Aerosol particles over the Bay of Bengal – characteristic, variability and sources – a comprehensive measurement and analysis approach during the BIOCAT-IIOE2 (Aerosol-BIOCAT)

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Aerosol particles are important climate drivers as they scatter and absorb solar radiation and impact the formation and characteristics of clouds. To better understand the diverse climatic effects of aerosol particles, a proper understanding of the aerosol sources and processing is required that is to date still largely missing. Few information on the variability of aerosol chemical properties regarding their temporal and spatial resolution as well as information on their mixing state exist to date. The strength of continental and anthropogenic emissions on the aerosol particles over the ocean in general, and over northern part of the Indian Ocean in particular, is little understood and poorly-quantified, causing strong uncertainties in the estimation of the climate effect of marine aerosols. Within the project Aerosol-BIOCAT we aim to fill the big gaps of knowledge that exist concerning the variability, sources, and environmental drivers on the aerosol particles over the Bay of Bengal (BoB) by applying elaborated field measurements and statistical analysis. We will participate in the BIOCAT-IIOE2 research cruise with R/V Sonne (SO305/BIOCAT) and with Aerosol-BIOCAT we will perform the main atmospheric research component in this cruise. To this end, we will use a combination of online aerosol physico-chemical measurements associated to a comprehensive chemical characterization of the aerosols and the marine sea surface microlayer (SML). A unique data set of aerosol characteristics will be obtained, and advance receptor models will be performed on the dataset allowing a quantitative attribution of different aerosol sources during the North-East monsoon over two transects of the BoB (South-North and North-South). The physical measurements with the high temporal resolution will allow to observe aerosol dynamics (e.g. the formation of new particles) or transitions between aerosol types. The chemical analysis of seawater and especially of the SML will deliver a first-time dataset that will provide new insights into the transfer of organic matter from the ocean to the atmosphere as well as the deposition of black carbon to the ocean surface in the BoB region and the role of SML on Ice nucleating particles (INP). These investigations will allow a proper understanding of marine sources and add valuable information to the enhanced SML dataset existent at TROPOS. Overall, within the presented project new, quantitative information about the marine and non-marine origin and further processing of atmospheric aerosol particles in the BoB during the North-East monsoon will be obtained. The results will help to reduce the gaps of knowledge regarding the importance of natural (oceanic, dust) and anthropogenic sources in polluted marine regions. The expected results will be extremely valuable for better modeling particle transport over the ocean and improve the prediction on their climate effects.