Abstract
In the present study we estimated daily evapotranspiration using GPS and meteorological data obtained at a plain, situated in the northern part of Kyushu Island, Japan. The seasonal variation of GPS-derived precipitable water vapor (GPS-PWV) was revealed at the study area throughout one year. The relation of screen-level air temperature to GPS-PWV was analyzed, and a regression equation was presented between them on the basis of the'saturated water vapor curve'. Evaluating the representative relative humidity at the study area, a formula including humidity was dderived as a function of daily GPS-PWV to calculate vapor pressure near the ground. Daily potential evapotranspiration was estimated during the analyzed period using the calculated vapor pressure. The estimated evapotranspiration agrees fairly well with that inferred by a conventional method. This suggests that GPS could be useful for estimation of daily potential evapotranspiration at local areas.
