Influence of explicit Phaeocystis parameterizations on the global distribution of marine dimethyl sulfide

Abstract

Dimethyl sulfide (DMS) is a biogenic organosulfur compound which contributes strongly to marine aerosol mass and the determination of cloud condensation nuclei over the remote oceans. Since uncertainties in DMS flux to the atmosphere lead to large variations in climate forcing, the global DMS distribution has been the subject of increasingly complex dynamic simulations. DMS concentrations are directly controlled by marine ecosystems. Phaeocystis is a major DMS producer but is often omitted from global reduced sulfur mechanisms. Here we incorporate this phytoplankton group into the marine ecosystem-biogeochemical module of the Community Earth System Model. To examine its role in the ocean sulfur cycle, an earlier DMS model has been enhanced to include new knowledge gained over the last few years. Results from the baseline run show that simulated Phaeocystis biomass generally agrees with observations, with high concentrations near the Antarctic continent and between 50°and 60°north. Given the new explicit Phaeocystis representation, the DMS distribution shows significant improvements, especially regarding the amplitude and location of high-latitude peaks. The simulated global mean surface DMS value is 2.26 nM, comparable to an estimate of 2.34 nM from the latest climatology extrapolated based on observations. The total oceanic DMS source to the atmosphere is 20.4 Tg S/yr, on the low side of previous estimates. Comparisons with and without Phaeocystis show that the group dominates DMS distributions in temperate and cold waters, contributing 13% of the global flux. The proportion may increase as sea ice declines and should be considered in climate projections.

Global distribution and surface activity of macromolecules in offline simulations of marine organic chemistry

“…Through this combination we seek to better define the properties of a major environmental interface-the boundary between sea and air, which is nominally unbroken but complicated by the formation of bubble and atmospheric particle plumes (Liss 1975;Blanchard 1989;Russell et al 2010). We build from the output of a well-established ocean systems model (Moore et al 2002(Moore et al , 2004Elliott et al 2011;Wang et al 2015). This baseline code utilizes a simulated fluid dynamic general circulation to transport resources into the sunlit euphotic zone.…”

“…Organic compound distribution estimates are built up primarily from the global marine ecodynamics framework known as BEC, standing for Biogeochemistry-Ecosystem-Circulation (Moore et al 2004;Letscher et al 2015;Wang et al 2015). This code simulates multielement flow through several trophic levels in the upper ocean, with limitations by the usual nutrient types and light availability.…”

“…BEC ecodynamic tracer fields are imported into our calculations directly from the most recent versions, incorporating improvements which mainly involve phytoplankton-specific parameter settings (Wang et al 2015). Our treatment of the organics involves streamlined parallel kinetics operating conceptually on high molecular weight chains portrayed as individual forms of carbon.…”

Annual cycle of dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) related to phytoplankton succession in the Southern North Sea

“…DMS emissions from the oceans play an important role in the global S cycle, contributing to approximately 40% of the biogenic S emissions (Wang et al, 2015) and could act on climate through the formation of atmospheric aerosols and the modification of cloud albedo (Charlson et al, 1987). However, the significance of this feedback on climate remains uncertain (Quinn and Bates, 2011;Green and Hatton, 2014).…”

Evaluating Uncertainties in Marine Biogeochemical Models: Benchmarking Aerosol Precursors

“…Sea-air ventilation and the vertical transfer of trace greenhouse gases or marine aerosol precursors are closely associated with the dynamics of marine food webs, along with shifts in regional ecosystems [4,[53][54][55][56]. Thus, any shift in nutrient availability within the euphotic layer-coupled to changes in ambient conditions that could influence biomass production in a less direct manner-can affect gas or aerosol loadings in the lower troposphere.…”