Spatial distributions and variability of suspended particulate matter in warm-core ring 82B

Abstract

Spatial distributions and variability of suspended particulate matter (SPM) were determined optically during CTD/transmissometer surveys of warm-core ring (WCR) 82B and surrounding waters in June 1982. SPM distributions within 30 km of ring center from the surface to the depth of the 27.6 kg m −3 potential density surface at 800 m were different from surrounding waters. Waters within this core region of the ring had higher SPM concentrations between potential densities of 26.0 and 26.75 kg m −3 and had lower concentrations between 26.8 and 27.5 kg m −3 when compared to sorrounding waters. This result suggests that processes within WCR 82B (as opposed to lateral exchange processes with surrounding waters) were most important in governing particle distributions near ring center. Such isolation was not true for entrainment zone waters 70–80 km from ring center. In this region, waters shallower than 100 m showed a strong influence of waters from the continental shelf. In the entrainment zone, SPM concentrations between the 26.8 and 27.5 kg m −3 potential density surfaces (between 100 and 380 m) were higher compared with waters of similar density both within the ring and in the surrounding Slope Water. In addition, higher SPM concentrations were found in the region of offshore flow behind the ring than in the onshore flow ahead of the ring. This produces a net offshore transport of SPM by WCR 82B for entrainment zone waters of this potential density interval of between 2900 and 15,800 g SPM s −1. These results suggest that WCR's may be very important in the dispersal of resuspended continental slope sediments 100–200 km away from the continental margin.