Evaluation of Satellite-Derived Sea Surface Temperatures in Tropical Cyclones

Tropical cyclones (TC) rely on the ocean as a main heat source to help fuel their development. TCs extract this energy through fluxes of latent and sensible heat at the air-sea interface. Since obtaining direct flux estimates is extremely difficult because of the current limitations of direct flux instrumentation in the extreme environment of a TC, air-sea flux is commonly estimated through a bulk derivation that relies on sea surface temperature (SST). While SST is more commonly observed in TCs compared to direct flux, direct measurements of SST are still costly to obtain resulting in relatively less observations compared to satellite counterparts. SSTs in TCs are commonly obtained using satellite data, ocean profiling floats (e.g. Argo), ocean gliders, surface drifters, and expendable profilers deployed from aircraft. While the latter four instrument types provide direct observations of SST, a coordinated effort must exist to deploy these into a TC environment or through chance encounters with a passing storm. Satellite data is globally available with high spatial resolution but the temporally blended-nature of these satellite products may miss SST changes in the dynamic TC environment and may have inherent bias due to cloud contamination of particular wavelengths (e.g. infrared). There have been case-by-case assessments of SST in TC environments but literature is lacking a comprehensive assessment of various SST products to direct observations. Recently, a dataset utilizing aircraft expendable bathythermographs (AXBTs) was compiled that captures over 8 years’ worth and nearly 1500 observations of SST in TC environments. Thus, it is advantageous to examine how SST observed in these data compare to various satellite-derived SST products to identify the bias of using each product. While a few studies have compared satellite SST products to these types of SST measurements, it has not been done to this magnitude. This evaluation should be helpful for those wishing to utilize satellite SST in TC applications when there are minimal direct observations available.