Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areas

Marine aerosols are crucial for ocean–atmosphere interactions. However, there is a lack of analysis on the long-term aerosol optical characteristics and relative humidity (RH) based on large-scale ocean regions. This paper addresses this issue by analyzing the spatiotemporal variations of aerosols i...

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Main Authors: Jie He, Zhao Li, Linyu He, Jian Wang, Weiping Jiang
Format: Article
Language:English
Published: Taylor & Francis Group 2025-01-01
Series:Geo-spatial Information Science
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Online Access:https://www.tandfonline.com/doi/10.1080/10095020.2024.2447445
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author Jie He
Zhao Li
Linyu He
Jian Wang
Weiping Jiang
author_facet Jie He
Zhao Li
Linyu He
Jian Wang
Weiping Jiang
author_sort Jie He
collection DOAJ
description Marine aerosols are crucial for ocean–atmosphere interactions. However, there is a lack of analysis on the long-term aerosol optical characteristics and relative humidity (RH) based on large-scale ocean regions. This paper addresses this issue by analyzing the spatiotemporal variations of aerosols in China’s offshore waters from 2007 to 2022 using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and European Centre of Medium-range Weather Forecasts Reanalysis v.5 (ERA5) data. The results show that in the sea area, the aerosol backscatter coefficient at 532 nm and extinction coefficient at 532 nm increase with increasing RH; the aerosol depolarization ratio decreases with increasing RH. The optical properties of aerosols are generally lower in summer, while they fluctuate with rising RH in other seasons. Notably, the values recorded in 2014–2019 were markedly lower than those in 2007–2013. Nevertheless, from 2020 to 2022, the proportion of aerosol types remained largely stable compared to that of 2014–2019, suggesting a negligible impact of the COVID-19 pandemic on emissions, but the near-shore waters’ aerosol optical properties were more sensitive to minor changes than those of far-off waters. After dividing the China’s offshore waters, the overall optical properties of aerosols decreased in order of the Bohai Sea and Yellow Sea, the East China Sea, and the South China Sea, due to the proportion of marine aerosols increase toward the south. After dividing the altitude layer in the sea area, within the range of 0–7 km, the higher the altitude, the less oceanic aerosols and the more terrestrial aerosols. The aerosol depolarization ratio rises, while the aerosol backscatter coefficient at 532 nm and extinction coefficient at 532 nm alternate downwards. We speculate this is linked to the steep decline in total aerosol content as altitude rises. Our results could provide theoretical references for further deepening the understanding of aerosol generation mechanisms in China’s offshore waters.
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spelling doaj-art-6f1fcdda145b4366b2bacae4ad0f21862025-01-17T14:35:09ZengTaylor & Francis GroupGeo-spatial Information Science1009-50201993-51532025-01-0111810.1080/10095020.2024.2447445Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areasJie He0Zhao Li1Linyu He2Jian Wang3Weiping Jiang4GNSS Research Center, Hubei Luojia Laboratory, Wuhan University, Wuhan, ChinaGNSS Research Center, Hubei Luojia Laboratory, Wuhan University, Wuhan, ChinaSchool of Geodesy and Geomatics, Wuhan University, Wuhan, ChinaGNSS Research Center, Hubei Luojia Laboratory, Wuhan University, Wuhan, ChinaGNSS Research Center, Hubei Luojia Laboratory, Wuhan University, Wuhan, ChinaMarine aerosols are crucial for ocean–atmosphere interactions. However, there is a lack of analysis on the long-term aerosol optical characteristics and relative humidity (RH) based on large-scale ocean regions. This paper addresses this issue by analyzing the spatiotemporal variations of aerosols in China’s offshore waters from 2007 to 2022 using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and European Centre of Medium-range Weather Forecasts Reanalysis v.5 (ERA5) data. The results show that in the sea area, the aerosol backscatter coefficient at 532 nm and extinction coefficient at 532 nm increase with increasing RH; the aerosol depolarization ratio decreases with increasing RH. The optical properties of aerosols are generally lower in summer, while they fluctuate with rising RH in other seasons. Notably, the values recorded in 2014–2019 were markedly lower than those in 2007–2013. Nevertheless, from 2020 to 2022, the proportion of aerosol types remained largely stable compared to that of 2014–2019, suggesting a negligible impact of the COVID-19 pandemic on emissions, but the near-shore waters’ aerosol optical properties were more sensitive to minor changes than those of far-off waters. After dividing the China’s offshore waters, the overall optical properties of aerosols decreased in order of the Bohai Sea and Yellow Sea, the East China Sea, and the South China Sea, due to the proportion of marine aerosols increase toward the south. After dividing the altitude layer in the sea area, within the range of 0–7 km, the higher the altitude, the less oceanic aerosols and the more terrestrial aerosols. The aerosol depolarization ratio rises, while the aerosol backscatter coefficient at 532 nm and extinction coefficient at 532 nm alternate downwards. We speculate this is linked to the steep decline in total aerosol content as altitude rises. Our results could provide theoretical references for further deepening the understanding of aerosol generation mechanisms in China’s offshore waters.https://www.tandfonline.com/doi/10.1080/10095020.2024.2447445Aerosoloptical propertiesCALIPSOERA5China’s offshore
spellingShingle Jie He
Zhao Li
Linyu He
Jian Wang
Weiping Jiang
Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areas
Geo-spatial Information Science
Aerosol
optical properties
CALIPSO
ERA5
China’s offshore
title Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areas
title_full Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areas
title_fullStr Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areas
title_full_unstemmed Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areas
title_short Long-term spatiotemporal features of aerosol optical characteristics and relative humidity in China’s offshore areas
title_sort long term spatiotemporal features of aerosol optical characteristics and relative humidity in china s offshore areas
topic Aerosol
optical properties
CALIPSO
ERA5
China’s offshore
url https://www.tandfonline.com/doi/10.1080/10095020.2024.2447445
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