This is project is funded by WeatherPredict Consulting
In collaboration with: NOAA/Geophysical Fluid Dynamics Laboratory (GFDL)
With the help of GFDL, we have developed a modeling framework for studying the impact that tropical cyclones have on the global ocean on interseasonal to interannual timescales. Strong surface winds of a hurricane locally cool the surface and warm the subsurface waters via turbulent mixing processes. While surface cool anomalies generally decay in roughly a month, subsurface anomalies can persist over a seasonal cycle, providing a net ocean heat uptake over the course of one to several years.
We use GFDL's MOM4, a global mesoscale eddy permitting ocean circulation model, forced by tropical cyclones blended with the daily CORE atmosphere, to examine questions related to the magnitude and cumulative footprint of subsurface warm anomalies forced by tropical cyclones during the 2004-2005 global tropical cyclone season and beyond.We also consider the time scales over which subsurface heat anomalies decay. Physical characteristics of cyclone-forced surface and subsurface anomalies are elucidated using this model tool. In particular, we examine the spatial extent and magnitude of storm forced subsurface warm anomalies over the entire season.
We estimate the contribution of cyclone-induced anomalies to the ocean heat content and sea surface temperature, and analyze the meridional redistribution of the anomalous heat by ocean circulation, finding that the global ocean has an accumulated heat uptake of approximately 4·1021 J over the course of the year. TC heating was most significant in the North Atlantic and West Pacific, reaching nearly 8% and 7% of the local seasonal upper ocean heat content signal in those respective regions.
Further, the results indicate a convergence of anomalous heating in the equatorial Pacific, leading us to explore the key regions of meridional transport, and hypothesize the possible climate implications of this heat input.