Observations and Modeling of Salinity Variability in the Beaufort Gyre
Carlyn Schmidgall, University of Washington
In the polar oceans, salinity exerts the primary control on seawater density, allowing warm, salty layers at depth to be capped by cold, fresh layers near the surface. Vertical gradients in salinity therefore set the stability of the water column, and the tendency for subsurface heat to be mixed upward towards the surface. In the spring and summer, cool and fresh meltwater input from sea ice enhances salinity stratification. The degree to which these freshwater anomalies persist and precondition the ocean for sea ice formation is an open question with ramifications for the dynamics of the Beaufort Gyre, the Arctic cryosphere, and the global climate system. Here we present initial analysis from measurements collected during the 2022 NASA Salinity and Stratification at the Sea Ice Edge (SASSIE) field campaign, which surveyed the Beaufort Gyre during the transition from summer ice melt to autumn ice advance. These observations reveal a high degree of 1-10km scale variability, indicating the importance of small-scale processes in shaping overall patterns of salinity stratification and sea surface temperature. This in situ data will be used to evaluate and improve parameterizations of upper ocean processes in a high resolution numerical model, which has been configured to simulate the period of sea ice freeze-up in the Beaufort Gyre. Future work will integrate both observations and model output to investigate how meltwater modulates stratification, interacts with small-scale ocean dynamics, and ultimately influences sea ice formation.
Abstract Author(s): Carlyn Schmidgall, Peter Gaube, and LuAnne Thompson