Short-term Complex Forecasting of Geopotential Height and Temperature. Postprocessing of Hydrodynamic Models

A method for joint statistical processing of the forecast fields of geopotential height and temperature over the Northern Hemisphere with a lead time up to 72 hours is described. These forecast fields were obtained from several operational hydrodynamic models. The approach reduces essentially the forecast errors for both meteorological fields for all lead times at standard pressure levels in the troposphere and lower stratosphere as compared to the best hydrodynamic schemes. Along with statistical methods, the variational adjustment of the vertical profiles of geopotential height and temperature is applied and reduces the forecast error when using the approximation of the profiles by cubic splines. The temperature forecast error increases approximately linearly with lead time, and the geopotential height error grows quadratically.