丽江高原湖泊首场透雨分析

Analysis of the First Soaking Rain in the Plateau Lakes of Lijiang

摘要: 通过对丽江两大高原湖泊首场透雨分析发现泸沽湖和程海湖首场透雨出现的日期呈现先偏早后偏晚的趋势，从60年代到90年代中期首场透雨日期出现偏早的趋势，之后一直到2023年首场透雨出现日期是一个呈现偏晚的阶段。首场透雨出现在5月份的频率最高，泸沽湖达63%、程海湖达49%，其次是6月份，仅有1到2场首场透雨出现在7月。首场透雨出现时，高空槽配合切变线的形势占比最高，达45%左右，其次是高原槽配合切变线的形势，为25%左右，另外高空槽配合低层西南气流、高原槽叠加南支槽也会出现透雨天气，但高空有高空槽或高原槽影响且低空无天气系统配合时，泸沽湖会出现透雨天气，但程海湖在该环流形势下不会出现透雨天气。

Abstract: Analysis of the first soaking rain in two plateau lakes of Lijiang reveals that the occurrence dates of the first soaking rain in Luguhu and Chenghai Lake show a trend of first becoming earlier and then later. From the 1960s to the mid-1990s, the first soaking rain tended to occur earlier, but from then until 2023, the trend shifted to later occurrence. The first soaking rain most frequently occurs in May, with Luguhu Lake at 63% and Chenghai Lake at 49%, followed by June. Only 1 to 2 instances of the first soaking rain were recorded in July. When the first soaking rain occurs, the most common synoptic pattern is an upper-level trough combined with a shear line, accounting for about 45% of cases. The second most frequent pattern is a plateau trough with a shear line, making up around 25%. Additionally, soaking rain can also result from an upper-level trough paired with low-level southwesterly airflow or a plateau trough overlapping with a southern branch trough. However, when an upper-level trough or plateau trough is present without any accompanying low-level weather system, Luguhu Lake may still experience soaking rain, whereas Chenghai Lake does not produce soaking rain under such circulation conditions.