Effects of Cloud Microphysics on the Vertical Structures of Cloud Radiative Effects over the Tibetan Plateau and the Arctic

Yafei Yan,Xiaolin Liu,Xiaocong Wang,Yimin Liu

doi:10.3390/rs13142651

Abstract

The Tibetan Plateau (TP) and the Arctic are both cold, fragile, and sensitive to global warming. However, they have very different cloud radiative effects (CRE) and influences on the climate system. In this study, the effects of cloud microphysics on the vertical structures of CRE over the two regions are analyzed and compared by using CloudSat/CALIPSO satellite data and the Rapid Radiative Transfer Model. Results show there is a greater amount of cloud water particles with larger sizes over the TP than over the Arctic, and the supercooled water is found to be more prone to exist over the former than the latter, making shortwave and longwave CRE, as well as the net CRE, much stronger over the TP. Further investigations indicate that the vertical structures of CRE at high altitudes are primarily dominated by cloud ice water, while those at low altitudes are dominated by cloud liquid and mixed-phase water. The liquid and mixed-phase water results in a strong shallow heating (cooling) layer above the cooling (heating) layer in the shortwave (longwave) CRE profiles, respectively.

Highlights

Clouds have a crucial effect on the radiation budget of the Earth via the reflection of shortwave (SW) and absorption of longwave (LW) radiation by both ice and liquid water particles in clouds [1,2]. The balance of these SW and LW effects is referred to as cloud radiative effects (CRE), with positive values indicating that clouds warm the surface/atmosphere/Earth relative to clear sky conditions and negative values indicating that clouds cool the surface/atmosphere/Earth
We aim to reveal the comparative vertical structures of CRE and related cloud microphysical characteristics over the Tibetan Plateau (TP) and the Arctic based on CloudSat/CALIPSO products
More plentiful cloud water particles with larger sizes and more supercooled water in the liquid phase were found over the TP than over the Arctic

Summary

Introduction

Clouds have a crucial effect on the radiation budget of the Earth via the reflection of shortwave (SW) and absorption of longwave (LW) radiation by both ice and liquid water particles in clouds [1,2]. The balance of these SW and LW effects is referred to as cloud radiative effects (CRE), with positive values indicating that clouds warm the surface/atmosphere/Earth relative to clear sky conditions and negative values indicating that clouds cool the surface/atmosphere/Earth. Due to the lack of knowledge concerning cloud vertical structures and their microphysical processes, clouds remain one of the largest sources of uncertainty in climate model simulations [5,6,7] and the precise modeling of cloud–radiation interactions remains uncertain.

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