The southern Tibetan Plateau (TP) is snow covered during cold season but exhibits faster snow melting in early summer. Using in situ observations and improved satellite-derived data, the present study indicates that the snow depth (SD) over the southern TP exhibits distinction characteristics between late spring (i.e., P1: April 16th–May 15th) and early summer (i.e., P2: May 16th–June 14th). In terms of climate states, the snow melting rate over the southern TP in P2 is faster than that in P1. The acceleration of snow melting during P2 is mainly found over high elevation areas caused by the increase of local air temperature. Diagnoses of the thermodynamic equation further demonstrate that the warming over the southern TP during the two periods is mainly attributed to the meridional temperature advection and diabatic heating in situ. On the interannual time scale, the SD over the southern TP is closely related to diabatic heating over South Asia. During P1, the diabatic cooling from the southern Bay of Bengal eastward to the western South China Sea suppresses convection over the Bay of Bengal and southern TP and has resulted in an upper-level anomalous cyclone and cold temperature anomalies from the surface to 200 hPa over the southern TP, favoring the above-normal SD over the southern TP. On the other hand, SD over the southern TP in P2 is closely related to diabatic cooling over the northern Indochina Peninsula and diabatic heating over the southern China. But we could not prove that these diabatic heating anomalies can affect the SD over the southern TP by modulating local surface air temperature. This may be limited by the quality of the data and the simulation capability of the simple model.

中文翻译：

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春末夏初南亚非绝热加热与青藏高原南部积雪深度的年际关系：气温的作用

青藏高原南部 (TP) 在寒冷季节被积雪覆盖，但在初夏融雪速度更快。利用原位观测和改进的卫星数据，本研究表明，高原南部的积雪深度 (SD) 表现出晚春（即 P1：4 月 16 日至 5 月 15 日）和初夏（即 P2 ：5 月 16 日至 6 月 14 日）。从气候状态看，P2高原南部融雪速度快于P1。P2期间积雪加速融化主要表现为局部气温升高导致的高海拔地区。热力学方程的诊断进一步表明，两期高原南部增暖主要归因于经向温度平流和原地非绝热加热。在年际时间尺度上，高原南部的SD与南亚非绝热加热密切相关。P1期间，从孟加拉湾南部向东到南海西部的非绝热冷却抑制了孟加拉湾和高原南部的对流，导致了上层异常气旋和从地表到200 hPa的冷温异常青藏高原南部，有利于青藏高原南部高于正常水平的标准差。另一方面，P2高原南部的SD与中南半岛北部的非绝热降温和华南的非绝热加热密切相关。但我们无法证明这些非绝热加热异常可以通过调节当地地表气温来影响高原南部的SD。