Comparison of Altimeter Derived and In-Situ Hurricane Heat Potential

Hurricanes are amongst the most destructive natural disasters known to mankind. The primary energy source driving these storms is the latent heat release due to the condensation of water vapor, which ultimately comes from the ocean. While the Sea Surface Temperature (SST) has a direct correlation with wind speeds, the oceanic heat content is dependent on the upper ocean vertical structure. Understanding the impact of these factors in the mutual interaction of hurricane-ocean is critical to more accurately forecasting intensity change in land-falling hurricanes. Use of hurricane heat content derived from the satellite radar altimeter measurements of sea surface height has been shown to improve intensity prediction.

The general approach of estimating ocean heat content uses a two-layer model representing the ocean with the anomalies from the altimeter. Due to the nature of the two-layer approach, past comparisons with observations have shown an underestimation of the heat content with respect to the 26 deg isotherm particularly in the higher heat content regimes. As part of the global Argo effort, more than 3000 profiling floats acquire temperature and salinity vertical structure over vast regions of world's ocean, resulting in over 350,000 individual profiles. A subset of these profiles is used for comparison to Altimeter derived tropical cyclone heat content. In this paper, a systematic comparison of the satellite altimeter derived heat content using the two layer model with the profiling float observed values is performed globally to identify systematic trends (or underestimates) in the satellite derived values. Given the higher probability of rapid tropical cyclone intensification over regions of high heat content, our goal is to quantify these trends in different ocean basins. The results from this comparison will be presented in this paper. Multiple approaches in improving the hurricane heat content estimates are developed and compared to heat content from fully data assimilative ocean models.