Thermal Remote Sensing of Drought and Evapotranspiration

Authors: Anderson, Martha; Kustas, William - Bill

Submitted to: Trans American Geophysical Union
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2008
Publication Date: 6/24/2008
Citation: Anderson, M.C., Kustas, W.P. 2008. Thermal remote sensing of drought and evapotranspiration. EOS Transactions, American Geophysical Union. 89(26):233-234.

Interpretive Summary: Water lost to the atmosphere through evapotranspiration (ET: soil evaporation + canopy transpiration) serves to cool the Earth’s surface. Just as a thermometer is used to diagnose stress in the human body, land-surface temperature (LST) derived from remote-sensing data in the thermal-infrared (TIR) band (8-14 'm) is a valuable diagnostic of biospheric stress resulting from soil moisture deficiencies. In land-surface modeling, TIR imagery can serve as an effective substitute for precipitation data, providing much-needed water information in data-poor regions of the world. Of particular utility are TIR data at “high” spatial resolution (defined here as approximately 100 m or finer), resolving natural and anthropogenic land-cover features important to local and regional water management: individual fields and irrigation pivots, canals and riverbeds, reservoirs, and other man-made hydrologic structures. This paper describes applications of multi-scale thermal remote sensing data in water resource and drought monitoring applications, and discusses the ramifications of the decision by NASA to discontinue the heritage high-resolution TIR imaging capabilities for the next Landsat satellite, the Landsat Data Continuity Mission (LDCM).

Technical Abstract: Across the U.S. there are ever increasing and competing demands for freshwater resources for use in agriculture, ecosystems sustainability and urban development. Recent extended droughts in the Western and Southeastern U.S. have further exacerbated ongoing “water wars”. To facilitate wise water management, and to better identify and mitigate the impacts of drought, there is a critical need for robust, operational assessments of ET and water stress at the field, county, watershed, state and continental scales. Just as a thermometer is used to diagnose stress in the human body, land-surface temperature (LST) derived from thermal remote sensing is a valuable diagnostic of the surface moisture status – dry soil and stressed vegetation both lead to elevated LST. In this article we will discuss methodologies for integrating thermal remote sensing from multiple satellite platforms to diagnose ET, vegetation stress, and soil moisture status at spatiotemporal resolutions relevant to management applications. Landsat is the only unclassified satellite currently operated by any nation that routinely provides global TIR images at spatial resolutions required for water management over agricultural landscapes. The decision by NASA not to continue the heritage TIR imaging capabilities for the next Landsat satellite, the Landsat Data Continuity Mission (LDCM), jeopardizes well-developed water management programs employing high-resolution thermal remote sensing in the western U.S. and other water-limited parts of the globe. The Hyperspectral Infrared Imager (HyspIRI) mission recommended by the National Research Council (NRC) would significantly help to address this impending TIR data gap.