Is Radiative Convective Equilibrium Applicable over the Tibetan Plateau?

Radiative convective equilibrium (RCE) critically constrains tropical climates but its applicability to elevated terrains like the Tibetan Plateau (TP) remains unknown. Based on 23 years (2001-2023) of multiple observational datasets, our study provides the first comprehensive observational assessment of RCE applicability over the TP. We find that the TP exhibits a pronounced annual-mean energy imbalance of -15.9 W/m² and this state is characterized by strong seasonal asymmetry. Summers show intense positive energy imbalance of +56.0 W/m² that is driven by latent heating from precipitation while winters show extreme radiative cooling of -71.8 W/m². Transitional months including April and September alone achieve transient energy balance across the entire plateau region. The TP manifests four energy imbalance regimes that are categorized by specific precipitation intensity and radiative cooling thresholds. These regimes transition seasonally with Strong Precipitation-Weak Cooling dominating the summer monsoonal regions of the TP and Weak Precipitation-Strong Cooling prevailing in the winter and autumn periods of the plateau. Daily near-RCE conditions occur transiently with only 5–10% frequency across all spatiotemporal scales and this feature contrasts sharply with tropical regions where equilibrium naturally emerges through spatial aggregation. Analysis of extreme events reveals that intense latent heating drives positive imbalance during summer heating events and this imbalance is compensated primarily by enhanced vertical dry static energy divergence. Persistent radiative cooling creates sustained negative imbalance during winter cooling events and this deficit is countered by vertical divergence of dry static energy flux and meridional cold air advection. These results challenge the direct application of tropical RCE paradigms to TP region and they highlight the need for a skewed RCE framework that explicitly incorporates the TP’s unique thermal forcing effects shaped by its elevated terrain and distinct atmospheric processes.
辐射对流平衡（RCE）对热带气候造成了关键限制，但其在青藏高原（TP）等高原地区的适用性尚不清楚。基于 23 年（2001-2023 年）的多重观测数据集，本研究首次对 RCE 在 TP 上的适用性进行了全面观察评估。我们发现 TP 表现出明显的年均能量失衡，达到-15.9 W/m²，该状态表现为强烈的季节不对称。夏季显示出强烈的正能量失衡，达到+56.0 瓦/平方米，由降水潜在加热驱动;冬季则极端辐射冷却，达到-71.8 瓦/平方米。仅包括四月和九月在内的过渡月份，就实现了整个高原地区的瞬态能量平衡。TP 表现出四种能量不平衡状态，按具体降水强度和辐射冷却阈值进行分类。这些模式随季节性转变，夏季季风区域为强降水-弱降温，高原的冬秋季为弱降水-强降水。每日接近 RCE 的条件在所有时空尺度中以短暂的频率出现，仅有 5–10%，这一特征与热带地区通过空间聚合自然形成平衡形成鲜明对比。对极端事件的分析显示，强烈的潜热在夏季供暖事件中驱动正向失衡，而这种失衡主要由增强的垂直干静能散度来补偿。持续辐射冷却在冬季冷却事件中造成持续的负平衡，这一缺口静能通量和子午线冷空气平流的垂直发散所抵消。 这些结果挑战了将热带 RCE 范式直接应用于 TP 区域的观点，并凸显了需要一个倾斜的 RCE 框架，明确纳入 TP 独特热力效应，这些效应由其高地地形和独特的大气过程塑造。