Topographic Distance Functions for Interpolation of Meteorological Data

In agriculture and water resource management an important meteorological quantity is the reference evapotranspiration ET0. It is usually estimated from other meteorological quantities measured at weather stations. To estimate ET0 at an arbitrary geographical position these quantities have to be interpolated. The Center for Spatial Technologies And Remote Sensing (CSTARS) at UC Davis uses the DayMet approach for this task. We discuss some inconsistencies within the DayMet approach and suggest improvements. One of the problems of DayMet is the lack of consideration of terrain topography. We define new distance functions that are elevation-dependent and show preliminary results of the comparison of the classic and the improved DayMet approach.