MODIS-Based Potential Evapotranspiration Demand Curves for the Sacramento Soil Moisture Accounting Model

Abstract

A satellite-based potential evapotranspiration (PET) product for streamflow simulations is tested for 15 forecast basins in the Upper Mississippi and Red River watersheds under the forecasting responsibility of the National Weather Service (NWS) North Central River Forecast Center (NCRFC). PET demand curves, which are long-term average estimates of daily PET, are derived using the National Aeronautics and Space Administration’s moderate resolution imaging spectroradiometer sensor (MODIS) on board the Terra and Aqua earth observation satellites. The PET demand curves (referred to as M-PET) are then used as input to the NWS Sacramento soil moisture accounting model (SACSMA) and simulated discharge and evapotranspiration (ET) are evaluated. Simulations using M-PET input are compared to simulations produced using the demand curves of the NCRFC (referred to as NC-PET). The M-PET data correlate better with PET estimated using tower data from three sites located within the study region compared to the NC-PET. The M-PET overall has low positive bias, averaging approximately 0.25 mm day−1 while the NC-PET has larger, negative bias, averaging almost 2 mm day−1. The M-PET discharge simulations have acceptable performance (i.e., Nash Sutcliffe>0.30) for eight of the 15 basins. The simulated ET produced by the M-PET matches the range of observed ET better than the NC-PET when compared to data from the three flux sites. Overall results indicate there is potential for using the M-PET as input into the SACSMA though further work is needed to assess potential data bias.