ECOSTRESS and CIMIS: A Comparison of Potential and Reference Evapotranspiration in Riverside County, California
Abstract
The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) mission, an earth-imaging thermal instrument on the International Space Station, provides measurements of plant water stress at 70 m spatial resolution and temporal revisits of 1-5 days. This study, in partnership with the Eastern Municipal Water District (EMWD) in Southern California, was conducted to evaluate estimates of evapotranspiration under ideal conditions where water is not a limiting factor, called potential evapotranspiration (PET) or reference evapotranspiration (ETo). EMWD regularly uses a ground-based network of ETo estimates from the California Irrigation Management Information System (CIMIS), yet there are gaps in spatial coverage and questions of spatial representativeness. Space-based PET estimates, such as those from ECOSTRESS, could provide consistent wall-to-wall coverage. As such, we compared ECOSTRESS PET to CIMIS ETo at five CIMIS sites in Riverside County, California from July 2018 - June 2020. We found strong correlations between CIMIS ETo and ECOSTRESS PET across all sites (R2 = 0.82, N = 285, NRMSE = 0.14). ECOSTRESS samples the diurnal cycle, and we found that it successfully captures diurnal and seasonal patterns. However, despite the strong correlations, at some stations ECOSTRESS and CIMIS were offset from one another by an average 14%. Many of the CIMIS stations are in highly heterogeneous areas, causing the pixel-to-station matchup to include sub-pixel contamination. Consequently, careful examination of CIMIS landscapes must be considered in future comparisons. These results suggest that ECOSTRESS PET is comparable to reference ET, across spatial scales enabled by ECOSTRESS measurements.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH038.0010K
- Keywords:
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- 1855 Remote sensing;
- HYDROLOGY;
- 1880 Water management;
- HYDROLOGY;
- 1894 Instruments and techniques: modeling;
- HYDROLOGY;
- 1895 Instruments and techniques: monitoring;
- HYDROLOGY