Sea Ice Freeboard in the Ross Sea from Airborne Altimetry IcePod 2016–2017 and a Comparison with IceBridge 2013 and ICESat 2003–2008

Liuxi Tian,Stephen F Ackley,Alberto M Mestas-Nuñez,Kirsty J Tinto,Christopher J Zappa,Robin E Bell,Yongli Gao,Hongjie Xie

doi:10.3390/rs12142226

Liuxi Tian, Stephen F Ackley + Show 6 more

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https://doi.org/10.3390/rs12142226

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Abstract

As part of the Polynyas and Ice Production in the Ross Sea (PIPERS) project, the IcePod system onboard the LC-130 aircraft based at McMurdo Station was flown over the Ross Sea, Antarctica in November 2016 and 2017, with the purpose of repeating the same lines that NASA’s Operation IceBridge (OIB) aircraft flew over in 2013. We resampled the lidar data into 70 m pixels (similar to the footprint size of OIB L2 and ICESat data) and took the mean of the lowest 2% elevation values of 25 km (50 km) length along a flight track as the local sea level of the central 25 km (50 km). Most of the IcePod data were over the same flight lines taken by OIB in 2013, so the total freeboard changes from 2013 to 2016 and 2017 were examined. Combining with the ICESat (2003–2008), we obtained a better picture of total freeboard and its interannual variability in the Ross Sea. The pattern of the sea ice distribution supports that new ice produced in coastal polynyas was transported northward by katabatic winds off the ice shelf. Compared to ICESat years, sea ice near the coast was thicker, while sea ice offshore was thinner in the more recent OIB/IcePod years. The results also showed that, in general, sea ice was thicker in 2017 compared to 2013 or 2016—0.02–0.55 m thicker in total freeboard.

Highlights

Sea ice in the polar regions plays a critical part in climate change because of its impact and feedback on the transfer of energy across the ocean–atmosphere interface [1,2]
Knowing the interannual variability of the sea ice thickness in the Ross Sea is crucial to the estimation of sea ice production and better knowledge of the energy exchange between ocean and atmosphere as well as improvement of model prediction [9]
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Summary

Introduction

Sea ice in the polar regions plays a critical part in climate change because of its impact and feedback on the transfer of energy across the ocean–atmosphere interface [1,2]. Without knowing the changes in the sea ice thickness over the Ross Sea, it is hard to evaluate how sea ice cover is responding to a changing climate in this region. There are three polynyas—Ross Ice Shelf polynya (RISP), Terra Nova Bay polynya (TNB), and McMurdo Sound polynya (MCM)—in the Ross Sea. There are three polynyas—Ross Ice Shelf polynya (RISP), Terra Nova Bay polynya (TNB), and McMurdo Sound polynya (MCM)—in the Ross Sea These polynyas are the high rates of sea ice production areas, as older sea ice is continually blown offshore and replaced by newly formed ice [8]. This causes dense water formation by brine rejection and thereby contributes to the formation of Antarctic bottom water (AABW). Knowing the interannual variability of the sea ice thickness in the Ross Sea is crucial to the estimation of sea ice production and better knowledge of the energy exchange between ocean and atmosphere as well as improvement of model prediction [9]

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