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

• Published in: Geophysical Research Letters
• Main Authors: Reiser, F., Willmes, S., Hausmann, Ute, Heinemann, G.
• Other Authors: Universität Trier, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), European Project: 637770,H2020,ERC-2014-STG,WAPITI(2015)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: MODIS; Antarctic sea ice leads; bathymetry; tides; ocean currents; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Antarctic; Southern Ocean; The Antarctic; Antarc*; Antarctica; Sea ice
• Online Access: https://hal.sorbonne-universite.fr/hal-02402416; https://hal.sorbonne-universite.fr/hal-02402416/document; https://hal.sorbonne-universite.fr/hal-02402416/file/Reiser_et_al-2019-Geophysical_Research_Letters.pdf; https://doi.org/10.1029/2019GL084624

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. Plain Language Summary The polar regions are strongly influenced by sea ice, which covers large areas of the ocean's surface. Interacting with the atmosphere and the ocean, sea ice is a very dynamic surface with a large temporal and spatial variability. Under the forcing of winds and ocean currents, sea ice is subject to deformation processes causing cracks (leads) in the ice. The observation of these leads is the aim of this study since they are an important feature. For instance, open water can be found in these cracks, which enables the warm ocean (−1.7 • C) to lose energy to the cold atmosphere. Also, sea ice forms a habitat for animals. In this study, the focus is on the Southern Hemisphere where sea ice surrounds the Antarctic continent. For the winter months, we use thermal infrared satellite images where leads appear as warm, almost linear features compared to the cold ice cover. By using computer algorithms, the cracks are detected automatically. This is the first study that shows these features in the Southern Ocean. Leads not only exist close to the coastline ...