XJ-RUCv1.0系统不同边界层方案对地面气象要素预报的影响初探

基于沙漠绿洲戈壁区域同化预报系统（Desert Oasis Gobi Regional Assimilation Forecast System,简称DOGRAFSv1.0）不同边界层方案（YSU,ACM2）对2013年1月和7月的预报结果和实况资料,利用客观检验方法,初步探究不同边界层方案对地面气象要素预报的影响,结果表明：ACM2方案对地面气象要素预报效果总体优于YSU方案,尤其对1月份ACM2方案预报结果优势显著;对于2 m温度,ACM2方案对低温预报偏高的问题有一定改善,但对高温预报偏低的问题有所加重;对于10 m风速,ACM2方案的预报误差明显低于YSU方案;对于降水,ACM2方案在一定程度上改善了1月漏报和空报的问题,但对7月改进不明显,这主要由于ACM2方案在稳定或中性层结下采用的局地闭合算法削弱了边界层顶卷挟和边界层内混合作用,进而抑制了边界层物理过程与对流过程的耦合作用。

The effect of different boundary layer schemes on the forecasting surface meteorological factors of XJ-RUCv1.0

Based on the the forecasts of Xinjiang rapid update cycle of assimilation forecast system (XJ-RUCv1.0) by two PBL schemes (namely YSU and ACM2) and observation data during 2013 January and July, using the objective verification method, the effect of different boundary layer schemes on the forecasting surface meteorological factors is analyzed preliminarily. The results indicate that the performance of the ACM2 scheme takes more advantages than the YSU scheme on the whole, especially in January. As to 2 m temperature, the ACM2 scheme has reduced the bias of forecasting low temperature while magnified the bias of forecasting high temperature. With regard to 10 m wind speed, the forecasting bias of the ACM2 scheme is considerably below the YSU scheme. And for the forecasting precipitation, the ACM2 scheme has reduced the missing rate to some extent in January. This maybe be given rise to the local term under the stable or neural conditions, which contributes to weaken the entrainment of the top of PBL and eddy diffusion of the inner PBL so that the coupled PBL physics and convective process is restrained to a certain degree.