中文摘要：

采用WRF v3模式,利用AMDAR资料与NCEP再分析资料,对2007年发生于南海周边海域的高空越洋航线上,110个中度以上晴空颠簸事例与196个无颠簸事例进行数值模拟。选取布朗指数、水平风切变指数等6个晴空颠簸诊断指数,通过计算各指数的有颠簸诊断准确率、无颠簸诊断准确率、TS评分、ETS评分等指标,研究指数及其阈值的适用性。研究表明：（1）布朗指数是诊断南海周边海域越洋航线上的晴空颠簸的最佳指数,并在取＂3.2×10-5＂为阈值时诊断效果最佳。（2）南海周边海域的越洋航线上的晴空颠簸对于诊断指数阈值的选取十分敏感,在晴空颠簸的数值预报中,在合理选择指数的基础之上,应当认真研究设定指数的阈值。

英文摘要：

Based on WRFV3 model,the Aircraft Meteorological Data Relay（ AMDAR） data and NCEP reanalysis data were used to numerically simulate the 110 moderate or greater Clear Air Turbulence（ CAT） observations and 196 no turbulence observations on transoceanic airlines over the surrounding waters of South China Sea in 2007. The applicability of turbulence indices（ Brown Index,Horizontal Wind Shear Index,MOSCAT Index,Dutton Index,Turbulence Index I,Turbulence Index II） and their corresponding threshold were researched through calculating the probability of detection of ＂yes＂observations,probability of detection of ＂no＂observations,true skill statistic and equitable threat score of the preselected six turbulence indices. Results show that：（ 1） Brown index is the best diagnostic index of CAT on transoceanic airlines over the surrounding waters of South China Sea,especially when its threshold amounts to 3. 2 × 10-5.（ 2） The diagnosis of CAT on transoceanic airlines over the surrounding waters of South China Sea is significantly sensitive to the selection of threshold value.