Location: Soil and Water Management ResearchTitle: Accuracy assessment of NOAA's daily reference evapotranspiration maps for the Texas High Plains Author
|Moorhead, Jerry - Jed|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2014
Publication Date: 4/7/2014
Citation: Moorhead, J.E., Gowda, P., Paul, G., Hobbins, M.T., Senay, G.B., Marek, T.H., Porter, D.O. 2014. Accuracy assessment of NOAA's daily reference evapotranspiration maps for the Texas High Plains [abstract]. ASABE Paper No. 1873929. Interpretive Summary:
Technical Abstract: The National Oceanic and Atmospheric Administration (NOAA) provides daily reference ET for the continental U.S. using climatic data from North American Land Data Assimilation System (NLDAS). This data provides large scale spatial representation for reference ET, which is essential for regional scale water resources management applications. However, climatic datasets used in the estimation of reference ET are measured over surfaces that are different from short (grass) or tall (alfalfa) reference crops. The error associated with this discrepancy is largely unknown. In this study, NOAA-NLDAS daily alfalfa (tall crop) reference ET maps were evaluated for accuracy using reference ET data from the Texas High Plains Evapotranspiration (TXHPET) network, which operates 18 reference ET weather stations throughout the Texas High Plains for irrigation scheduling and groundwater management purposes. Daily alfalfa reference ET and the climatic data (air temperature, wind speed, and solar radiation) used for calculating reference ET were extracted from the NOAA-NLDAS maps for TXHPET locations and compared against ground measurements on a reference crop. Results indicated that reference ET from the NOAA-NLDAS dataset slightly overestimated TXHPET data with RMSEs ranging from 31.9%-46.6% of the mean daily reference ET from the TXHPET network. The R2 values ranged from 0.76 - 0.82. The over estimation of TXHPET's reference ET by the NOAA-NLDAS data can be partly attributed to the use of higher air temperature and wind speed measurements observed on non-standard surfaces (e.g. airport) in the NOAA-NLDAS dataset. Therefore, a correction factor may be needed to revise NOAA-NLDAS reference ET maps before using it for regional water management and irrigation scheduling applications.