An examination of the spatial and temporal extent of the climate memory of tropical cyclones

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Tuesday, 19 January 2010
Benjamin Schenkel, Florida State University, Tallahassee, FL; and R. Hart

Handout (1.3 MB)

Knowledge of the role of tropical cyclones (TCs) in the climate is crucial towards predicting their future frequency and intensity in a warming world. Hart et al. (2007) provided the first attempt at quantifying the TC-induced stabilization of the atmospheric-oceanic system that occurs due to the cooling of the ocean and warming of the atmosphere. Following in the footsteps of this prior work, this study will serve as an extension to Hart et al. (2007) in both time and space. The impact of TCs upon the climate is evaluated using standard atmosphere and ocean metrics as well as maximum potential intensity (MPI; Emanuel 1987). Anomalies are computed relative to climatology and composited by TC intensity, latitude, ocean basin, and time of year. The sensitivity of these results to the use of different atmospheric reanalysis datasets is also evaluated.

The spatial extent of the positive local MPI anomaly is found to be primarily influenced by the cooling of the ocean whose slow dynamic response allows for the oceanic memory of TCs to be longer. Storm relative sea surface temperature (SST) spatial anomalies, rotated to account for storm motion, show maximum SST cooling to the right of track on day 4 relative to TC passage with SST anomalies lasting up to 60 days or more. The restoration timescale of the SST anomaly was found to be longer than was previously stated in Hart et al. (2007). Positive storm relative atmospheric thickness anomalies are maximized on day 0 with areal coverage that is more symmetric and temporally transient than the oceanic anomalies.