Analyzing the Probability of Acquiring Cloud-Free Imagery in China with AVHRR Cloud Mask Data

Abstract

Optical remote sensing data are used widely in many fields (such as agriculture, resource management and the environment), especially for the vast territory of China; however, the application of these data is usually limited by clouds. Although it is valuable to analyze the probability of acquiring cloud-free imagery (PACI), PACI using different sensors at the pixel level across China has not been reported. In this study, the PACI of China was calculated with daily Advanced Very High Resolution Radiometer (AVHRR) cloud mask data from 1990 to 2019. The results showed that (1) PACI varies dramatically in different regions and months in China. The value was larger in autumn and winter, and the largest figure reached 49.55% in October in Inner Mongolia (NM). In contrast, relatively small values occurred in summer, and the minimum value (5.26%) occurred in June in South China (SC). (2) As the climate changes, the PACI has increased significantly throughout the country and most regions, especially in North China (NC), with a growth rate of 1.9% per decade. The results can be used as a reference for selecting appropriate optical sensors and observation times in areas of interest.

An Improved Fmask Method for Cloud Detection in GF-6 WFV Based on Spectral-Contextual Information

“…However, the extraction of feature information in remote sensing images is disturbed by clouds to varying degrees due to the influence of climate and the sensitivity of the visible bands and NIR band to clouds [1,2]. GF-6, the first optical remote sensing satellite for precision agricultural observations in China [3,4], is not capable of penetrating clouds and fog [5]. Clouds will hinder the radiation transmission between the sensor and the ground objects [6].…”