First High-Frequency Underway Observation of DMS Distribution in the Southern Ocean during Austral Autumn

Intae Kim,Miming Zhang,Keyhong Park,Kitae Kim

doi:10.3390/atmos12010122

Intae Kim, Miming Zhang + Show 2 more

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https://doi.org/10.3390/atmos12010122

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Abstract

We investigate the distribution of dimethyl sulfide (DMS) in the Southern Ocean’s (50° W to 170° W) surface water, including the Antarctic Peninsula and the marginal sea ice zone (MIZ) in the Ross and Amundsen Seas. This is the first high-frequency observation conducted in the austral autumn (in April) in the Southern Ocean. The mean DMS concentration was 2.7 ± 2.5 nM (1 σ) for the entire study area. Noticeably enhanced DMS (5 to 28 nM) concentrations were observed in the MIZ around the Ross and Amundsen Seas and the coastal regions in the Antarctic Peninsula; this could be attributed to biological production of local ice algae, which appears to be supplied with nutrients from glacial or sea ice melt water. These observed DMS inventories were significantly higher (an order of magnitude) than current climatological DMS inventories. The local DMS sources being transported outward from the polynyas, where strong bloom occurs during summer, could result in larger discrepancies between observed DMS and climatological DMS in the MIZ area (in the Amundsen Sea). Overall, this study is the first to highlight the significance of the underestimation of current DMS fluxes in the austral autumn, which consequently results in significant errors in the climate models.

Highlights

Dimethyl sulfide (DMS) is a volatile organic compound produced from the biological activity of plankton in the ocean through the decomposition of algal metabolites, such as dimethylsulfoniopropionate (DMSP)
We investigated the surface dimethyl sulfide (DMS) distribution in the Southern Ocean in April, a period when the DMS distributions are rarely studied
DMS (5 to 30 nM) concentrations were observed in the marginal ice zone (MIZ) in the western Antarctic and coastal waters around the Antarctic Peninsula, using a high frequency observation

Summary

Introduction

Dimethyl sulfide (DMS) is a volatile organic compound produced from the biological activity of plankton in the ocean through the decomposition of algal metabolites, such as dimethylsulfoniopropionate (DMSP). The overall role of DMS in the climate system is still under debate [3], the influence of DMS could be significant at the regional scale in remote oceans, such as the polar oceans [4,5]. Antarctic polynyas could be a key DMS source region due to the dominance of Phaeocystis antarctica (P. antarctica) in Antarctic water phytoplankton assemblages, which is considered to be a main producer of the DMSP as a DMS precursor [9,10,11]. Approximately two-fold higher mean concentrations (up to 300 nM) and fluxes of DMS have recently been reported from the surface waters of western Antarctica as com-

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