Inside Katabatic Winds Over the Terra Nova Bay Polynya: 2. Dynamic and Thermodynamic Analyses

Abstract

Antarctic coastal polynyas (ACPs) occur where air is funneled into valleys and ejected horizontally over adjacent ocean regions, pushing any newly formed sea ice away from the coast. During cold seasons, the exposure of the relatively warm ocean surfaces to the sometimes hurricane-force winds causes great amounts of enthalpy (sensible and latent heat energy) to be lost from the surface of the polynyas, resulting in sea ice formation (e.g., Gordon & Comiso, 1988;Z. Zhang et al., 2015), and brine rejection (Mathiot et al., 2012) which can lead to the creation of deep ocean water masses that circulate throughout the world ocean (Orsi & Wiederwohl, 2009;Rusciano et al., 2013). Although the surface areas of ACPs are relatively small (e.g., Bromwich & Kurtz, 1984), their potential impacts on regional and global climate are significant due to the large amounts of sea ice and dense water that are created within them (Fusco et al., 2009;Gordon, 2001) and the injection of heat and moisture into the atmosphere (Renfrew, 2002).Due to their small size, ACPs are not resolvable by the general circulation models (GCMs) that are used to understand and predict future climate change. Therefore, to quantify the potential impacts of ACPs on global climate and regional ice production, their enthalpy loss and related effects must be simulated using sub-grid scale parameterizations. Typically, these parameterizations of surface fluxes are based on bulk

Inside Katabatic Winds Over the Terra Nova Bay Polynya: 1. Atmospheric Jet and Surface Conditions

“…The purpose of this paper is to describe the rarely sampled internal characteristics of the state variables (wind vector, temperature, humidity) within a katabatic wind event and how these variables evolve downwind in response to surface conditions. A companion paper (Guest, 2021) builds on the material presented in this paper and uses the same data to perform a dynamic and thermodynamic analysis of the katabatic wind event and will be referred to as “Part 2”. This paper, “Part 1”, is arranged as follows: after this introduction (Section 1) is an overview and measurement strategy (Section 2), measurement description (Section 3), results (Section 4), and conclusions and comparisons (Section 5).…”

Sea ice formation, glacial melt and the solubility pump boundary conditions in the Ross Sea

“…While we assert that there are several lines of physical evidence to support a suppression in air bubble injection, it is worth recalling that we noted two other PIPERS studies in Section 2.3m that suggest sea spray production by wave tearing may have been important to air-sea heat flux (Guest 2021) and ice production. These are the sort of conditions often associated with air bubble injection, which appears to contradict our results.…”

“…However, these algorithms have been modified to detect frazil ice formation and this change has significantly increased the estimates of annual ice production to greater than 20 m/yr, including in Terra Nova Bay (Nakata et al 2021). Last, we note that two PIPERS-related studies of Terra Nova Bay polynya have invoked the potential for sea spray to enhance heat loss (Guest 2021) and sea ice production, perhaps by as much as 40%…”

Spatial characteristics of frazil streaks in the Terra Nova Bay Polynya from high-resolution visible satellite imagery

“…The goal was to find values of s necessary to reproduce the observed 535 Lp(X) curves. For the large polynyas with extent exceeding 40 km, s as low as 25-30 km were needed, several times lower than the e-folding length scales known from observations during polynya events over TNB, exceeding 100 km and in some cases as large as 190 km (Guest, 2021b). With s > 100 km, ratios of Lp/Lp,OW are never lower than ~80 %.…”

“…The existing estimates of these quantities (e.g., Nakata et al, 2021 and references there) are based on low-resolution satellite products, from which no information on the open-water and frazil/grease-ice-covered surface can be obtained, crucial for heat flux computation (Guest. 2021b, Ackley et al, 2022.…”