Meeting Documents

Modeling the Pathway of Atlantic Water and the Impact of Glacial Discharge

Abstract

Mass loss from the Greenland ice sheet (GrIS) has been increasing for the past decades. GrIS mass loss is driven primarily by the buoyancy plume at the glacier front, which entrains warm Atlantic water into the fjord. In the open ocean, the warm AW transport by West Greenland Current (WGC) is suggested to be controlled by the North Atlantic Oscillation. However, it is still unclear how AW intrudes from the open ocean onto the continental shelf and travels into fjords toward glaciers as most previous studies rely on large-scale global simulations or highly regional idealized cavity simulations. Here, we develop a regional ocean model in West Greenland downscaled from ECCO LLC 270 global state estimate for 26 years (1992-2017) using the Massachusetts Institute of Technology general circulation model (MITgcm). Horizontal grid spacing is 2-3km. The vertical discretization comprises 70 levels varying in thickness. We employ the ice plume model and force the model using the subglacial freshwater discharge calculated by Model Atmospheric Regional (MAR) over the land and ice areas of Greenland. We compare our simulated output with existing ship-based observations, Argo floats, and moorings. We further investigate AW variability along WGC by comparing the model and observations focusing on the water mass distributions, properties, and variabilities. Our model simulates the warming trend of 0.18°C per year at the front of Jakobshavn Glacier. The model also simulates high seasonal variabilities from Davis Strait to Jakobshavn Glacier with temperature peaks identified from November to July. We find the simulated temperature fluctuates seasonally and interannually. We also conduct sensitivity experiments with ice plume parameterization and with an equal amount of freshwater flux only at the surface. Implementation of ice plume parameterization improves the simulated hydrographic structure including the temperature inside of the fjord increased by 0.3 °C. These sensitivity experiments highlight the importance of subglacial freshwater discharge in enhancing the AW inflow into West Greenland fjords.