CAJ | 학술논문

基于百分位方法,首先通过构建气候等概率区间得到了位势高度场极端天气事件区分方法,并给出了相应的预报结果检验评价方案;以此为基础,对2003年夏季亚欧区域的500hPa位势高度场极端天气事件的NCEP集合概率预报效果进行了深入分析,得到如下结论：1）分析时段和区域内的极端事件的发生频率比气候平均状况略偏高。NCEP集合预报系统对异常偏低的极端事件的预报易偏高,但相对比较可靠;对相对异常偏高极端事件的预报频率随着预报时效的增大而减小,时效小于3d时预报频率偏高,时效大于5d时显著偏低,预报可靠性相对差一些。2）EV（economic value,经济价值）分析表明,NCEP集合预报系统对偏高（低）极端事件的概率预报效果明显高于正常天气事件。3）预报命中率分析表明,在高概率阈值下,预报命中率较低,这与预报系统在部分个例中的不发散有关。随着概率阈值的降低,预报命中率稳步提高,说明集合成员的发散使之可以覆盖实况可能出现的区间,从而得到更好的预报效果。
기우백분위방법,수선통과구건기후등개솔구간득도료위세고도장겁단천기사건구분방법,병급출료상응적예보결과검험평개방안;이차위기출,대2003년하계아구구역적500hPa위세고도장겁단천기사건적NCEP집합개솔예보효과진행료심입분석,득도여하결론：1）분석시단화구역내적겁단사건적발생빈솔비기후평균상황략편고。NCEP집합예보계통대이상편저적겁단사건적예보역편고,단상대비교가고;대상대이상편고겁단사건적예보빈솔수착예보시효적증대이감소,시효소우3d시예보빈솔편고,시효대우5d시현저편저,예보가고성상대차일사。2）EV（economic value,경제개치）분석표명,NCEP집합예보계통대편고（저）겁단사건적개솔예보효과명현고우정상천기사건。3）예보명중솔분석표명,재고개솔역치하,예보명중솔교저,저여예보계통재부분개례중적불발산유관。수착개솔역치적강저,예보명중솔은보제고,설명집합성원적발산사지가이복개실황가능출현적구간,종이득도경호적예보효과。
Based on the percentile method,a distinction method for the extreme weather events is proposed by the construction of the climatologically equally likely intervals firstly.Then,the corresponding forecasting evaluation on extreme weather events is performed for 500 hPa geopotential height over Eurasian area in summer 2003.The results are as follows：1）In the analyzed period and region,the frequency of the extreme events is slightly higher than the climatological average situation.In NCEP-EPS,the forecast frequency is easy to become higher for the lower extreme events,but relatively reliable,whereas it is decreased with the extension of lead-time for the higher extreme events.When the lead-time is less than 3 d （more than 5 d）,the forecast frequency is higher（lower） with relatively less reliability.2）EV（economic value） analysis shows that the performance of NCEP-EPS probabilistic forecast for the higher（lower） extreme events is better than that for the normal weather events.3）Forecast hit rate analysis shows that the hit rate is lower in the high-probability threshold.Further analysis points out that it is perhaps related with the lower ensemble spread in some cases.With the decrease of probability threshold,the hit rate steadily increases.It means that the spread of ensemble members can make them to cover all possible region of observation value,thereby to get the better forecasting results.