Location: Soil and Water Management ResearchTitle: Evaluating the operational simplified surface energy balance (SSEBop) approach for ET Mapping with Landsat data using lysimetric observations in the semi-arid Texas High Plains Author
|Senay, Gabriel - Us Geological Survey (USGS)|
|Bohms, Stephanie - Us Geological Survey (USGS)|
|Howell, Terry - Retired ARS Employee|
|Friedrichs, M - Us Geological Survey (USGS)|
|Marek, Thomas - Agrilife Research|
|Verdin, Thomas - Us Geological Survey (USGS)|
Submitted to: Hydrology and Earth System Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2013
Publication Date: 1/15/2014
Citation: Senay, G., Gowda, P.H., Bohms, S., Howell, T.A., Friedrichs, M., Marek, T., Verdin, T. 2014. Evaluating the operational simplified surface energy balance (SSEBop) approach for ET Mapping with Landsat data using lysimetric observations in the semi-arid Texas High Plains. Hydrology and Earth System Sciences. 11:723-756. doi:10.5194/hessd-11-723-2014.
DOI: https://doi.org/10.5194/hessd-11-723-2014 Interpretive Summary: Evapotranspiration (ET) maps for large irrigated regions are essential for developing and evaluating irrigation management strategies. The operational Simplified Surface Energy Balance (SSEBop) approach was developed for this purpose. However, the SSEBop is not evaluated for its ability to derive ET fluxes from Landsat datasets. In this study, the performance of the SSEBop for estimating daily and seasonal ET was evaluated with lysimeter-measured crop ET under dryland and irrigation management practices. Results demonstrated that the SSEBop can produce quick and reliable ET maps that can be used for managing water resources at regional scales.
Technical Abstract: The operational Simplified Surface Energy Balance (SSEBop) approach was applied on 14 Landsat 5 thermal infrared images for mapping daily actual evapotranspiration (ETa) fluxes during the summer season (March-October) in 2006 and 2007. Data from four large lysimeters, managed by the USDA-ARS Conservation and Production Research Laboratory were used for evaluating the SSEBop estimated ETa. Lysimeter fields are arranged in a 2 x 2 block pattern with two fields each managed under irrigated and dryland cropping systems. The modeled and observed daily ETa values were grouped as "irrigated" and "dryland" at four different aggregation periods (1-day, 2-day, 3-day and “seasonal”) for evaluation. There was a strong linear relationship between observed and modeled ETa with R2 29 values ranging from 0.87 to 0.97. The root mean square error (RMSE), as percent of their respective mean values, were reduced progressively with 28%, 24%, 16% and 12% at 1-day, 2-day, 3-day, and seasonal aggregation periods, respectively. With a further correction of the underestimation bias (-11%), the seasonal RMSE reduced from 12 to 6%. The random error contribution to the total error was reduced from 86 to 20% while the bias' contribution increased from 14 to 80% when aggregated from daily to seasonal scale, respectively. This study shows the reliable performance of the SSEBop approach on the Landsat data stream with a transferable approach for use with the recently launched LDCM (Landsat Data Continuity Mission) Thermal InfraRed Sensor (TIRS) data. Thus, SSEBop can produce quick, reliable and useful ET estimations at various time scales with higher seasonal accuracy for use in regional water management decisions.