Assessment on Unsystematic Errors of GRAPES_GFS 2.0

Unsystematic error is one of main sources of model simulation error, which is mainly induced by initial field error and model defect. Global and Regional Assimilation and Prediction System(GRAPES) global model forecast data and final analysis data made by National Centers for Environmental Prediction(NCEP)during January, April, July, October in 2014 are chosen to be compared and analyzed. In terms of temporal variation, conclusion could be made that peaks of unsystematic errors in both north and south hemispheres occur in their respective winters, and errors show periodical changes. With the increase of forecasting time, the model unsystematic mean square error along with geopotential height field increases over time, first in an exponential function way, and then linear growth. In addition, linear growth in temperature field and zonal wind field are discovered. It shows in the consequence that the large value of model unsystematic mean square error center in mid-latitude and distribute like zonal banded. Lar