Predominant Sea Ice Fracture Zones Around Antarctica and Their Relation to Bathymetric Features

Abstract

Sea ice is of substantial importance for the Southern Ocean, as it insulates the relatively warm ocean from the cold atmosphere. Due to mechanical stress induced by wind and ocean currents, sea ice leads occur, which are characterized by open water and thin ice causing an increase of energy and moisture fluxes between ocean and atmosphere. Furthermore, they contribute to the ice production and provide a habitat for animals. Thus, it is important to gain information about the temporal and spatial distribution of leads on a circum‐Antarctic scale. So far, no operational data set exists, which provides such information. We use thermal satellite imagery from the Moderate Resolution Imaging Spectroradiometer to derive the predominant lead patterns for 2003–2018, April–September. This study provides first results for the long‐term average lead frequencies in the Southern Ocean and discusses possible links to ocean currents, tides, and the bathymetry.

Distribution Characteristics and Influencing Factors of Sea Ice Leads in the Weddell Sea, Antarctica

“…Along the coastal regions, there was a pronounced increase in the number and density of SILs compared to offshore areas. The distribution characteristics align with the findings of Reiser et al (2019) [34]. This observation may potentially signify a correlation between the distribution of leads and factors such as the density of WSBW, seafloor topography, and depths of the sea.…”

Patterns of wintertime Arctic sea ice leads and their relation to winds and ocean currents

“…Hence, especially in light of the observed trends in Arctic sea-ice extent (Stroeve and Notz, 2018), and with respect to the projected development of the Arctic climate system (Notz et al, 2020), the structure and dynamics of leads represent essential information for global change monitoring. While patterns in the spatial distribution of leads have recently been identified for both hemispheres with distinct spatial patterns (Reiser et al, 2019;Willmes and Heinemann, 2016) the driving mechanisms for the profound variability in wintertime sea-ice dynamics are yet to be explained (e.g. Liu et al, 2022, Arthun et al, 2019Hegyi and Taylor, 2017).…”

“…The effect of warm air intrusions, extratropical atmospheric circulation and downward infrared radiation on the overall Arctic warming and sea-ice decline have been discussed (Warner et al, 2020;Park et al, 2015;Woods and Caballero, 2016) and first insights into the role of ocean currents on predominant lead occurrences, i.e. the Antarctic Slope Current in the Southern Ocean and the Arctic Boundary Current, were given by Reiser et al, 2019 andHeinemann, 2016, respectively. In this paper we will first give an overview of the used data (Ch. 1) and then identify regions where leads are forming most frequently using a novel sea-ice lead climatology (Ch.…”

A New Algorithm for Daily Sea Ice Lead Identification in the Arctic and Antarctic Winter from Thermal-Infrared Satellite Imagery

“…Several hot spots where sea ice leads are predominantly present can be identified, for example, the Beaufort Gyre, Greenland Sea, and Barents Sea (Arctic) and the Weddell Sea and Ross Sea (Antarctic). Similar to the studies by Reference [24] for the Arctic and Reference [33] for the Antarctic, we calculated the long-term average lead frequency based on the filtered data (Figure 10), which reveals persistent lead locations in both hemispheres with respect to lead occurrences, where frequencies of 0.4 (Arctic) and 0.2 (Antarctic) are exceeded in several regions, for example, along the continental shelf break and bathymetric features in the deep sea. Compared with the long-term average of potential leads in the Antarctic as shown in Reference [33] (Figure 1), the filtered lead frequencies are lower due to the application of the FCAF, which removes artefacts from the potential lead maps.…”