Title: Preconditioning and Formation of Maud Rise Polynyas in a High-Resolution Earth System Model

Abstract

Open-ocean polynyas (OOPs) in the Southern Ocean are ice-free areas within the winter ice pack that are associated with deep convection, potentially contributing to the formation of Antarctic Bottom Water. To enhance the credibility of Earth system models (ESMs), their ability to simulate OOPs realistically is thus crucial. Here we investigate OOPs that emerge intermittently in a high-resolution (HR) preindustrial simulation with the Energy Exascale Earth System Model, version 0.1 (E3SMv0), an offspring of the Community Earth System Model (CESM). While low-resolution (LR) simulations with E3SMv0 show no signs of OOP formation, the preindustrial E3SMv0-HR simulation produces both large Weddell Sea polynyas (WSPs) as well as small Maud Rise polynyas (MRPs). The latter are associated with a prominent seamount in the eastern Weddell Sea, and their preconditioning and formation is the focus of this study. The steep flanks of the rugged topography in this region are in E3SMv0-HR sufficiently well resolved for the impinging flow to produce pronounced Taylor caps that precondition the region for convection. Aided by an accumulation of heat in the Weddell Deep Water layer, the ultimate trigger of convection that leads to MRPs is the advection of anomalously high upper-ocean-layer salinity. The crucial difference to WSP-producingmore » LR ESM simulations is that in E3SMv0-HR, WSPs are realistically preceded by MRPs, which in turn are a result of the flow around bathymetry being represented with unprecedented detail.« less

Authors:

Kurtakoti, Prajvala ^[1]; Veneziani, Milena ^[2]; Stössel, Achim ^[3]; Weijer, Wilbert ^[2]

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+ Show Author Affiliations

1. Los Alamos National Laboratory, Los Alamos, New Mexico, and Department of Oceanography, Texas A&,M University, College Station, Texas
2. Los Alamos National Laboratory, Los Alamos, New Mexico
3. Department of Oceanography, Texas A&,M University, College Station, Texas

Publication Date:

Sat Dec 01 00:00:00 EST 2018

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1482161

Alternate Identifier(s):

OSTI ID: 1483544

Report Number(s):

LA-UR-18-28028
Journal ID: ISSN 0894-8755

Grant/Contract Number:  

89233218CNA000001

Resource Type:

Published Article

Journal Name:

Journal of Climate

Additional Journal Information:

Journal Name: Journal of Climate Journal Volume: 31 Journal Issue: 23; Journal ID: ISSN 0894-8755

Publisher:

American Meteorological Society

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; Earth Sciences; Southern Ocean polynyas, ocean convection, air-sea interactions