Purpose of Review

Long-standing biases in simulations of past and present climate states and climate model disagreement even in sign of future monsoon rainfall changes evince limitations in our theoretical understanding.

Recent Findings

The dominant theoretical paradigms for understanding monsoon rainfall—convective-quasi equilibrium (CQE), the moist static energy (MSE) budget, and monsoons as local Intertropical Convergence Zone (ITCZ) shifts—all jettison the traditional “land-sea breeze” paradigm. Summer monsoon precipitation falls when the assumptions of CQE are most satisfied but those of the ITCZ shift framework are least satisfied. Zonal asymmetries, changes in ITCZ width and strength, hydrology-vegetation-CO₂ coupling, and timescale-dependent responses complicate inferences of monsoon rainfall from paleoclimate proxy records. The MSE budget framework applied to deliberately designed simulations can illuminate key mechanisms underlying monsoon responses to external forcings, presenting a path toward falsifying model projections.

Summary

Sustained, rapid progress in monsoon rainfall theory is urgently needed by society and is plausible based on recent advances.

中文翻译：

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过去和未来季风降雨变化的理论

审查目的

在过去和现在的气候状态模拟中长期存在的偏见以及气候模型的分歧，即使未来季风降雨变化的迹象也表明我们的理论理解受到限制。

最近的发现

理解季风降雨的主要理论范式-对流-准平衡（CQE），湿静能量（MSE）预算以及随着当地热带收敛带（ITCZ）的转变而季风-都抛弃了传统的“陆海风”范式。当最满足CQE的假设但最不满足ITCZ转换框架的假设时，夏季季风降水下降。区域不对称性，ITCZ宽度和强度的变化，水文-植被-CO ₂耦合以及时间尺度相关的响应使根据古气候代用记录推断季风降雨变得复杂。适用于精心设计的模拟的MSE预算框架可以阐明季风对外部强迫的响应背后的关键机制，为伪造模型预测提供了一条途径。

概要

社会迫切需要季风降雨理论的持续，快速发展，并且根据最近的进展是合理的。