New MEaSUREs Surface Turbulent Fluxes ESDR Is Now Available

A new Goddard Satellite-based Surface Turbulent Fluxes (GSSTF) ESDR has been released by the GES DISC. The ESDR, GSSTF3, was produced by PI Chung-Lin Shie’s MEaSUREs project “GSSTF Data Set for Global Water and Energy Cycle Research.”Accurate global sea surface flux measurements are crucial to understanding the global water and energy cycles.  Oceanic evaporation, a major component of the global oceanic fresh water flux, is particularly useful for predicting oceanic circulation and transport because it contributes to the net fresh water input to the oceans and drives the upper ocean density structure and consequently the circulation of the oceans. The new GSSFT3 ESDR, using corrected SSM/I TB (removing the impact of drifted Earth incidence angle, EIA) and a newly-updated algorithm for retrieving surface specific humidity (Qair) has reduced the trends of globally-averaged latent heat flux (LHF) from 0.53% (GSSTF2c) to 0.45% per year during the period January 1998 through December 2008. A smaller (less positive or even slightly negative) trend in LHF is considered more consistent with a slightly increasing temporal trend found in the globally averaged air temperature.

The finer spatial resolution (0.25° × 0.25°) of the daily GSSFT3 ESDR (compared to the 1° × 1° resolution of the preceding GSSTF2c) contributes to better understanding of tropical cyclones and hurricanes and their interaction with the ocean. Fully tested, the GSSTF3 product can serve as a crucial input for oceanic data assimilation by general circulation models (GCMs) for forecasting. The daily temporal and 0.25° spatial resolution of the GSSFT3 product can be used to examining climate variability at these scales. The input data sets used in the production of the GSSTF3 ESDR include a recently released NCEP sea surface temperature (SST) analysis, a uniform (across satellites) surface wind and microwave brightness temperature (TB) data set produced by Remote Sensing Systems (RSS) from data from the Special Sensor Microwave Imager (SSM/I) on board the Defense Meteorological Satellite Program (DMSP) satellites.

The figure compares the Global (90°N–90°S) monthly-average time series (1998-2008) of Latent Heat Flux (W m^-2) of GSSTF3 (pink), GSSTF2c (green), GSSTF2b-Set1(red) and GSSTF2b-Set2(blue), showing that GSSTF3 possesses the smallest trend.

The GSSTF3 ESDR is available from the GES DISC, see the website at URL http://disc.sci.gsfc.nasa.gov/datareleases/gsstf-version-3. The site provides a description of the GSSTF3 ESDR and how it may be obtained.