It is proved in this paper that NWP systematic forecast errors in the zonal mean circulation are due to the difference in westerly acceleration process during the forecasting period between model and real atmospheres....It is proved in this paper that NWP systematic forecast errors in the zonal mean circulation are due to the difference in westerly acceleration process during the forecasting period between model and real atmospheres. Those forcing factors which evoke the zonal mean wind variation can be split into various linear terms according to the non-acceleration theorem in a primitive equation system,By applying this tech- nique to the diagnosis of the forecast produets of the T42L9 model in January 1992 and in July 1992, it is indicated that the model has the ability to forecast the zonal mean wind to a reasonable extent, but there are still some errors in several places,especially in the upper troposphere and lower strato- sphere in the mid-latitude region as well as near the surface.The results of analysis by employing this scheme reveal the reason responsible for the systematic forecast errors of the zonal mean wind in the model and the possible way of improving it. It is also shown that non-acceleration theorem can be used as an efficient tool to diagnose the physical processes of NWP models.展开更多
The distribution of monthly mean error of NMC model forecasts and its seasonal variation are investi- gated.The ratio of monthly mean error to standard deviation is used here to find out that the region where a correc...The distribution of monthly mean error of NMC model forecasts and its seasonal variation are investi- gated.The ratio of monthly mean error to standard deviation is used here to find out that the region where a correction of systematic error is needed and appropriate is mainly in low latitudes.The improvement,after the model's vertical resolution and some physical parameters were changed from April 1985,is investigated,and the NMC operational model forecasts have also compared with those of ECMWF.展开更多
文摘It is proved in this paper that NWP systematic forecast errors in the zonal mean circulation are due to the difference in westerly acceleration process during the forecasting period between model and real atmospheres. Those forcing factors which evoke the zonal mean wind variation can be split into various linear terms according to the non-acceleration theorem in a primitive equation system,By applying this tech- nique to the diagnosis of the forecast produets of the T42L9 model in January 1992 and in July 1992, it is indicated that the model has the ability to forecast the zonal mean wind to a reasonable extent, but there are still some errors in several places,especially in the upper troposphere and lower strato- sphere in the mid-latitude region as well as near the surface.The results of analysis by employing this scheme reveal the reason responsible for the systematic forecast errors of the zonal mean wind in the model and the possible way of improving it. It is also shown that non-acceleration theorem can be used as an efficient tool to diagnose the physical processes of NWP models.
文摘The distribution of monthly mean error of NMC model forecasts and its seasonal variation are investi- gated.The ratio of monthly mean error to standard deviation is used here to find out that the region where a correction of systematic error is needed and appropriate is mainly in low latitudes.The improvement,after the model's vertical resolution and some physical parameters were changed from April 1985,is investigated,and the NMC operational model forecasts have also compared with those of ECMWF.
