. However, this warm layer lasted just 12 h before it became overwhelmed by an upwelling of cold water. Observations indicate this upwelling occurred to at least 540 m while further analysis suggests that the actual depth of the ocean response to Chaba was closer to 700 m. This caused a massive reduction in heat content at the mooring site. The sea surface temperature decreased 2.5 °C. Due to the lateness of the season, the ocean didn't recover to its pre-typhoon state, however, after sixteen days it did match the temperature outside the wake. These observations reveal intricate processes in a cold wake that redistribute heat between the mixed layer, the subthermocline region, and greater depths. This has implications for tropical storm intensity-by altering enthalpy fluxes, and climate-through the lateral and vertical movement of water which modifies the local temperature profile and impacts the transportation of heat to high latitudes.