中文摘要：

缺乏对流天气发生临近时刻的探空观测资料是制约强对流短时预报水平进一步发展的重要因素。随着数值预报技术水平的持续提高,高时空分辨率数值预报输出的模式探空性能越来越好,这为获取对流发生前的临近探空提供了有益的补充。本文针对北京地区2008年夏季20次较强的对流过程,得出北京市气象局BJ-RUC数值预报系统输出的54511站在分析时次（t=0）和预报时效分别为3和6 h的预报偏差均略差于t=0的分析探空,但是此两个时次的预报探空误差仍然处于可接受的范围内。对比20个对流个例54511站分别基于观测和分析或预报的对流不稳定能量、水平风的垂直切变等基本对流参数可以发现,t=0时次模式分析探空在趋辨和量级上与基于实际探空观测诊断的对流参数均有较好的一致性,基本上能够较为正确地在模式中反映临近对流发生前实际大气的环境特征;但是当考虑实际的预报时效时,t=3和6h的预报探空能够提前约1和4h为预报员提供对未来对流发生潜势预报的判断。因此,此两个时次探空更具有实际的业务应用价值。以两个强对流个例为例分析了BJ-RUC系统提供的分析和预报临近探空的性能及其对强对流潜势预报的指示性作用。结果表明,BJ-RUC输出的分析和预报探空对未来对流发生潜势具有较好的指示作用。但依据模式输出的探空变化要对对流发生时间、强度、落区乃至对流类型进行准确预报仍有一定的难度。

英文摘要：

In this article,the analyzed and forecasted soundings in close proximity to the 20 strong convection incidents occurring in Beijing in summer of 2008 are examined.The soundings at the station No.54511 were obtained from the analyses（t= 0）,and the forecasts（t=3 h and t=6 h）generated by the Beijing Rapid Update Cycle（BJ-RUC）analysis and forecast system. A comparison of the observed soundings and the collocated BJ-RUC soundings in convective environments reveals that the model analyses were reasonably accurate for much of the troposphere.Especially,the bias error of model analyses soundings were basically of the similar magnitudes to the measurement accuracy of the radiosonde observations.The qualities of the 3 h and 6 h forecasted soundings appeared to be worse than the analyses,but still acceptable. Thermodynamic and vertical wind shear parameters derived from the BJ-RUC proximity soundings at the station No.54511 are also evaluated for the 20 summer convection cases in the Beijing area.Trends and magnitudes revealed by the convective parameters of soundings based from the BJ-RUC analyses are quite consistent with the observed results,suggesting that the BJ-RUC analysis sounding can be regarded as a reasonable proxy for observed soundings in convective environments.The forecasted soundings at t=3 hour and t=6 hour are able to provide indications to the forecast of convective potential around 1-and 4-hour ahead of time,respectively,which is valuable especially when considering their implementation in practical operations.Two strong convection cases are given to show the performance and preliminary implementations of the soundings derived from the BJ-RUC analyses and forecasts.From the cases,it can be found that the soundings from the BJ-RUC are helpful to the forecast of future convection potential.But significantly,it＇s still very difficult to accurately forecast the time,strength,location and even the type of convection from the model-output soundings.