VALIDATION AND COMPARISON OF FINE-MODE AEROSOL OPTICAL DEPTH PRODUCTS BETWEEN MODIS AND POLDER

oleh: B. Y. Ge, B. Y. Ge, Z. Q. Li, W. Z. Hou, Y. Zhang, K. T. Li

Format: Article
Diterbitkan: Copernicus Publications 2019-10-01

Deskripsi

Fine-mode aerosol usually comes from anthropogenic emissions. The fine-mode aerosol optical depth (AOD<sub>f</sub>) is an important parameter for estimating the particulate matter with an aerodynamic diameter little than 2.5&thinsp;&mu;m (PM<sub>2.5</sub>). Compared to the ground-based observations, AOD<sub>f</sub> products from satellite remote sensing have an advantage of high spatial coverage, which is suitable for monitoring the air quality at a regional or global scale. Up to now, AOD<sub>f</sub> products have been released by several sensors, such as the single-angle multi-spectral intensity sensor MODIS and multi-angle multi-spectral polarization sensor POLDER, then what’re the different performances of AOD<sub>f</sub> products from them? In this study, the different spatial resolution AOD<sub>f</sub> products respectively from MODIS latest Collection 6.1 (C6.1, 3 and 10&thinsp;km) and POLDER latest level 2 version 1.01 (L2, 18&thinsp;km) were firstly compared with each other in Beijing-Tianjin-Hebei (BTH) domains. Then those products were validated against the ground-based AERosol RObotic NETwork (AERONET) measurements, where has been suffering the severe air pollution since decades ago. The comparison of yearly averaged AOD<sub>f</sub> products between MODIS and POLDER shows a good consistency on the spatial distribution, the higher spatial resolution products of MODIS show more details, both low values of AOD<sub>f</sub> appeared in the northwest area with small population and industry, high values appeared in the southeast area with lots of cities, industries, and large population. However, the whole yearly AOD<sub>f</sub> average values of MODIS are higher than that of POLDER. The results of validation against AERONET show that the accuracy of AOD<sub>f</sub> products at 865&thinsp;nm from POLDER (R&thinsp;=&thinsp;0.94, RMSE&thinsp;=&thinsp;0.05) is high than that at 550 nm of MODIS (3&thinsp;km: R&thinsp;=&thinsp;0.69, RMSE&thinsp;=&thinsp;0.32; 10&thinsp;km: R&thinsp;=&thinsp;0.76, RMSE&thinsp;=&thinsp;0.3). In this study, the performance of different spatial resolutions AOD<sub>f</sub> products retrieved from the intensity (MODIS 3 and 10&thinsp;km) and polarized sensors (POLDER 18&thinsp;km) were evaluated. Those results not only have a great significance to provide users amore appropriate choice of the AOD<sub>f</sub> products in the BTH region but also display that the accuracy and spatial resolution of MODIS and POLDER AOD<sub>f</sub> products need to be improved.