Satelitte-Derived Ocean Heat Content Variability Estimates: Implications for Weather and Climate Studies

A 20-year time series of satellite-derived oceanic heat content (OHC) estimates relative to 26^oC has been generated from quality controlled sea surface height anomaly (SSHA) fields from various missions (e.g., Jason 1-3, Envisat, SARAL, Cryosat-2, Sentinel-3A) cast into a reduced-gravity ocean model and a daily ocean climatology of mean isotherm depths and reduced gravities. Over this time/space series, two or more satellites have been operational at any given time to resolve mesoscale ocean variability. Sea surface temperatures (SST) from Remote Sensing System’s Optimally Interpolated SST and NESDIS SST Analysis represent the surface boundary condition to produce isotherm depths of the 20^o and 26^o (D20, D26), mixed layer depth, and OHC for use weather (tropical cyclone) and climate (ENSO) studies. For the operational product suite, SSHA data from 10 days before the date in question are used. By contrast, the reprocessed data uses SSHA data from 5 days before and 5 days after the date of interest for more detailed research product including those with longer repeat tracks so mesoscale oceanic features were not unnaturally stretched out. The resulting data products date back to 1998 for three basins. As part of the product generation and updating the climatologies, satellite-derived estimates have been compared to over a million in-situ thermal measurements from multiple platforms (e.g., Argo Floats, ship transects, moorings) to assess biases and uncertainties in spaced-based estimates. Central to this assessment is the need for sustained moorings in the tropics that provide the evolving isotherm depths and OHC variations for weather and climate studies..

Implications of OHC variations on recent hurricane passage will be discussed such as Blanca and Patricia in the eastern Pacific Ocean basin in 2015. Prior to these storms, the strong El Nino conditions increased the SSHA by more than 12 cm and the OHC values were nearly twice those under non El Nino conditions.