Abstract
Abstract. To improve our understanding of how snow properties influence sea ice thickness retrievals from presently operational and upcoming satellite radar altimeter missions, as well as to investigate the potential for combining dual frequencies to simultaneously map snow depth and sea ice thickness, a new, surface-based, fully polarimetric Ku- and Ka-band radar (KuKa radar) was built and deployed during the 2019–2020 year-long MOSAiC international Arctic drift expedition. This instrument, built to operate both as an altimeter (stare mode) and as a scatterometer (scan mode), provided the first in situ Ku- and Ka-band dual-frequency radar observations from autumn freeze-up through midwinter and covering newly formed ice in leads and first-year and second-year ice floes. Data gathered in the altimeter mode will be used to investigate the potential for estimating snow depth as the difference between dominant radar scattering horizons in the Ka- and Ku-band data. In the scatterometer mode, the Ku- and Ka-band radars operated under a wide range of azimuth and incidence angles, continuously assessing changes in the polarimetric radar backscatter and derived polarimetric parameters, as snow properties varied under varying atmospheric conditions. These observations allow for characterizing radar backscatter responses to changes in atmospheric and surface geophysical conditions. In this paper, we describe the KuKa radar, illustrate examples of its data and demonstrate their potential for these investigations.
Highlights
Sea ice is an important indicator of climate change, playing a fundamental role in the Arctic energy and freshwater balance
The Ku-band signals exhibit strong backscatter from greater ranges, which could correspond to volume scattering in the snow, layers with different dielectric properties caused by density inhomogeneities and/or the snow–sea ice interface
If the radar introduces no distortions, there will be a first sidelobe at a level of −32 dBc and a second sidelobe at a level of −42 dBc
Summary
Sea ice is an important indicator of climate change, playing a fundamental role in the Arctic energy and freshwater balance. Over the last several decades of continuous observations from multifrequency satellite passive microwave imagers, there has been a nearly 50 % decline in Arctic sea ice extent at the time of the annual summer minimum (Stroeve and Notz, 2018; Stroeve et al, 2012; Parkinson and Cavalieri, 2002; Cavalieri et al, 1999). This loss of sea ice area has been accompanied by a transition from an Arctic Ocean dominated by older and thicker multiyear ice (MYI) to one dominated by younger and thinner first-year ice (FYI; Maslanik et al, 2007, 2011). Accurate ice thickness monitoring is essential for heat and momentum budgets, ocean properties, and the timing of sea ice algae and phytoplankton blooms (Bluhm et al, 2017; Mundy et al, 2014)
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