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Abstract In tidewater glacier fjords, subglacial discharge drives a significant mixing mechanism near glacier fronts and drives a strong exchange flow. Numerous studies (Cowton et al., 2015,https://doi.org/10.1002/2014jc010324; Slater et al., 2017,https://doi.org/10.1002/2016gl072374) have utilized a parameterization for buoyant plume theory to force fjord scales systems, but neglect to parameterize the outflowing of the plume away from the glacial wall after it has reached its neutral density. In this study, a new model framework, ROMS‐ICEPLUME, is developed to parameterize the rising and initial outflowing stage of subglacial discharge plumes in the Regional Ocean Modeling System. The coupled model applies a novel parameterization algorithm to prescribe the velocity and vertical extent of the outflowing plume, which reduces numerical instability and improves model performance. The model framework is tested with a quasi‐realistic forcing using observations of a subglacial discharge plume hydrographic surveys collected from a Greenland fjord. We find that the new model framework is able to reproduce the strong outflowing plume and the compensating inflow at depth, with a spatial structure that correlates well with in‐situ observations. On the other hand, the model framework without the new parameterization algorithm fails to capture the outflowing plume structure. Thus, our new framework for parameterizing subglacial discharge plumes is an improvement from previous coupled model frameworks, and is a promising tool toward advancing our understanding of circulation in tidewater glacier fjords.
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Application of Symmetric Instability Parameterization in the Coastal and Regional Ocean Community Model (CROCO)
Abstract As one kind of submesoscale instability, symmetric instability (SI) of the ocean surface mixed layer (SML) plays a significant role in modulating the SML energetics and material transport. The small spatial scales of SI,O(10 m–1 km), are not resolved by current climate ocean models and most regional models. This study describes comparisons in an idealized configuration of the SI parameterization scheme proposed by Bachman et al. (2017,https://doi.org/10.1016/j.ocemod.2016.12.003) (SI‐parameterized) versus the K‐Profile Parameterization scheme (SI‐neglected) as compared to a SI‐permitting model; all variants use the Coastal and Regional Ocean Community Model version of the Regional Ocean Modeling System and this study also serves to introduce the SI parameterization in that model. In both the SI‐parameterized and SI‐permitting models, the geostrophic shear production is enhanced and anticyclonic potential vorticity is reduced versus the SI‐neglected model. A comprehensive comparison of the energetics (geostrophic shear production, vertical buoyancy flux), mixed layer thickness, potential vorticity, and tracer redistribution indicate that all these variables in the SI‐parameterized case have structures closer to the SI‐permitting case in contrast to the SI‐neglected one, demonstrating that the SI scheme qualitatively improves representation of the impacts of SI. This work builds toward applying the SI scheme in a realistic regional or climate model.
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- Award ID(s):
- 1655221
- PAR ID:
- 10363950
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Advances in Modeling Earth Systems
- Volume:
- 13
- Issue:
- 3
- ISSN:
- 1942-2466
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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