AIOFM Develops New Cloud Parameter Retrieval Methods for China's Dual-Polarization Payloads DPC and POSP

Recently, a team led by Researcher Chen Cheng at the Optical Remote Sensing Center of the Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, used observation data from two polarization payloads independently developed by the institute and carried on the Gaofen-5 (02) satellite (GF-5 (02)) - the Directional Polarimetric Camera (DPC) and the Polarization Scanning Optical Payload (POSP) - to develop a new method for retrieving cloud optical and microphysical properties. The new method improves the capability of domestically developed spaceborne polarization payloads for fine-scale retrieval of cloud optical and microphysical parameters, and can provide reliable, self-reliant data support for studies of cloud radiative effects and aerosol-cloud interactions.

The related results were published in the authoritative journals Journal of Quantitative Spectroscopy and Radiative Transfer and IEEE Transactions on Geoscience and Remote Sensing, under the titles "Global High-Spatial-Resolution Cloud Particle Size Distribution Retrieval Using Satellite Multi-Angle Polarimetric Measurements" and "Cloud Reflectance Correction and Retrieval of Cloud Optical Thickness and Effective Particle Radius Based on POSP Observations from GF-5 (02)."

Cloud particle size distribution parameters are key quantities for characterizing cloud optical properties and microphysical processes and for assessing cloud radiative effects. To expand the application scenarios of domestically produced satellite payloads, the project team developed an algorithm for the DPC polarization payload that retrieves high-spatial-resolution cloud particle size distribution parameters from multi-angle polarimetry based on dynamic pixel aggregation. By fully exploiting multi-angle polarimetric observations and accounting for contributions from neighboring pixels, the algorithm optimizes the spatial aggregation scale while ensuring adequate sampling of polarization information in the cloud bow region, raising the spatial resolution of the multi-angle polarimetric cloud particle size distribution product to nearly 3.3 km, close to the native resolution of DPC observations. Compared with the nearly 150 km resolution of foreign POLDER satellite products, this enables high-resolution retrieval of effective radius and effective variance for water clouds on a global scale. For the POSP polarization payload, the team developed a near-infrared–shortwave-infrared dual-channel retrieval algorithm based on radiative transfer simulation and cloud reflectance correction. Quantitative assessment of the sensitivity of different channel combinations to cloud microphysical parameters identified 0.865–2.25 µm as the optimal dual-channel combination. Meanwhile, cloud reflectance correction based on a radiative transfer model increased the proportion of pixels with valid cloud parameter retrievals by 52.06%. Cloud optical thickness and effective particle radius were retrieved for global water and ice clouds in 2023, and the results showed good consistency with mainstream international MODIS and VIIRS satellite cloud products.

This work was supported by the National Key R&D Program of China, the China Postdoctoral Science Foundation, and the Anhui Provincial Postdoctoral Science Foundation. Dr. Yu Haixiao, a postdoctoral researcher, and Zhou Yicheng, a master's student, are the first authors of the two papers, and Researcher Chen Cheng is the corresponding author.

Paper1:https://doi.org/10.1016/j.jqsrt.2026.109938

Paper2:https://doi.org/10.1109/TGRS.2026.3731766

GF-5 (02) DPC global cloud particle size distribution retrieval results and comparative validation

GF-5 (02) POSP global cloud effective particle radius and cloud optical thickness retrieval results and comparative validation