A pseudo-Lagrangian study of the sulfur budget in the remote Arctic marine boundary layer

Abstract

The atmospheric sulfur cycle of the remote Arctic marine boundary layer is studied using trajectories and measurements of sulfur compounds from the International Arctic Ocean Expedition 1991, along with a pseudo-Lagrangian approach and an analytical model. The dimethyl sulfide [DMS(g)] turnover time was 59^+18-9h. Only 25⁺¹¹_-9% of DMS(g) followed reaction paths to sulfur dioxide [SO₂(g)], sub-micrometre aerosol non-seasalt sulfate (nss-SO₄²⁻) or methane sulfonate (MSA). During the first 3 d of transport over the pack ice, fog deposition and drizzle resulted in short turnover times; 16⁺⁸_-6 h for SO₂(g), 18⁺⁴_-4h for MSA and 18^+2-3 h for nss-SO₄²⁻. Therefore, DMS(g) will, owing to its origin along or south of the ice edge and longer turnover time, survive the original sub-micrometre sulfur aerosol mass and gradually replace it with new biogenic sulfur aerosol mass. The advection of DMS(g) along with heat and moisture will influence the clouds and fogs over the Arctic pack ice through the formation of cloud condensation nuclei (CCN). If the pack ice cover were to decrease owing to a climate change, the total Arctic Ocean DMS production would change, and potentially there could be an ice–DMS–cloud–albedo climate feedback effect, but it would be accompanied by changes in the fog aerosol sink.