亚非副热带西风急流入口区位置及动能异常对中国华北盛夏年代际干旱的影响

研究使用了欧洲中期天气预报中心(ECMWF)提供的全球再分析数据,通过局地多尺度能量涡度分析法(MS-EVA)研究7-8月亚非急流入口区域的位置及能量变化对华北地区干旱的影响.结果发现:7月亚非急流入口区域在1997年之后有明显的北抬趋势,使得北大西洋及欧洲辐射的能量更易进入急流;8月亚非急流入口区域在1997年后有东...

Influence of the Position and Kinetic Energy Anomalies of the Inlet Region of the Asian-African Subtropical Westerly Jet on the Mid-Summer Interdecadal Drought in North China

The drought in North China in midsummer showed an interdecadal increase. This paper used global reanalysis data provided by the European Center for Medium-Term Weather Forecast(ECMWF)and the local multi-scale energy vorticity analysis method(MS-EVA)to study the effect of the location and energy change of the Asian-African jet stream entrance area in July and August on the drought in North China. The results show that:In July,the entrance area of the Asian-African jet stream had a clear northward trend after 1997,making it easier for the energy radiated by the North Atlantic and Europe to enter the jet stream;In August,the entrance area of Asian-African jet contracted eastwards after 1997,but the entrance area of jet was full of energy,making it easy for energy to enter the jet. The energy disperses downstream under the action of the waveguide,passes over the North China area,and converges on the west side of the average trough,which is not conducive to the upward movement of the air flow;the divergence is strengthened on the east side of the average trough,so that the trough moves eastward,and the position of North China changes from the front of the trough to the back of the trough. The energy in the jet stream spreads to the coastal areas of China,causing the western Pacific subtropical high to retreat eastward,weakening the water vapor transport to North China,which is not conducive to precipitation in North China.