Mapping Arctic Bottomfast Sea Ice Using SAR Interferometry

Dyre Dammann,Leif Eriksson,Christopher Stevens,Andrew Mahoney,Craig Tweedie,Joost Van Der Sanden,Franz Meyer,Hajo Eicken

doi:10.3390/rs10050720

Abstract

Bottomfast sea ice is an integral part of many near-coastal Arctic ecosystems with implications for subsea permafrost, coastal stability and morphology. Bottomfast sea ice is also of great relevance to over-ice travel by coastal communities, industrial ice roads, and marine habitats. There are currently large uncertainties around where and how much bottomfast ice is present in the Arctic due to the lack of effective approaches for detecting bottomfast sea ice on large spatial scales. Here, we suggest a robust method capable of detecting bottomfast sea ice using spaceborne synthetic aperture radar interferometry. This approach is used to discriminate between slowly deforming floating ice and completely stationary bottomfast ice based on the interferometric phase. We validate the approach over freshwater ice in the Mackenzie Delta, Canada, and over sea ice in the Colville Delta and Elson Lagoon, Alaska. For these areas, bottomfast ice, as interpreted from the interferometric phase, shows high correlation with local bathymetry and in-situ ice auger and ground penetrating radar measurements. The technique is further used to track the seasonal evolution of bottomfast ice in the Kasegaluk Lagoon, Alaska, by identifying freeze-up progression and areas of liquid water throughout winter.

Highlights

The proposed approach is first demonstrated in the Mackenzie Delta using in-situ ice auger and ground penetrating radar (GPR) measurements for validation (Section 3.1), near the Colville Delta using bathymetry (Section 3.2), and in Elson Lagoon using Landsat 8 and high-resolution bathymetry data (Section 3.3)
Bottomfast ice can be identified as low-backscatter regions in PALSAR backscatter images with radar energy penetrating into the seafloor in the absence of an ice/water interface (Figure 3a)
The approach was successfully validated in fresh water near the Mackenzie Delta featuring low phase values and high coherence in areas of bottomfast ice confirmed using ground penetrating radar (GPR) and auger measurements

Summary

Introduction

Evolution and Relevance of Bottomfast Sea Ice. Arctic sea ice is a key component of the earth’s climate system. Arctic sea ice is a key component of the earth’s climate system It regulates absorbed solar radiation during summer and heat loss from the ocean in winter. The landfast ice, a strip of ice anchored in place along the Arctic coastlines, is significant and serves as an extension of the land for part of the year. It is used for denning by seals, migratory routes by caribou, and hunting of marine mammals by coastal populations [1].

Methods

Results

Discussion

Conclusion