Making inference about the state of the Antarctic and Greenland Ice Sheets with the production of swath elevations, DEMs, elevation change and innovative science products making use of the technique of swath interferometry applied to SARIn mode CryoSat data.

The study aimed at exploring, developing and validating different approaches to retrieve snow thickness over sea ice; to develop a new prototype processor; and to produce and validate an experimental dataset of snow thickness over the Arctic.

Climate change is one of the greatest societal challenges of the 21st century. The dominant source of global warming is the increase of anthropogenic greenhouse gases in the Earth`s atmosphere. atmosphere. The two most important of those species are carbon dioxide (CO2) and methane (CH4). Together they account for ~82% of the anthropogenic radiative forcing. However, uncertainties in our knowledge of the budgets of these gases, which are determined by their sources and sinks, as well as inadequately understood feedback mechanisms, limit the accuracy of current climate change projections from the local to the global scale. To reliably predict the climate of our planet, and to guide political conventions on greenhouse gas avoidance, adequate knowledge of the sources and sinks of these greenhouse gases, their feedbacks, and the quantification of natural versus anthropogenic fluxes is mandatory. Wetland emissions of methane constitute the largest single source of methane to the atmosphere, even when considering all anthropogenic emissions, and are the most uncertain part of the budget. After the tropics, the largest distribution of wetlands is in the Arctic. The Arctic is warming twice as fast as compared to the global average, making climate changess polar effects more intense than anywhere else in the world. The Arctic accounts for nearly 50% of all organic carbon stored in the planetss soil but rising temperatures and thawing permafrost threatens its stability. The main objectives and tasks of MethaneCAMP are to: Collaborate and coordinate with the AMPAC (Artic Methane and Permafrost Challenge) initiative and forming AMPAC network aiming to contribute to bottom:up and top-down estimates of changes in methane emissions in the Arctic. Prepare a high-latitude-focused assessment of current atmospheric CH4 retrievals from medium spatial resolution and high spatial resolution instruments. Identify the improvement potential for high-latitude retrievals of CH4, test and validate these improvements and synthesize the potential of joint strategies. Analyse the changes in the Arctic CH4 with specific focus on i) quantifying longer:term trends, ii) identifying hot spots directly from observations, and iii) studying the apportionment between biogenic and anthropogenic CH4 sources by employing multi-scale Arctic CH4 observations in inverse modelling.

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.

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.

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.

Sea Surface Salinity (SSS) is a key indicator of the freshwater fluxes and an important variable to understand the changes the Arctic is facing. However, salinity in-situ measurements are very sparse in the Arctic region. For this reason, remote sensing salinity measurements (currently provided by L-band radiometry satellites, SMOS and SMAP) are of special relevance for this region. The retrieval of SSS in the Arctic represents a challenge, because brightness temperatures measured by L-band satellites are less sensitive to salinity in cold waters. An additional drawback consists in the presence of sea ice, that contaminates the brightness temperature and must be adequately processed. The ESA Arctic+ Salinity project (Dec 2018 – June 2020) will contribute to reduce the knowledge gap in the characterization of the freshwater flux changes in the Arctic region.

Quantitative multi-scale (temporal and spatial) understanding of sea ice, ocean and atmosphere interactive processes and their mutual feedback, focusing on four Arctic Scientific research Challenges- Arctic Amplification, open water on sea ice dynamics, impact of extreme event storms in sea-ice formation, Artcic ocean spin up

Arctide2017 is a high-resolution tidal atlas of the Arctic Ocean. Developed by NOVELTIS, DTU Space and LEGOS, it combines altimeter data from ESA's Envisat and CryoSat satellites into the most complete dataset used in the Arctic region to estimate tidal information

1 km Greenland, daily, with cloud mask, geotiff at https://github.com/AdrienWehrle/SICE/tree/master/masks