Evaluation of JAXA Himawari-8-AHI Level-3 Aerosol Products over Eastern China

Abstract

A novel geostationary satellite, the H8/AHI (Himawari-8/Advanced Himawari Imager), greatly improved the scan times per day covering East Asia, and the operational products have been stably provided for a period of time. Currently, atmospheric aerosol pollution is a major concern in China. H8/AHI aerosol products with a high temporal resolution are helpful for real-time monitoring of subtle aerosol variation. However, the H8/AHI aerosol optical thickness (AOT) product has been updated three times since its launch, and the evaluation of this dataset is currently rare. In order to validate its accuracy, this study compared the H8/AHI Level-3 (L3) hourly AOT products of all versions with measurements obtained from eleven sunphotometer sites located in eastern China from 2015 to 2018. Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 AOT products from the same period were also used for inter-comparison. Although the H8/AHI AOT retrievals in version 010 show a moderate agreement with ground-based observations (correlation coefficient (R): 0.66–0.85), and the time series analysis shows that it can effectively monitor hourly variation, it suffers from an obvious underestimation of 0.3 compared to ground-based and MODIS observations. After the retrieval algorithm updated the predefined aerosol model, the overall underestimation of AHI AOTs was solved (version 010 slope: 0.43–0.62, version 030 slope: 0.75–1.02), and the AOTs in version 030 show a high agreement with observations from ten sites (R: 0.73–0.91). In addition, the surface reflectance dataset derived from the minimum reflectivity model in version 010 is inaccurate in parts of eastern China, for both “bright” and “dark” land surfaces, which leads to the overestimation of the AOT values under low aerosol loads at the Beijing and Xianghe sites. After the update of the surface dataset in version 030, this phenomenon was alleviated, resulting in no significant difference in scatterplots under different surface conditions. The AOTs of H8/AHI version 030 show a significant improvement compared to the previous two versions, but the spatial distribution of AHI is still different from MODIS AOT products due to the differences in sensors and algorithms. Therefore, although the evaluation in this study demonstrates the effectiveness of H8/AHI AOT products for aerosol monitoring at fine temporal resolutions, the performance of H8/AHI AOT products needs further study by considering more conditions.

Hourly PM2.5 Estimates from a Geostationary Satellite Based on an Ensemble Learning Algorithm and Their Spatiotemporal Patterns over Central East China

“…MODIS Terra and Aqua 3-km AOD retrievals with the highest confidence levels from pixels falling within 5 km of each PM 2.5 site were averaged and matched with the training dataset. AHI AODs are significantly and systematically lower than MODIS AODs with large RMSE and MPE, consistent with previous studies (e.g., [47,54]). PM 2.5 concentrations are also estimated from AHI and MODIS AODs using the RF algorithm.…”

“…Since the accuracy evaluation of Himawari-8 aerosol products is limited, studies have shown that the accuracy of Himawari-8 AOD retrievals still needs to be improved compared with surface Aerosol Robotic Network and MODIS retrievals [47]. The AHI-retrieved AOD over Eastern China suffers from an obvious underestimation compared with ground-based and MODIS observations [54]. Figure S12 shows a comparison of AHI and MODIS AODs over all PM 2.5 sites.…”

Validation and Accuracy Assessment of MODIS C6.1 Aerosol Products over the Heavy Aerosol Loading Area

“…It provides a dataset of spectral AOD in the range of 0.340-1.060 µm with low uncertainty (~0.01-0.02) and high temporal resolution (every 15 min) under cloud-free conditions [29]. AERONET observations have been widely adopted for the validation of satellite-retrieved AOD [28,30,31]. For the validation of MODIS aerosol products over the heavy aerosol loading area, this study used the version 3 cloud-screened and quality-controlled level 2.0 AOD ground-based observations from 23 AERONET sites during 2000 to 2016, as shown in Figure 1, which are located in regions above the annual average WHO IT-1 value for PM 2.5 of 35 µg/m 3 , and with at least 500 days of measurements.…”

“…Atmosphere 2018, 9, x FOR PEER REVIEW 3 of 16 [28,30,31]. For the validation of MODIS aerosol products over the heavy aerosol loading area, this study used the version 3 cloud-screened and quality-controlled level 2.0 AOD ground-based observations from 23 AERONET sites during 2000 to 2016, as shown in Figure 1, which are located in regions above the annual average WHO IT-1 value for PM2.5 of 35 μg/m 3 , and with at least 500 days of measurements.…”

Comparison of hourly aerosol retrievals from JAXA Himawari/AHI in version 3.0 and a simple customized method

“…As for the latest version, Wang et al 35 found that the AHI Level 3 (L3) hourly AOD retrievals were generally fit well with AERONET measurements in Beijing, but still with a slight underestimation. Li et al 36 concluded that the AHI level 3 version 3.0 hourly aerosol products presented a better agreement with AERONET than previous two versions (1.0 and 2.0) over eastern China. Zhang et al 37 validated the performance of AHI L3 AOD merged against AERONET AOD over land and revealed the regional and seasonal difference of AHI retrievals.…”