Role of sea level pressure in variations of the Canadian Arctic Archipelago throughflow

Abstract

The throughflow in the Canadian Arctic Archipelago (CAA) had a significant impact on the North Atlantic Ocean with the Arctic climate change. The findings of physical mechanisms driving the throughflow in the CAA differed and few studies about the impact of sea level pressure (SLP) on the CAA throughflow were made. A high-resolution ice-ocean coupled Arctic Ocean Finite-Volume Community Ocean Model (AO-FVCOM) was used over the period 1978–2016 to examine the interannual and seasonal variability of the outflows in the CAA and the mechanism of SLP in driving the variation of the CAA throughflow quantitively. The simulated volume transport through Davis Strait, Nares Strait, Lancaster Sound and Jones Sound showed consistent increasing trends over 1978–2016 and the larger flux in winter and spring than in summer and fall. The variation of volume transport through Nares Strait contributed more than Lancaster and Jones Sound to the variation through Davis Strait. Five process-oriented experiments were made to further explore the role of SLP in setting up and controlling the sea surface height (SSH) difference and thus the throughflow transport in the CAA. The SLP was a primary forcing to control the SSH difference and the outflow transport compared with the wind forcing. The memory of the SSH to the SLP was short and an equilibrium state could be reached if the SLP varied with time. The upstream and downstream SLP difference, however, made a slight direct contribution to driving the volume transport of the CAA throughflow. In addition to the external forcing of SLP and wind, the variability of the CAA outflow was also influenced by the variability of the inflow/outflow and SSH on boundaries connected to the Pacific and Atlantic Oceans. The choice of SLP datasets from CORE-v2, ECMWF and NCEP was sensitive to the simulated uncertainty of volume transport.