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    This dataset presents monthly gridded sea ice and ocean parameters for the Arctic derived from the European Space Agency's satellite CryoSat-2. Parameters include sea ice freeboard, sea ice thickness, sea ice surface roughness, mean sea surface height, sea level anomaly, and geostrophic circulation. Data are provided as monthly grids with a resolution of 25 km, mapped onto the NSIDC EASE2-Grid, covering the Arctic region north of 50 degrees latitude, for all winter months (Oct-Apr) between 2010 and 2018. CryoSat-2 Level 1b Baseline C observed waveforms have been retracked using a numerical model for the SAR altimeter backscattered echo from snow-covered sea ice presented in Landy et al. (2019), which offers a sophisticated physically-based treatment of the effect of ice surface roughness on retracked ice and ocean elevations. Methods for optimizing echo model fits to observed CryoSat-2 waveforms, retracking waveforms, classifying returns, deriving sea ice freeboard, and converting to thickness are detailed in Landy et al. (In Review). This dataset contains derived sea ice thicknesses from two processing chains, the first using the conventional snow depth and density climatology from Warren et al. (1999) and the second using reanalysis and model-based snow data from SnowModel (Stroeve et al., In Review). Sea surface height and ocean topography grids were derived from only those CryoSat-2 samples classified as leads. Both the random and systematic uncertainties relevant for each parameter have been carefully estimated and are provided in the data files. NetCDF files contain detailed descriptions of each derived parameter. Funding was provided by ESA Living Planet Fellowship Arctic-SummIT grant ESA/4000125582/18/I-NS and NERC Project PRE-MELT grant NE/T000546/1.

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    The Arctic is warming more than twice as fast as the global average, making climate changess polar effects more intense than anywhere else in the world. The Arctic accounts for half of the organic carbon stored in soils. There is high confidence that the thaw of terrestrial permafrost will lead to carbon release, but only low confidence regarding timing, magnitude and relative role of CO2 versus CH4 according to the sixth assessment report of IPCC (2021). There is general consensus that these issues can be tackled through support by satellite observations, but this has not been fully exploited to date. The recently inaugurated Arctic Methane and Permafrost Challenge (AMPAC) strives to address these questions inter alia through making use of synergistic measurements, activities to improve satellite retrievals with a clear focus on high latitudes, and promoting new dedicated satellite sensors as well as improving validation of existing and upcoming satellite missions.

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    1 km Arctic regional land ice areas, daily, with cloud mask, geotiff at https://github.com/AdrienWehrle/SICE/tree/master/masks

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    Using new techniques to measure pan-Arctic sea ice thickness from the satellite radar altimeter Cryosat-2 during summer months

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  • Polar stratospheric clouds (PSCs) play a central role in the formation of the ozone hole in the Antarctic and Arctic. PSCs provide surfaces upon which heterogeneous chemical reactions take place. These reactions lead to the production of free radicals of chlorine in the stratosphere which directly destroy ozone molecules. PSCs form poleward of about 60°S latitude in the altitude range 10 km to 25 km during the winter and early spring. The clouds are classified into Types I and II according to their particle size and formation temperature. Type II clouds, also known as nacreous or mother-of-pearl clouds, are composed of ice crystals and form when temperatures are below the ice frost point (typically below -83°C). The Type I PSCs are optically much thinner than the Type II clouds, and have a formation threshold temperature 5 to 8°C above the frost point. These clouds consist mainly of hydrated droplets of nitric acid and sulphuric acid. Despite two decades of research, the climatology of PSCs is not well described, and this impacts on the accuracy of ozone depletion models. The timing and duration of PSC events, their geographic extent and vertical distributions, and their annual variability are not well understood.The Davis lidar has been used to study stratospheric clouds since 2001. The observations consist of profiles of Rayeligh laser backscatter at a wavelength of 532 nm as a function of altitude. The measurements are being used to investigate the climatology of the clouds and their relation to the temperature structure of the stratosphere, and the influence of atmospheric gravity waves and planetary waves in modulating their structure and ozone depletion.

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    Gridded product containing a spatial interpolation of the point product onto a uniform grid of elevation and uncertainty. The gridded product is published on a monthly basis with one product per region on a 2km grid in polar stereographic coordinates. The monthly product contains 3 months of data on a rolling basis each month and uses the Thematic point product as its input. For example, the January 2020 gridded product will contain point data for a window starting on 1st December 2019 and ending on 29th February 2020.

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    Launched in June 2008, Jason-2, also referred to as the Ocean Surface Topography Mission (OSTM), was the follow-on mission from Jason-1 and Posiedon/TOPEX. In this mission, the National Aeronautics and Space Administration (NASA) and Centre National d'Etudes Spatiales (CNES) worked collaboratively with the National Oceanic and Atmospheric Administration (NOAA) and European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) to extend the existing time series of ocean surface topography measurements. Jason-2 successfully obtained a continuous record of observations in line with previous missions which included measurements of time-averaged ocean circulation, global sea-level change and improved open ocean tide models, until it was decommissioned in October 2019.

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    Ice depth or thickness refers to the extent of the ice below the surface of the water. The term is also used in river and lake ice studies. Remote sensing techniques (particularly radar and microwave) have been used to estimate ice thickness as have recently declassified submarine measurements of polar ice thickness.