Spatial predictions of sea surface dimethylsulfide concentrations in the high arctic

Abstract

The climatically-important compound dimethylsulfide (DMS) has been reported to be abundant in the Arctic, particularly in the marginal sea ice zone. Due to these high concentrations, it may play an important role in climate control. A DMS monthly climatology for July through October was created employing various ocean characteristics and spatial modeling techniques commonly used for describing species distributions in ecology. Comparisons between observed and predicted values of surface seawater DMS concentrations led to r 2 values of 0.61, 0.87, 0.66, and 0.37 for July, August, September, and October, respectively. Measurement data used for model development for July through October were variably distributed spatially. For October only, data were sparse and clustered, resulting in the poor results obtained for this month. Mean sea ice concentration and surface nitrate concentrations were found to be important predictors of surface seawater DMS concentrations. A negative relationship between sea ice concentration and DMS, and a two-phase relationship between nitrate and DMS were found. The two-phase relationship may be indicative of how DMS concentrations are affected when nitrate is the limiting nutrient. From July to September, predicted DMS concentrations were generally lowest under the sea ice. High monthly DMS concentrations (up to 10.7 nM) were predicted in the seasonal ice zone. The highest DMS concentrations in September (~2.6 nM) were predicted along the ice edge. In order to create more accurate climatologies and to increase our understanding of sulfur cycling in the Arctic, a higher spatial and temporal distribution of DMS measurements is required.