Modeling of the influence of sea ice cycle and Langmuir circulation on the upper ocean mixed layer depth and freshwater distribution at the West Antarctic Peninsula

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Schultz, Cristina, Doney, Scott C., Zhang, Weifeng G., Regan, Heather, Holland, Paul R., Meredith, Michael P., Stammerjohn, Sharon E.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2020
• Subjects: West Antarctic Peninsula; sea ice; Langmuir circulation; mixed layer depth; glacial runoff; Antarctic; Antarctic Peninsula; Langmuir; Meredith; Southern Ocean; Antarc*; Sea ice
• Online Access: https://hdl.handle.net/1912/26431

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Schultz, C., Doney, S. C., Zhang, W. G., Regan, H., Holland, P., Meredith, M. P., & Stammerjohn, S. Modeling of the influence of sea ice cycle and Langmuir circulation on the upper ocean mixed layer depth and freshwater distribution at the West Antarctic Peninsula. Journal of Geophysical Research: Oceans, 125(8), (2020): e2020JC016109, doi:10.1029/2020JC016109. The Southern Ocean is chronically undersampled due to its remoteness, harsh environment, and sea ice cover. Ocean circulation models yield significant insight into key processes and to some extent obviate the dearth of data; however, they often underestimate surface mixed layer depth (MLD), with consequences for surface water‐column temperature, salinity, and nutrient concentration. In this study, a coupled circulation and sea ice model was implemented for the region adjacent to the West Antarctic Peninsula, a climatically sensitive region which has exhibited decadal trends towards higher ocean temperature, shorter sea ice season, and increasing glacial freshwater input, overlain by strong interannual variability. Hindcast simulations were conducted with different air‐ice drag coefficients and Langmuir circulation parameterizations to determine the impact of these factors on MLD. Including Langmuir circulation deepened the surface mixed layer, with the deepening being more pronounced in the shelf and slope regions. Optimal selection of an air‐ice drag coefficient also increased modeled MLD by similar amounts and had a larger impact in improving the reliability of the simulated MLD interannual variability. This study highlights the importance of sea ice volume and redistribution to correctly reproduce the physics of the underlying ocean, and the potential of appropriately parameterizing Langmuir circulation to help correct for biases towards shallow MLD in the Southern Ocean. The model also reproduces ...