南支槽是冬半年位于青藏高原南侧的半永久性低压槽，对中国冬春季降水有重要影响。为了定量评估南支槽的活动特征，研究者提出了很多不同的南支槽指数定义方法。不同南支槽定义具有较大的差异，资料来源和等压面的选择对南支槽指数影响不大，差异主要来源于定义南支槽的物理量不同（位势高度、相对涡度和垂直速度场）。其中，以平均位势高度为基础的南支槽指数受到了全球变暖导致的等压面抬升的强烈影响，它反映的南支槽近几十年的显著减弱是全球变暖的表现，因此需要经过纬向差异校正才能正确反映南支槽的活动和年际年代际变化特征。校正后的南支槽指数表现了南支槽对中国南部地区冬季降水的强烈影响，并反映了自20世纪50年代以来冬季降水与南支槽活动一致的年代际变化特征。

The India-Burma Trough（IBT），a semi-permanent low-pressure system situated on the southern flank of the Qinghai-Xizang（Tibetan）Plateau during the winter half-year，plays a crucial role in modulating winter and spring precipitation patterns across China. To quantitatively characterize IBT activity，researchers have proposed multiple indices from diverse methodological perspectives. While data source selection and isobaric surface choices exert limited influences，the principal distinctions among these indices stem from their utilization of different atmospheric variables，notably geopotential height，relative vorticity，and vertical velocity fields. The regionally mean geopotential height index of the IBT is particularly susceptible to the isobaric surface uplift caused by global warming. Its persistent weakening trend essentially reflects the increasing geopotential height of tropospheric isobaric surface under global warming. Consequently，this necessitates the implementation of zonal correction procedures to accurately capture the trough’s activity charcteristics and its interannual-todecadal variability. The revised index demonstrates interannual and decadal variation patterns comparable to those derived from relative vorticity and vertical velocity，while effectively mitigating the confounding effects of climate warming on geopotential height fields. It reveals a robust correlation between IBT intensity and winter precipitation in South China，with coherent decadal-scale fluctuations observed in both parameters. This revised geopotential height-based index achieves dual objectives：（1）Effectively eliminating global warming-induced isobaric surface uplift artifacts，and（2）Maintaining clear physical interpretability by capturing the localized geo‐ potential height depression characteristic of meridionally elongated trough systems like the IBT. Notably，while detrending methods can reduce climate changes impacts on geopotential height indices，they may inadvertently introduce spurious weakening trends in interannual variability due to discrepancies between short-term atmospheric fluctuations and long-term climate trajectories. This study highlights a critical implication that the validity of regional mean geopotential height as a climate system metric requires rigorous verification. And the isobaric surface rising effects by global warming must be explicitly accounted for to distinguish genuine climate system characteristics from warming-induced artifacts.