Publications

Wang, HF; Xu, N; Fougnie, B; Zhang, P; Bojkov, B; Gu, SY; Shang, J; Chen, L; Hu, XQ; Li, ZQ (2024). Supercooled Water Cloud Detection From Polarized Multi-Angle Imager Data Using 1.37 ?m Water Vapor Polarized Channel. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 129(20), e2024JD041118.

Abstract
Detecting supercooled water clouds (SWCs) is essential for enhancing artificial rainfall, preventing aircraft ice accretion, and developing a better understanding of radiative energy balance. The 1.37 mu m channel, known as strong water vapor absorbing, was made polarized in the polarized multi-angle imager (PMAI) onboard FengYun-3G satellite. The infight data shown that the new 1.37 mu m polarized channel could be used to detect SWCs. The cloudbow is observed around the 140 degrees scattering angle in the 1.37 mu m polarization image, with a maximum polarization reflectance of approximately 0.04-0.06. The indicated water clouds with spherical particles in the high-level altitude could be SWCs. Then, the SWCs detected by 1.37 mu m polarized channel is verified using polarized reflectance of other channels, the reflectance difference of channels, and thermal infrared bright temperature. The presence of cloudbow in 1.03 and 1.64 mu m channels indicate liquid water cloud. The reflectance difference between 1.03 and 1.64 mu m of SWCs agree with characteristic of water cloud. The thermal infrared channels from the imager on the same platform indicate cold cloud with the brightness temperature far below 273.16 K. Therefore, the only use of 1.37 mu m polarized channel could perform the identification of SWCs. PMAI provides a powerful tool for monitoring supercooled water clouds. In this study, cloudbow is observed by the 1.37 mu m polarized channel of PMAI onboard FY-3G satellite. Combination of polarization and water vapor absorbing information, the indicated water clouds with spherical particles in the upper altitude could be identified as SWCs. The identification of SWCs by 1.37 mu m polarization channel is verified by other polarized channels, reflection channels, and thermal infrared channels. Therefore, the 1.37 mu m polarized channel provides a new and fast way to accurately identify SWCs. Further, the SWCs identified by the 1.37 mu m polarized channel could be used to determine the threshold, or be reference of cloud phase identification and verification for traditional methods. Cloudbow is first observed in the 1.37 mu m polarized channel of the polarized multi-angle imager onboard FY-3G satellite The 1.37 mu m polarized channel (1370P) can be used to detect supercooled water clouds The identification of supercooled water clouds by 1370P was verified

DOI:
10.1029/2024JD041118

ISSN:
2169-8996