Investigating tropical cyclone-climate feedbacks using the TRMM Microwave Imager and the Quick Scatterometer

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Abstract

[1] Sea surface temperature (SST) and near-surface winds from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and the Quick Scatterometer (QuikScat) are used to calculate globally integrated tropical cyclone-induced SST anomalies and power dissipation (PD). We estimate tropical cyclone-induced upper ocean cooling to be ∼35% higher than our previous estimates based on reanalyzed ERA40 and NCEP surface data. Annually averaged, global PD estimates from TMI are ∼5 × 1019 J for the years 1998 to 2006 (roughly 30% greater than ERA40 PD for overlapping years). QuikScat PD is estimated to be ∼1.7 × 1020 J for the years 2000 to 2006. On the basis of these results, we conclude that the cyclone-induced cooling signal appears to be underrepresented in ERA40 and NCEP reanalysis, as postulated in recent observational and modeling studies. Furthermore, we observe a strong positive relationship between PD and ocean surface cooling, providing further evidence for the likelihood of cyclone-induced climatic feedbacks. These results support the hypothesis that tropical cyclones play an active role in the tropical surface ocean heat budget by cooling the tropical upper oceans through enhanced vertical mixing, which likely represents a net warming beneath the oceanic mixed layer. Thus, to the degree that vertical mixing is important for regulating the ocean's meridional overturning circulation and poleward heat transport, tropical cyclones may be an important contributor to Earth's climate system. This further confirms the results of Emanuel (2001, 2002) and Sriver and Huber (2007b) that possible future changes in integrated cyclone intensity associated with warmer SST may provide possible climatic feedbacks through enhanced vertical mixing and increased ocean heat transport, thus buffering the tropics to increased temperatures while amplifying the warming at higher latitudes.

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