ABSTRACT

Previous studies indicate that the “spring flood” precipitation in northwestern Yunnan is closely related to the movement of the South Asian High (SAH) and the apparent moisture sink (Q₂) in the southeastern Tibetan Plateau (TP). In this study, using 38 years of ERA-Interim daily- and monthly-mean grid data along with 35 years of Gongshan daily precipitation data, the correlation between the movement of the SAH and Q₂ in the southeastern TP was analyzed. Then the Q₂ index (QI) of the SAH movement was constructed, and its impact on the activities of the SAH was analyzed. The results show that the QI affects the vertical transport of latent heat by interfering with the “chimney” effect, which in turn affects the atmospheric vertical motion in the southeastern TP and adjacent areas. This affects the upper 100 hPa wind field, resulting in changes in wind speed and direction in the upper air, the distribution of the geopotential height field, and the intensity and position of the SAH centre. The QI is positively and negatively correlated with the longitude and latitude of the SAH centre, respectively, and positively correlated with the intensity, implying a predictive effect on the movement trend and intensity evolution of the SAH.

摘要

先前的研究表明，云南西北部的“春季洪水”降水与青藏高原东南部（TP）的南亚高压（SAH）的运动和表观水分汇（Q ₂）密切相关。在这项研究中，使用38年的ERA-Interim每日和每月平均网格数据以及35年的贡山日降水数据，分析了东南部TP的SAH和Q ₂之间的相关性。然后Q ₂构造了SAH运动的指数（QI），并分析了其对SAH活动的影响。结果表明，QI通过干扰“烟囱”效应影响潜热的垂直传输，进而影响TP和东南部地区的大气垂直运动。这会影响高100 hPa的风场，从而导致高空的风速和风向，地势高度场的分布以及SAH中心的强度和位置发生变化。QI分别与SAH中心的经度和纬度呈正相关和负相关，与强度呈正相关，这意味着对SAH的运动趋势和强度演变具有预测作用。