Spatiotemporal Analysis of Sea Ice Leads in the Arctic Ocean Retrieved from IceBridge Laxon Line Data 2012–2018

Dexuan Sha,Hai Lan,Alberto M Mestas-Nuñez,Younghyun Koo,Shorojit Biswas,Hongjie Xie,Qian Liu,Anusha Srirenganathan,Chaowei Yang,Xin Miao

doi:10.3390/rs13204177

Abstract

The ocean and atmosphere exert stresses on sea ice that create elongated cracks and leads which dominate the vertical exchange of energy, especially in cold seasons, despite covering only a small fraction of the surface. Motivated by the need of a spatiotemporal analysis of sea ice lead distribution, a practical workflow was developed to classify the high spatial resolution aerial images DMS (Digital Mapping System) along the Laxon Line in the NASA IceBridge Mission. Four sea ice types (thick ice, thin ice, open water, and shadow) were identified, and relevant sea ice lead parameters were derived for the period of 2012–2018. The spatiotemporal variations of lead fraction along the Laxon Line were verified by ATM (Airborne Topographic Mapper) surface height data and correlated with coarse spatial resolution sea ice motion, air temperature, and wind data through multiple regression models. We found that the freeboard data derived from sea ice leads were compatible with other products. The temperature and ice motion vorticity were the leading factors of the formation of sea ice leads, followed by wind vorticity and kinetic moments of ice motion.

Highlights

Arctic sea ice functions as a sensitive indicator of global warming because sea ice responds to even a small increase in temperature [1,2,3]
This paper focuses on the spatiotemporal analysis of sea ice lead distribution through NASA’s Operation IceBridge images, which used a systematic sampling scheme to collect high spatial resolution DMS aerial photos along critical flight lines in the Arctic
Four sea ice classes were defined: (1) thick ice is usually thick ice or snow-covered ice with a high albedo; (2) thin ice is usually fresh and newly formed ice, which has a smooth surface with a low albedo, since solar radiation is partially absorbed by the water beneath it; (3) open water is dark and smooth due to its strong absorbance of solar radiation; and (4) shadow is within a thick-ice area and is a relative dark feature projecting on the ice surface by surrounding ridges or snow dunes

Summary

Introduction

Arctic sea ice functions as a sensitive indicator of global warming because sea ice responds to even a small increase in temperature [1,2,3]. This is due to how sea ice has a significantly higher albedo compared to that of the water surface. When the Arctic sea ice starts to melt, the oceans absorb more solar radiation and warm up, accelerating the melting of sea ice in a positive feedback [4]. Since a lead is physically an open water body, thin ice, or mixed open water and thin ice within (thicker) sea ice floe or between sea ice floes, it allows the direct interaction between the atmosphere and the ocean and is the only (or major) channel in the cold Arctic

Methods

Findings

Discussion

Conclusion