We evaluate polarimetry for snow depth retrieval on Arctic winter transport routes. Over landfast ice and tundra, traditional dual-frequency (Ku/Ka) methods often fail. We demonstrate that cross-polarization (VH) provides a more reliable marker for snow/ice and snow/ground interfaces. For lakes, we successfully resolve air, snow, and ice interfaces to retrieve snow and ice thickness simultaneously. These results establish a baseline for future polarimetric satellite missions.

In this study, we use three satellites to test the planned remote sensing approach of the upcoming mission Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) over sea ice and that its dual radars will accurately measure the heights of the top and base of snow sitting atop floating sea ice floes. Our results suggest that CRISTAL's dual radars will not necessarily measure the snow top and base under all conditions. We find that accurate height measurements depend more on surface roughness than on snow properties, as is commonly assumed.

Understanding snow depth on sea ice is key for measuring ice thickness, studying ecosystems, and modeling climate. Using snow and ice thickness measurements from Arctic and Antarctic campaigns, this study examines sub-kilometer-scale (<1  km²) snow depth variations and identifies the most suitable statistical models for different ice ages, thicknesses, and weather conditions. These results can improve sub-grid snow parameterizations in snow models and remote sensing algorithms.

The Arctic is warming several times faster than the rest of the planet. Here, we use climate model projections to quantify for the first time how this faster warming in the Arctic impacts the timing of crossing the 1.5 °C and 2 °C thresholds defined in the Paris Agreement. We show that under plausible emissions scenarios that fail to meet the Paris 1.5 °C target, a hypothetical world without faster warming in the Arctic would breach that 1.5 °C target around 5 years later.

We show that wind redistributes snow on Arctic sea ice, and Ka- and Ku-band radar measurements detect both newly deposited snow and buried snow layers that can affect the accuracy of snow depth estimates on sea ice. Radar, laser, meteorological, and snow data were collected during the MOSAiC expedition. With frequent occurrence of storms in the Arctic, our results show that wind-redistributed snow needs to be accounted for to improve snow depth estimates on sea ice from satellite radars.