Oceanography SeminarMarch 14, 3:00pm - 4:15pm
Mānoa Campus, MSB 100
Graduate School of Oceanography
University of Rhode Island
Cumulative effect of tropical cyclones on the ocean: A numerical modeling study
Abstract: Strong surface winds of a tropical cyclone locally cool the surface and warm the subsurface waters via turbulent mixing processes. For individual TCs the response of local ocean temperatures to the surface wind field has been well described via observations and models. However, the cumulative effect of TCs on the ocean remains largely unanswered. While the surface cool anomalies may decay on scales of days/weeks, the subsurface anomalies persist much longer. Recent studies suggest that the TC-induced ocean mixing can have global climate impacts, including changes in poleward heat transport, ocean circulation and thermal structure. In several of the modeling studies devoted to this problem, the TC mixing has been treated as an idealized source of additional vertical diffusion in the upper ocean. In contrast, this study aims to explicitly resolve tropical cyclone forcing using a high-resolution global ocean model as a tool for developing a systematic understanding and quantification of the processes associated with the climatic impacts of TCs.
Simulations of the 2004 and 2005 tropical cyclones in all ocean basins are conducted using NOAA GFDL's Modular Ocean Model 4 with 25 km grid spacing. These simulations are carried out with and without the inclusion of tropical wind forcing, blended with the daily NCAR heat and momentum fluxes. Tropical cyclones are generated from the best track dataset. I will discuss the spatial extend and magnitude of tropical cyclone forced sea surface temperature, ocean heat lost and subsurface warm anomalies over the course of a hurricane season and estimations of the contribution of these anomalies to the global and regional ocean heat content.
Oceanography, Mānoa Campus