The utility of climatic station data in making hourly potential evapotranspiration estimates for remote sensing studies

Abstract

Regional estimates of evapotranspiration and soil moisture are often highly inaccurate due to a lack of representative meteorological data with which to calculate the moisture and energy fluxes. A procedure is outlined which uses available hourly climatic station data to estimate these moisture and energy fluxes. These hourly climatic station observations and synthesized radiation were compared to detailed meteorological and radiation flux measurements taken up to 100 km away. The two data sets compared well in both trend and magnitude. Solar and net radiation were modelled by using vapor pressure and observed cloud cover and compared well to values observed at the study sites. Hourly potential evapotranspiration estimates were made with both the micromet measurements and the climatic station data for each region, and also compared well. This study was performed for two areas of different climatic conditions, a natural prairie in Kansas and a bare soil in Beltsville, Maryland. Large-area estimates of hourly potential evapotranspiration made with climatic station data may be useful when combined with additional midday satellite observations in the thermal, visible, and near-infrared bands to estimate relevant vegetation parameters, actual evapotranspiration, and soil moisture.