Temporal and spatial distribution of dimethylsulfide in the subarctic northeast Pacific Ocean: a high‐nutrient–low‐chlorophyll region

• Published in: Tellus. Series B, Chemical and physical meteorology Chemical and physical meteorology, 2005-09, Vol.57 (4), p.317-331
• Main Authors: WONG, C. S., WONG, S. E., RICHARDSON, W. A., SMITH, G. E., ARYCHUK, M. D., PAGE, J. S.
• Format: Article
• Language: English
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Marine; Physical and chemical properties of sea water; Physics of the oceans
• ISSN: 0280-6509; 1600-0889
• DOI: 10.1111/j.1600-0889.2005.00156.x

ABSTRACT Dimethylsulfide (DMS) was measured in the upper 400 m of the northeast Pacific from February 1996 to June 2001. The sampling took place along Line P (48°34.5′N, 125°30′W to 50°N, 145°W). DMS concentrations increased diurnally from a pre‐dawn low to a mid‐day maximum and from coastal waters to open ocean, in a high‐nutrient–low‐chlorophyll‐a (HNLC) water mass. The mean surface DMS in winter was 2 nM, in spring 6 nM and in summer 10 nM. Our June surface DMS amounts were comparable with those obtained by the Pacific Marine Environmental Laboratory. A sea to air flux of DMS at Station P (50°N, 145°W) was high in the summer of 1997 and the early autumn of 1998 and 2000 and was significantly higher than at other Line P stations. The average flux along Line P was 27 μmol m−2 d−1 by Wanninkhof's formula while that by Liss and Merlivat was 16 μmol m−2 d−1. DMS profiles showed a decreasing trend with depth, as did temperature and chlorophyll‐a (Chl‐a), but an increasing trend with salinity and nitrate. Average DMS concentrations at mixed‐layer depth (DMSMLD) were low in winter at an average of 2.4 nM, moderate in spring at 8 nM and high in summer at 16 nM. For open ocean stations P20 and P26 DMSMLD was high, while Chl‐aMLD was low for late spring and early summer during 1996–1998. That is the “summer paradox” phenomenon. The ratio of DMSMLD to Chl‐aMLD was out of phase with the mixed‐layer depth. Our data confirm the high DMS concentrations previously reported for this region and suggest that this is characteristic of the subarctic HNLC region.