Abstract
Understanding aerosols optical properties over the oceans is vital for enhancing our knowledge of aerosol effects on climate and pollutant transport between continents. In this study, the characteristics of aerosol optical thickness (AOT) at 500 nm (τ500nm), Ångström exponent for the wavelength pair 440–870 nm (α) and volume size distribution (VSD), are presented and analyzed over the East China seas based on the observations at four AERONET sites during 1999–2019. The main results are: (1) the mean τ500nm (α) value ranged from 0.31 to 0.36 (1.17–1.31); (2) the distribution of τ500nm (α) is similar to a log-normal distribution with a right-skewed long tail larger than 0.5 (closer to the normal distribution); (3) large AOT (τ500nm>0.6) was frequently observed in summer (June and July) and spring (March to May), followed by autumn and winter; (4) all aerosol types were observed, and urban/industrial aerosols and mixed types were dominant throughout the period. The atmospheric column aerosol was characterized by a bimodal lognormal size distribution with a fine mode at effective radius, Reff = 0.16 ± 0.01 μm, and coarse mode at Reff = 2.05 ± 0.1 μm.
Highlights
Aerosols over the oceans are important for various atmospheric processes and remote sensing studies [1]
The characteristics of aerosol optical thickness (AOT), Ångström exponent (AE), and volume size distribution (VSD) are presented and analyzed over the East China seas based on the observations at four AERONET sites during
The threshold criteria of [23] was used to identify the following different aerosol types: (i) the pure maritime aerosol (MA), which τ500nm < 0.2 and AE < 1.0; (ii) dust aerosol (DA), which τ500nm > 0.2 and AE < 1.0; (iii) urban/industrial aerosols (UIA), which τ500nm > 0.2 and AE > 1.0; (iv) biomass-burning aerosols (BBA), which τ500nm > 0.8 and AE > 1.0; (v) the remaining aerosols were classified as mixedaerosol type (MIX1 and MIX2)
Summary
Aerosols over the oceans are important for various atmospheric processes and remote sensing studies [1]. Anthropogenic aerosols refer to aerosols produced by human activities—such as industrial emissions, urban traffic pollution, and municipal construction These aerosols are composed of substances with different shapes, size distributions, chemical compositions, and optical properties with concentrations varying multiple orders of magnitude. Understanding the size distribution of aerosols will improve our understanding of their environmental impacts and radiative effects It is the basis for satellite remote sensing retrieval and validation because the accuracy of atmospheric correction algorithms depends on the aerosol models. The characteristics of aerosol optical thickness (AOT), Ångström exponent (AE), and volume size distribution (VSD) are presented and analyzed over the East China seas based on the observations at four AERONET sites during
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