Großelindemann, Hendrik (2020) Marine heatwaves on the Northeast US continental shelf. (Bachelor thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 31 pp.

Preview

Text Marine_Heatwaves_on_the_Northeast_US_continental_shelf.pdf - Published Version Available under License Creative Commons: Attribution 4.0. Download (15MB) | Preview

Abstract

Marine Heatwaves (MHWs) are climate events characterized by anomalously high temperatures that can have devastating impacts on ecosystems and therefore also on fisheries. MHWs increase in duration, frequency and intensity globally. Due to the lack of subsurface observations, the current knowledge about MHWs is mainly based on the surface, although MHWs have known impacts on pelagic and benthic ecosystems as well. This study investigates the depth structures of MHWs on the northeast US continental shelf with an ocean circulation model of 1/20° resolution. The Northwest Atlantic is one of the most rapidly warming regions in the world and as a consequence acutely exposed to MHWs. The shelf region especially is highly biologically productive resulting in a large fishing industry. Enormous impacts of MHWs have already been experienced in the recent decade. This study highlights a significant increase of MHWs duration and intensity on the shelf during the last 40 years, based on observed satellite SST data. It then briefly validates the effect of model resolution in resolving the prevailing ocean dynamics in this region that may be relevant for the generation of MHWs. It is shown that MHWs occur in various spatial extents. Some events appear only at the surface and are focused on the coastal region, whereas other events appear at depth at the shelf break, without reaching the surface. In addition, events occur which affect the whole water column. The highest temperature anomalies can be found at depth at the shelf break. Furthermore, associated salinity anomalies show similar patterns to temperature in deep events, whereas surface events show no connection of salinity and temperature. These discrepancies indicate different MHW drivers. Surface events can be likely linked to atmosphere ocean interactions. Deep events reveal Gulf Stream warm core ring interaction, where the eddy is able to intrude its anonymously warm and salty waters on to the shelf. Hence, MHW formation depends on the local dynamics whose better understanding is therefore necessary. This study shows the possible impacts of deep events and thus underlines the need of continuous subsurface measurements to detect MHWs at depth. Furthermore, this study reveals the opportunities of climate models to investigate MHWs, their characterization and associated drivers.

Actions (login required)

View Item