The Evaporative Stress Index (ESI) from GET-D system describes temporal anomalies in evapotranspiration (ET), highlighting areas with anomalously high or low rates of water use across the land surface. Thus, the areas with negative ET anomalies or low rates of water use (usually highlighted with red color) indicate drought occurrence. The ESI also demonstrates capability for capturing early signals of “flash drought," brought on by extended periods of hot, dry, and windy conditions leading to rapid soil moisture depletion. Daily ET from GET-D system is retrieved with the ALEXI model (Anderson et al, 1997) using GOES ABI land surface temperature (LST) product. Science details of the ET retrievals are published in Fang et al (2019). ET and ESI are generated daily from GET-D for CONUS domain at 2km spatial resolution with about one day latency, but only ESI composites of 2, 4, 8 and 12 weeks are posted as drought monitoring data products in this webpage.
Because GOES ABI LST product is available only for clear days without cloud cover, LST observations for cloudy regions or cloudy days for GET-D are to be estimated from Ka-band microwave data acquired by JAXA GCOM-W AMSR2. Preliminary results for the all-weather ET and ESI data are published in Fang et al (2022). Data sets are available could be obtained from STAR GET-D developers (POC: li.fang@noaa.gov or xiwu.zhan@noaa.gov).
Details on how GET-D system generates ET and ESI data products may be found in the GET-D system Algorithm Theoretical Basis Document (ATBD). Science details of the GET-D system were described in Zhan et al (2021).
The NESDIS GET-D product system was operational using NOAA GOES-13/15 observations. It stopped operation after January 8, 2018 when NOAA switched primary operational geostationary satellites from GOES-13 to GOES-16 which uses the Advanced Baseline Imager with better spatial and spectral resolutions. To use ABI observations, GET-D has been upgraded to generated ET and ESI for CONUS with 2km spatial resolution instead of the previous 8km under the NASA ROSES research project. Preliminary ESI data products are posted on this webpage. Science and software architecture details of the upgraded GET-D product system are published in Fang et al (2019) & Fang et al (2022). The upgraded software system will be transitioned to the NESDIS operational platform once supports becomes available.
Anderson, M. C., J. M. Norman, G. R. Diak, W. P. Kustas, and J. R. Mecikalski (1997), A two-source time-integrated model for estimating surface fluxes using thermal infrared remote sensing, Remote Sens. Environ., 60, 195–216, doi: 10.1016/S0034-4257(96)00215-5.
