Performance evaluation for retrieving aerosol optical depth from the Directional Polarimetric Camera (DPC) based on the GRASP algorithm

• Published in: Atmospheric Measurement Techniques
• Main Authors: S. Jin, Y. Ma, C. Chen, O. Dubovik, J. Hong, B. Liu, W. Gong
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2022
• Subjects: Environmental engineering; TA170-171; Earthwork. Foundations; TA715-787; Aerosol Robotic Network
• Online Access: https://doi.org/10.5194/amt-15-4323-2022; https://doaj.org/article/d838d472aa4e415282ff59f29e3a4a67

Aerosol spatial distribution obtained from satellite sensors is critical for understanding regional aerosol environments, anthropogenic aerosol emissions, and global climate change. The Directional Polarimetric Camera (DPC) is the first generation of multi-angle polarized sensor developed by China. It is on-board the GaoFen-5 satellite, running in 705 km sun-synchronous orbit with a 13:30 LT (local time) ascending node. The sensor has three polarized channels at 490, 670, and 865 nm and ∼ 9 viewing angles, mainly used for observing aerosols. The spatial resolution is ∼ 3.3 km at nadir, and global coverage is ∼ 2 d. In this study, the performance of aerosol optical depth (AOD) retrievals from the DPC/GaoFen-5 using the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm were evaluated on a global basis for the first time. The results showed that the DPC GRASP/Model scheme, which used several forms of aerosol-type mixing, achieved good performance. By comparing with Aerosol Robotic Network (AERONET) observations, the correlation coefficient ( R ), root-mean-square error (RMSE), and expected error (EE%, ± ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">0.05</mn><mo>+</mo><mn mathvariant="normal">0.15</mn><mo>×</mo><mtext>AOD</mtext></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="91pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="4168191c55c8c10951e3e354800de9c3"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-4323-2022-ie00001.svg" width="91pt" height="11pt" src="amt-15-4323-2022-ie00001.png"/></svg:svg> )) were 0.9007 %, 0.0662 %, and 82.54 %, respectively. The scattering angle, number of averaged pixels, length of time steps, and radiative and polarized fitting residuals showed impacts on the results of AOD retrieval in the DPC ...