Assimilating 20 years of Atlantic XBT data into HYCOM: a first look

Expendable bathythermographic (XBT) data for the years 1972–1991 have been assimilated into a Hybrid Coordinate Ocean Model (HYCOM) for the Atlantic Ocean. Climatological salinity profiles were combined with the observed temperature profiles to estimate companion potential-density profiles, which are used to determine the observation-based local structure of the model’s hybrid layers. The model’s density, temperature, and layer-interface-depth fields were corrected monthly via optimal interpolation. Preliminary results presented here show that the data have a major impact on the simulation, correcting model biases, and that the corrections persist between monthly assimilations.