The Global Distribution of Cirrus Clouds Reflectance Based on MODIS Level-3 Data

Fengmei Zhao,Xin Wu,Congming Dai,Chaoli Tang,Heli Wei

doi:10.3390/atmos11020219

Abstract

Cirrus clouds are crucially important to weather, climate and earth energy balance studies. The distribution of cirrus reflectance with latitude and season is an interesting topic in atmospheric sciences. The monthly mean Level-3 MODIS cirrus reflectance is used to analyze the global distribution of cirrus clouds, which covers a period from 1 March 2000 to 28 February 2018. The latitude, from 90° S to 90° N, is divided into 36 latitude zones with 5° interval. Data in each latitude zone are analyzed. The research results show that the slopes of cirrus reflectance variation in the Northern and Southern Hemisphere are −1.253 × 10−4/year and –1.297 × 10−4/year, respectively. The yearly-average cirrus reflectance reveals strong negative correlation with time in the Northern Hemisphere, i.e., the correlation coefficient is −0.761. Then the statistical analysis of cirrus reflectance is performed in different seasons, the results show that cirrus reflectance varies obviously with seasonal change. Additionally, for the [30°, 90°] latitude regions, cirrus reflectance reaches the minimum in summer and the maximum in winter in the Southern and Northern Hemisphere.

Highlights

Cirrus clouds are composed of various sizes and shapes of non-spherical ice crystal particles, distributed in a height range of 5–20 km
This paper mainly focuses on the statistical analysis of cirrus reflectance, based on the version 6 (V6) MODerate Resolution Imaging Spectroradiometer (MODIS) Level-3 monthly products from
The cirrus reflectance can be used to calculate the attenuated solar radiation reflected by thin cirrus clouds, so the study distribution of cirrus reflectance has great impacts on improving

Summary

Introduction

Cirrus clouds are composed of various sizes and shapes of non-spherical ice crystal particles, distributed in a height range of 5–20 km. Cirrus clouds have attracted considerable interest because of their impact on the Earth’s radiation budget and weather changes [1,2,3,4]. Cirrus clouds cool the atmosphere by scattering or reflecting solar radiation that reaches the surface and the atmosphere. Cirrus clouds absorb long-wave radiation emitted from the surface and the atmosphere, heating the atmosphere [5,6]. Their overall effect on earth atmospheric radiative energy budget is not yet fully quantified. The uncertainty of the overall effect arises mainly from the numerous interactions and feedbacks between dynamical, microphysical and radiative processes affecting cirrus clouds, which are poorly understood and poorly constrained by available data [7,8,9,10,11]

Methods

Findings

Discussion

Conclusion