谱逼近方法对台风Megi(2010)路径模拟的改进及影响分析

将谱逼近方法应用到台风Megi(2010)数值模拟试验中，通过选择不同物理量配置，分析得到影响台风Megi路径变化的关键环境场因子，并在此基础上分析关键因子不同高度范围和不同尺度信息对台风路径变化的影响。结果表明，采用谱逼近方法能够有效降低整个模拟时段，尤其是路径北折阶段台风路径模拟偏差，其中天气尺度环境风场是影响台风路径变化的关键因子。在过岛阶段，谱逼近850 hPa以上的中低层环境风场造成模拟路径偏差增大，但是改善了台风路径北折阶段的路径模拟结果；此外500~1 000 km尺度的中尺度环境风场对Megi转折以及转折后的移速移向具有重要影响，也减小了过岛阶段路径偏差的增长程度。通过分析各试验对主要天气系统、引导气流以及台风内部结构的模拟结果表明，谱逼近环境风场能够改善模式对中低纬环流系统的模拟，有利于更为准确地得到路径转折阶段的引导气流；同时谱逼近环境风场后会影响台风内部结构，对台风路径模拟的移速移向造成影响。 

THE IMPROVEMENTS AND INFLUENCES OF THE SPECTRAL NUDGING TECHNIQUE ON THE TRACK SIMULATION OF TYPHOON MEGI(2010)

Spectral nudging(SN) technique is applied to the numerical simulation of Typhoon Megi(2010). By choosing different physical variables in sensitivity tests, a key environmental factor to the track simulation as well as the impact of this key factor within different vertical height ranges and at different scales are analyzed. It indicates that the outputs with the SN can effectively reduce the track error of Megi(2010), especially in its deflection period. The synoptic-scale environmental wind field is the key factor influencing the typhoon track and its change. Although nudging the lower-tropospheric wind component above 850hPa increases the track error during the landfall period, it plays an important role in improving the track simulation during the deflection period. In addition, nudging a meso-scale environmental wind field of 500~1000km can sharply reduce the track error in the deflection process and relieve the error increase during the landfall period. Analyzing the main background systems, steering flow and inner structure of the typhoon itself shows that nudging the environmental wind field can improve the simulation of mid- and low-latitude systems and acquire more accurate steering flows. Then the tests with the SN also influence the inner structure of the typhoon itself and affect the movement of the typhoon.