Unraveling the Controls on Arctic Ocean Salinity Stratification Through E3SM-Arctic Tracer Release Experiments
Carlyn Schmidgall, University of Washington
The Arctic Ocean is an epicenter for anthropogenic climate change, with rapid warming and sea ice loss driving complex changes to the ice-ocean-atmosphere system. As the Arctic climate shifts, so has the balance of its freshwater transport, storage, and distribution. Inflow from the Pacific and Atlantic Oceans, rivers, precipitation, and sea ice processes all impact the Arctic Ocean freshwater budget. Salinity stratification— the layering of the ocean, with fresh waters at the surface and saltier waters below— modulates circulation pathways and mediates the vertical transfer of subsurface oceanic heat. Linking these freshwater fluxes to changes in stratification can allow us to better understand the oceanic processes affecting sea ice decline, as well as the dynamics of the Arctic ice-ocean system as a whole.
Here, we provide an overview of a planned tracer release experiment using the Arctic configuration of the Energy Exascale Earth System Model (E3SM-Arctic) to examine the contribution of these different freshwater fluxes to Arctic Ocean stratification. We will use output from an ocean-sea ice E3SM-Arctic simulation to advect volume and salt tracers from each of the major freshwater sources/sinks in the Arctic Ocean. This tracer release scheme will enable us to determine the contribution of each source/sink to observed freshening at different locations and depths within the model. A primary goal of this study is to analyze how the pathways and storage of different freshwater fluxes are modulated by large-scale and regional-scale atmospheric circulation. Furthermore, we seek to study the depths at which distinct freshwater sources reside and therefore contribute to local stratification, and how this varies across regions of the Arctic and under different atmospheric forcing regimes. This experiment will provide a novel approach to examine how various freshwater fluxes influence Arctic Ocean stratification, and enhance our understanding of Arctic Ocean freshwater dynamics in the context of a changing climate.