ECOSTRESS Evaporative Stress Index dis-ALEXI USDA Daily L4 Global 30 m

PI: Simon Hook, Martha Anderson


The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) mission measures the temperature of plants to better understand how much water plants need and how they respond to stress. ECOSTRESS is attached to the International Space Station (ISS) and collects data over the conterminous United States (CONUS) as well as key biomes and agricultural zones around the world and selected FLUXNET validation sites. A map of the acquisition coverage can be found on the ECOSTRESS website.

The United States Department of Agriculture (USDA) ECO4ESIALEXIU Version 1 data product provides the Evaporative Stress Index (ESI), which is computed from clear-sky estimates of the relative daily evapotranspiration (ET) fraction: ESI = ET/ETo, where ET is ETdaily from the ECOSTRESS Level 3 product and ETo is the reference ET. A description of the major components of the ECOSTRESS algorithm implemented in Version 1 of the Atmosphere Land Exchange Inverse (ALEXI) Disaggregation algorithm (DisALEXI) ESI code is provided in the Algorithm Theoretical Basis Document (ATBD). ESI applications include indicating agricultural drought and observing vegetation stress. The dis-ALEXI USDA ESI product is generated on a UTM grid at a spatial resolution of 30 meters.

The ECO4ESIALEXIU Version 1 data product contains layers of daily evaporative stress index, evaporative stress index uncertainty, and associated quality flags. A low-resolution browse is also available showing daily ESI as a stretched image with a color ramp in JPEG format.

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Collection and Granule


Characteristic Description
File Size~80 MB
Temporal ResolutionVaries
Temporal Extent2018-07-30 to Present
Spatial ExtentCONUS, key biomes/agricultural zones, selected FLUXNET sites
Coordinate SystemUniversal Transverse Mercator (UTM)
DatumWorld Geodetic System (WGS84)
File FormatHDF5
Geographic Dimensions90 km x 90 km


Characteristic Description
Number of Science Dataset (SDS) Layers3
Columns/Rows3000 x 3000
Pixel Size30 m


SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
ESIdaily Evaporative Stress Index Daily mm/day 32-bit floating point -9999 N/A 0 to 30 N/A
ESIdailyUncertainty Evaporative Stress Index Daily Uncertainty mm/day 32-bit floating point -9999 N/A 0 to 30 N/A
QualityFlag Quality Flag N/A 8-bit unsigned integer -9999 N/A 0 to 15 N/A

Product Quality

Quality information for the ECO4ESIALEXIU Version 1 data product is provided in section 2.4 of the User Guide.

Known Issues

  • Data acquisition gaps: ECOSTRESS was launched on June 29, 2018 and moved to autonomous science operations on August 20, 2018 following a successful in-orbit checkout period. On September 29, 2018, ECOSTRESS experienced an anomaly with its primary mass storage unit (MSU). ECOSTRESS has a primary and secondary MSU (A and B). On December 5, 2018, the instrument was switched to the secondary MSU and science operations resumed. On March 14, 2019, the secondary MSU experienced a similar anomaly temporarily halting science acquisitions. On May 15, 2019, a new data acquisition approach was implemented and science acquisitions resumed. To optimize the new acquisition approach TIR bands 2, 4 and 5 are being downloaded. The data products are as previously, except the bands not downloaded contain fill values (L1 radiance and L2 emissivity).

  • Data acquisition gap: From February 8 to February 16, 2020 an ECOSTRESS instrument issue resulted in a data anomaly that created striping in band 4 (10.5 micron). These data products have been reprocessed and are available for download. No ECOSTRESS data were acquired on February 17, 2020 due to the instrument being in SAFEHOLD. Data acquired following the anomaly have not been affected.

About the image

ECOSTRESS evaporative stress index daily data from ECO4ESIALEXIU product over Iowa, United States, acquired on March 23, 2018.

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User Guide

Algorithm Theoretical Basis Document (ATBD)

Product Specification Document (PSD)

Earthdata Search Quick Guide

Using the Data

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