新疆地区夏季平流层低层风场特征分析及数值模拟

利用2017年6—8月的FNL再分析资料分析了新疆地区夏季平流层低层风场的时空演变特征,开展了平流层低层风场的高分辨率数值模拟和检验。结果表明:新疆地区夏季平流层纬向风随时间的变化存在经向差异,同时准零风层开始和结束的时间也存在经向差异,准零风层开始时间南部地区早于北部地区,而准零风层结束时间则相反。整个夏季新疆地区上空的准零风层处于70~40 hPa之间,其高度随时间呈先降低而后升高的变化趋势。准零风层数值模拟结果表明,模拟的准零风层参数与探空资料分析结果相比二者存在一致的变化趋势,准零风层起始高度的平均绝对误差为467 m,该高度对应的风速均方根误差为1.75m/s。

Analysis and Numerical Simulation of Characteristics of Wind Field at Low-level Stratosphere over Xinjiang Region in Summer

The evolution characteristics of the wind field at the low level stratosphere are analyzed based on FNL re analysis data from June to August 2017. After that, high resolution numerical simulations of the wind field at the low level stratosphere are evaluated by sounding data at the Urumqi station. Results show that the temporal transition of the stratosphere zonal wind over the Xinjiang region varied with latitude. Meanwhile, the starting and ending time of the quasi zero wind layer also varied with latitude. Starting time of the quasi zero wind layer was earlier in the southern region than in the northern region. However, it was the opposite of the ending time. In summer, the quasi zero wind layer existed between 70 hPa and 40 hPa over the Xinjiang region. Variation of the quasi zero wind layer altitude presented a trend of declining first and then rising later. Results of the numerical simulation of the quasi zero wind layer showed that the trends of the quasi zero wind layer parameters over time displayed good agreement between simulations and soundings. The mean absolute error of the initial height of the quasi zero wind layer was 467 m. The root mean square error of wind speed at the initial height of the quasi zero wind layer was 1.75 m/s.