Deep Blue Retrievals of Asian Aerosol Properties During ACE-Asia

TLDR

The ACE‑Asia field campaign collected unprecedented aerosol data over East Asia in spring, yet most observations were downwind of source regions, and the season is marked by frequent cloudiness and diverse aerosol loadings. This study applies the Deep Blue satellite aerosol algorithm to SeaWiFS and MODIS radiances to characterize aerosol properties over source regions and examines how environmental complexity affects monthly satellite aerosol averages and product synergy. Deep Blue derives the Ångström exponent from SeaWiFS and MODIS radiances and its results are validated against AERONET sunphotometer observations from China and Mongolia in spring 2001. The algorithm successfully separates dust plumes from fine‑mode pollution, retrieves aerosol optical thickness within 20–30 % of AERONET values, and shows that mineral dust and anthropogenic particles contribute similarly in northern China while fine‑mode particles dominate in southern China.

Abstract

During the ACE-Asia field campaign, unprecedented amounts of aerosol property data in East Asia during springtime were collected from an array of aircraft, shipboard, and surface instruments. However, most of the observations were obtained in areas downwind of the source regions. In this paper, the newly developed satellite aerosol algorithm called "Deep Blue" was employed to characterize the properties of aerosols over source regions using radiance measurements from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS). Based upon the Aringngstroumlm exponent derived from the Deep Blue algorithm, it was demonstrated that this new algorithm is able to distinguish dust plumes from fine-mode pollution particles even in complex aerosol environments such as the one over Beijing. Furthermore, these results were validated by comparing them with observations from AERONET sites in China and Mongolia during spring 2001. These comparisons show that the values of satellite-retrieved aerosol optical thickness from Deep Blue are generally within 20%-30% of those measured by sunphotometers. The analyses also indicate that the roles of mineral dust and anthropogenic particles are comparable in contributing to the overall aerosol distributions during spring in northern China, while fine-mode particles are dominant over southern China. The spring season in East Asia consists of one of the most complex environments in terms of frequent cloudiness and wide ranges of aerosol loadings and types. This paper will discuss how the factors contributing to this complexity influence the resulting aerosol monthly averages from various satellite sensors and, thus, the synergy among satellite aerosol products