基于Ｔ／２分数间隔的ＳＥＩ双模式盲均衡算法

采用NCEP/NCAR 1°×1°最后分析资料（final analysis,FNL）计算“圣帕”台风螺旋度,探讨各垂直层上水平螺旋度与强降水时间演变的关系、水平螺旋度与强降水落区的关系以及垂直螺旋度时间演变与强降水发生、发展的关系。结果表明,700 hPa螺旋度最能反映强降水时间演变,正螺旋度大值中心附近与暴雨落区一致,同区域内螺旋度中心值的强弱与该区域内降水的强弱关系密切;若垂直方向上高低层的螺旋度同时由负值转为正值,则强降水发生,反之降水减弱、停止;对于预报台风强降水时效,水平螺旋度远比垂直螺旋度、散度、垂直速度具有更多有效预报时间;对于预报台风强降水落区,垂直螺旋度比水平螺旋度更具有优势,若能利用垂直螺旋度对水平螺旋度预报强降水作出订正可能将有助于提高台风强降水预报准确率。

Perfect Helicity Analysis of Storm Rainfall Course Induced by Typhoon Sepat(0709)

Based on NCEP/NCAR 1 ° × 1 ° final analysis （FNL） data, we calculated the helicity of Typhoon Sepat, and analyzed the relations between the horizontal helicity at different vertical height levels and the temporal variation of storm rainfall, between the horizontal helicity and the location of storm rainfall, and between the temporal variation of vertical helicity with occurring and development of the strong storm rainfall. Results show that the 700 hPa helicity has a strongest power to portray the evolution of strong storm rainfall;the location of big positive helicity center and its neighborhood is consistent with the falling area of storm rainfall ; the central strength of helicity in a region has a close relation with the rainfall strength there ; if the horizontal helicity at high-and low-levels all changes from negative to positive,the storm rainfall will happen, and v. v. ;using of horizontal helicity has more predictable time than that of vertical helicity, divergence or vertical velocity for the prediction of typhoon storm rainfall ; using of vertical helicity has more advantages than that of horizontal helicity for the precipitation intensities variation of typhoon storm rainfall;if the vertical helicity is used to correct the typhoon storm rainfall predicted by horizontal helicity, it will help to improve the prediction accuracy rate of typhoon storm rainfall.