On the Generation of Weddell Sea Polynyas in a High-Resolution Earth System Model

Abstract

Larger Weddell Sea polynyas (WSPs), differentiated in this study from the smaller Maud Rise Polynyas (MRPs), forming to the east of the prime meridian in the proximity of the Maud Rise seamount, have last been observed in the 1970s. We investigate WSPs that grow realistically out of MRPs in a high-resolution (HR) preindustrial simulation with the Energy Exascale Earth System Model version 0.1. The formation of MRPs requires HR to simulate the detailed flow around Maud Rise, while the realistic formation of WSPs requires a model to produce MRPs. Furthermore, WSPs tend to follow periods of a prolonged build-up of a heat reservoir at depth and weakly negative wind-stress curl in association with the core of the southern hemisphere westerlies at an anomalously northern position. While this scenario also leads to drier conditions over the central Weddell Sea, which some literature claims to be a necessary condition for the formation of WSPs, our model results indicate that open-ocean polynyas do not occur during periods of weakly negative wind-stress curl despite drier atmospheric conditions. Our study supports the hypothesis noted in earlier studies that a shift from a weakly negative to a strongly negative wind-stress curl over the Weddell Sea is a prerequisite for WSPs to form, together with a large heat reservoir at depth. However, the ultimate trigger is a pronounced MRP; whose associated convection creates high surface salinity anomalies that propagate westward with the flow of the Weddell Gyre. If large enough, these anomalies trigger the formation of a WSP and a pulse of newly formed Antarctic Bottom Water.

Application of Road Extraction from High-Resolution Remote Sensing Images in Tourism Navigation and GIS

“…(4) Context Characteristics. It is the image feature information of the areas closely related to the road, such as the roadside trees and buildings on both sides of the road, the lane, zebra crossing, and various driving signs on the road on the high-resolution image, as well as the material properties of the road, which are all the context information of the road [15].…”

On the Intermittent Occurrence of Open‐Ocean Polynyas in a Multi‐Century High‐Resolution Preindustrial Earth System Model Simulation

“…Based on the results from a multidecadal high‐resolution Earth System Model (ESM) simulation to be described later, and previous work by Kurtakoti et al. (2018, 2021), we distinguish the following open‐ocean polynyas: Maud Rise Polynya (MRP, Figure 1a), Astrid Ridge Polynya (ARP, Figure 1b), and Weddell Sea Polynya (WSP, Figure 1c). While somewhat arbitrary, we follow Kurtakoti et al.…”

“…In the Weddell Sea, open-ocean polynyas form usually at distinct locations that are preconditioned by weak stratification and are thus prone to deep convection. Based on the results from a multidecadal high-resolution Earth System Model (ESM) simulation to be described later, and previous work by Kurtakoti et al (2018Kurtakoti et al ( , 2021, we distinguish the following open-ocean polynyas: Maud Rise Polynya (MRP, Figure 1a), Astrid Ridge Polynya (ARP, Figure 1b), and Weddell Sea Polynya (WSP, Figure 1c). While somewhat…”

Ocean Convection

“…These smaller polynyas are likely tied to the bathymetric features of Maud Rise, which has a water column depth of less than 2000 m and can support Taylor column activity [119]. The smaller polynyas near Maud Rise may be a prerequisite to the formation of the larger Weddell Sea polynya seen in the 1970s [120].…”