ECOSTRESS: calibration and validation during the first-year in orbit
Abstract
The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) addresses questions from three overarching science questions: How is the terrestrial biosphere responding to changes in water availability? How do changes in diurnal vegetation water stress impact the global carbon cycle? Can agricultural vulnerability be reduced through advanced monitoring of agricultural water consumptive use and improved drought estimation? The ECOSTRESS mission will answer these questions by accurately measuring the temperature of plants from the space station over a diurnal cycle throughout the year. The space station's nodal precession of approximately 63 days gives it a variable overpass time and relatively high repeat rate which allows the effective diurnal cycle to be captured over a growing season.
Remote sensing of temperature with ECOSTRESS requires accurate knowledge of the instrument performance parameters such as radiometric sensitivity, spectral response, and geometrical uniformity. The geometrical uniformity is particularly important for ECOSTRESS, since objects end up with different viewing angles depending on the particular overpass as compared to a sun-synchronous orbit. The imaging radiometer has now completed its first year on orbit, and we examine how the calibration and validation have held up from an instrument perspective. This includes temperature retrievals from ground validations sites, such as Lake Tahoe and Salton Sea, as well as the on-board calibration. Ground validation using these sites has shown retrievals to within 1K of absolute temperature. ECOSTRESS uses two newly developed high emissivity blackbodies. Thermal radiation at approximately 20C and 46C are captured for every line scan (approximately every 1.7 seconds). This is used to convert digital numbers to radiance using an affine transform. Monitoring the emission of the blackbodies relative to the embedded temperature sensors has shown consistent calibration performance over the first year.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A33L2947J
- Keywords:
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- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES;
- 0520 Data analysis: algorithms and implementation;
- COMPUTATIONAL GEOPHYSICS;
- 1855 Remote sensing;
- HYDROLOGY;
- 6969 Remote sensing;
- RADIO SCIENCE