Diurnal corrections of short-term surface temperature forecasts using the Kalman filter

Abstract

Deviations between temperature forecasts and observations were studied at several locations in Norway. It was found that the sign and magnitude of the deviations varied considerably in both time and space. Moreover, the diurnal variation of the systematic errors increased as the diurnal variation between daytime and nighttime increased. A Kalman filter model has been constructed that allows for diurnally varying corrections. The results of the correction procedure have been verified for about one-half of them. The correction procedure reduced the monthly bias of the forecasts at each observing station to values close to zero. The monthly standard deviations of the differences between forecasts and observations remained essentially unchanged. They were slightly reduced in summertime but could be slightly increased in wintertime for the long-term forecasts.