Location: Soil and Water Management ResearchTitle: Accuracy assessment of NOAA gridded daily reference evapotranspiration for the Texas High Plains
|Hobbins, Michael - National Oceanic & Atmospheric Administration (NOAA)|
|Senay, Gabriel - Us Geological Survey (USGS)|
|Paul, Gearge - Texas Agrilife Research|
|Marek, Thomas - Texas Agrilife Research|
|Porter, Dana - Texas Agrilife Extension|
Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2015
Publication Date: 10/2/2015
Citation: Moorhead, J.E., Gowda, P., Hobbins, M.T., Senay, G.B., Paul, G., Marek, T.H., Porter, D.O. 2015. Accuracy assessment of NOAA gridded daily reference evapotranspiration for the Texas High Plains. Journal of the American Water Resources Association. 51(5):1262-1271. doi: 10.1111/1752-1688.
Interpretive Summary: Accurate daily reference evapotranspiration (ET) is needed for efficient water management from field to regional scales. To meet this need, scientists at NOAA have developed spatially representative daily reference ET maps for the contiguous United States using data from non-agricultural weather networks. These maps are expected to be used as input into various water demand and availability models. In this study, accuracy of the NOAA reference ET maps was evaluated using data from the agriculture-based Texas High Plains ET network. Results showed that the NOAA reference ET values were generally higher than that from the Texas High Plains ET network. Therefore, a bias correction to air temperature and wind speed data used in generating NOAA reference ET or adjustment to the resulting NOAA reference ET may be needed to improve its accuracy.
Technical Abstract: The National Oceanic and Atmospheric Administration (NOAA) provides daily reference evapotranspiration (ETref) maps for the contiguous United States using climatic data from North American Land Data Assimilation System (NLDAS). This data provides large-scale spatial representation of ETref, which is essential for regional scale water resources management. Data used in the development of NOAA daily ETref maps are derived from observations over surfaces that are different from short (grass) or tall (alfalfa) reference crops, often in non-agricultural settings, which carries an unknown discrepancy between assumed and actual conditions. In this study, NOAA daily grass and alfalfa reference ET maps were evaluated for accuracy using observed data from the Texas High Plains Evapotranspiration (TXHPET) network. Daily grass and alfalfa reference ET and the climatic data (air temperature, wind speed, and solar radiation) used for calculating reference ET were extracted from the NOAA maps for TXHPET locations and compared against ground measurements on reference grass surfaces. NOAA reference ET maps generally overestimated the TXHPET observations, which may be attributed to errors in the NLDAS modeled air temperature and wind speed, to which reference ET is most sensitive. Therefore, a bias correction to NLDAS modeled air temperature and wind speed data, or adjustment to the resulting NOAA reference ET, may be needed to improve the accuracy of NOAA reference ET maps.