Responses of Mean and Extreme Precipitation to Different Climate Forcing Under Radiative-Convective Equilibrium

Abstract

Understanding the responses of mean and extreme precipitation to climate change is of great importance. Previous studies have mainly focused on the responses to prescribed sea surface warming or warming due to increases of CO₂. This study uses a cloud-resolving model under the idealization of radiative–convective equilibrium to examine the responses of mean and extreme precipitation to a variety of climate forcings, including changes in prescribed sea surface temperature, CO₂, solar insolation, surface albedo, stratospheric volcanic aerosols, and several tropospheric aerosols. The different responses of mean precipitation are understood by examining the changes in the surface energy budget. It is found that the cancellation between shortwave scattering and longwave radiation leads to a small dependence of the mean precipitation response on forcings. The responses of extreme precipitation are decomposed into three components (thermodynamic, dynamic, and precipitation efficiency). The thermodynamic components for all climate forcings are similar. The dynamic components and the precipitation-efficiency components, which have large spreads among the cases, are negatively correlated, leading to a small dependence of the extreme precipitation response on the forcings.

摘要

了解平均降雨与极端降雨对气候变化的响应是非常重要的. 先前的工作主要集中于其对海平面升温和二氧化碳增加导致的变暖的响应. 本文运用云解析模式研究在辐射对流平衡的理想化条件下, 平均降雨和极端降雨对各种气候强迫(包括海平面温度、 二氧化碳、 太阳辐射、 地表反射率、 平流层火山气溶胶和对流层气溶胶)的响应. 本文通过分析地表能量辐射收支平衡中各项的变化来理解平均降水的不同响应. 短波辐射和长波辐射的变化相互抵消导致平均降雨响应对气候强迫的依赖性弱, 即平均降雨对不同气候强迫所导致的升温的响应差异不大. 极端降水的响应可分为三部分(分别为热力动力学部分、 动力学部分和降雨效率部分). 对各气候强迫引起的降雨变化, 热力动力学部分的贡献量相似, 动力学部分和降雨效率部分的贡献量在不同强迫下变化较大并且呈负相关, 导致极端降雨响应对气候强迫的依赖性弱.