Evaluation of Cloud Mask and Cloud Top Height from Fengyun-4A with MODIS Cloud Retrievals over the Tibetan Plateau

Wenjing Xu,Daren Lyu

doi:10.3390/rs13081418

Abstract

The Tibetan Plateau (TP) has profound thermal and dynamic influences on the atmospheric circulation, energy, and water cycles of the climate system, which make the clouds over the TP the forefront of atmospheric and climate science. However, the highest altitude and most complex terrain of the TP make the retrieval of cloud properties challenging. In order to understand the performance and limitations of cloud retrievals over the TP derived from the state-of-the-art Advanced Geosynchronous Radiation Imager (AGRI) onboard the new generation of Chinese Geostationary (GEO) meteorological satellites Fengyun-4 (FY-4), a three-month comparison was conducted between FY-4A/AGRI and the Moderate Resolution Imaging Spectroradiometer (MODIS) for both cloud detection and cloud top height (CTH) pixel-level retrievals. For cloud detection, the AGRI and MODIS cloud mask retrievals showed a fractional agreement of 0.93 for cloudy conditions and 0.73 for clear scenes. AGRI tended to miss lower CTH clouds due to the lack of thermal contrast between the clouds and the surface of the TP. For cloud top height retrievals, the comparison showed that on average, AGRI underestimated the CTH relative to MODIS by 1.366 ± 2.235 km, and their differences presented a trend of increasing with height.

Highlights

Clouds cover about 60~70% of the globe [1,2] and exert an enormous influence on weather and climate [3]
The results showed that the two products from Advanced Geosynchronous Radiation Imager (AGRI) and Moderate Resolution Imaging Spectroradiometer (MODIS)
Three months (June, July, and August 2020) of collocated AGRI and MODIS cloud detection and cloud top height (CTH) retrievals over the Tibetan Plateau (TP) area were compared

Summary

Introduction

Clouds cover about 60~70% of the globe [1,2] and exert an enormous influence on weather and climate [3]. They are the prerequisite for precipitation, which are the intermediate stage between water vapor and precipitation. All moist processes in the atmosphere involve clouds, which play an important role in Earth’s water cycle [4,5]. Clouds play an extremely critical role in regulating the radiation budget of the Earth–atmosphere system. Clouds play a fundamental role in our weather and climate, there is much that we do not know. To predict changes in weather and climate brings the subject of clouds back to the forefront of atmospheric science and climate science [5]

Objectives

Results

Discussion

Conclusion