Impacts of digital filter initialization on the WRF in the Korea Meteorological Administration

Imbalance between the wind and mass in the initial field can be introduced by objective analyses like 3D-Var or by simple interpolations. The noise could cause spurious precipitation, lead to numerical instabilities, degrade the forecast, and damage the subsequent data assimilation through noisy first-guesses. The digital filter initialization (DFI) is one of the methods to remove the imbalance and to reduce the spin-up problem. The KMA (Korea Meteorological Administration) has developed KWRF (KMA Weather Research and Forecasting) system based on the WRF model and 3DVAR since January 2006 as a trial operational version. But there is no technique for initialization. This paper overviews the effect of DFI on KWRF, with ongoing tuning activities. The forecast results with the 10km KMA operational configuration indicate a satisfying noise reduction and a reasonable spin-up reduction.