OBSERVER: New Copernicus Land Monitoring Services: Launch of the second part of the High Resolution Snow and Ice Monitoring Products

OBSERVER: New Copernicus Land Monitoring Services: Launch of the second part of the High Resolution Snow and Ice Monitoring Products

OBSERVER: New Copernicus Land Monitoring Services: Launch of the second part of the High Resolution Snow and Ice Monitoring Products

Thu, 13/01/2022 – 11:53


Snow and ice play a vital role in the Earth’s climate system, energy budget and radiation balance. They are also the major drivers of water cycles in high latitudes and mountains. Rapid declines in spring snow cover extent and snow cover duration are distinct indicators of global climate change which is why the monitoring of snow and ice is an increasingly important activity.

In acknowledgement of this importance, the Copernicus Land Monitoring Service (CLMS) is releasing the second part of its near real-time, High Resolution Snow and Ice (HR-S&I) Monitoring products. These products specifically address snowmelt information based on Sentinel-1 satellite radar imagery, and complement the already operationally processed snow and ice cover information based on the Sentinel-2 satellite optical imagery. Together these products create a comprehensive set of high-resolution information on snow and ice properties that is able to encourage the development of new applications and support decision-making.


The new High Resolution Snow and Ice (HR-S&I) Monitoring products

The Pan European Component of the Copernicus Land Monitoring Service (CLMS) is coordinated by the European Environment Agency (EEA) and has been implementing a set of High Resolution Biophysical Parameter products addressing the land cryosphere since 2018. The Pan European component provides a highly detailed close-up view of the regional snow conditions up to a 20-metre spatial resolution with optical, and a 60-metre spatial resolution with radar-based observations. The high resolution products are complemented with the Copernicus Global Land Service, which offers snow and ice information on a coarser resolution but covers the whole Northern Hemisphere. The Global Land Service products include daily areal snow extent with a 500-metre spatial resolution for Pan European domain and 1-kilometre resolution for the Northern Hemisphere. The daily Snow Water Equivalent product is provided with a 5-kilometre spatial resolution while the Lake Ice Extent products are available for Northern Europe with a 250-metre resolution and a 500-metre resolution for the Northern Hemisphere. Altogether, the Copernicus Land Monitoring Service products provide a comprehensive view of our cryosphere in multiple scales from local to a global context.


Why do we need snow and ice monitoring from satellites?

Radiation balance estimates are highly influenced by snow and ice induced changes in Earth’s surface albedo (the proportion of the incident light or radiation that is reflected by a surface). In order to obtain the best possible understanding of both the current and future state of Earth’s climate, detailed and reliable information on snow and ice are of paramount importance.

The new near real-time satellite-based products offer large scale, spatially highly detailed, and temporally consistent information of the terrestrial cryosphere.  Assimilation of such remote sensing datasets can help atmospheric, climate and hydrological models to improve their accuracy.

Satellite-based snow and ice monitoring also have an ever-increasing significance for commercial purposes. For example, high resolution, quality-controlled and near real-time satellite-based data products derived from snow and ice conditions are often used in general-purpose consumer applications focusing on daily situational awareness, recreation, and various business activities.

The Alpine region in Central Europe, with approximately 13 million inhabitants, is one of the most densely populated mountain areas in the world and one of the largest mountainous regions in Europe. The Alps are an important freshwater reservoir in Central Europe and act as a magnet for a powerful tourism sector, particularly during the winter season. The Alpine Convention (an international territorial treaty for the sustainable development of the Alps) with the European Union and its member states has emphasised the importance of supporting and leveraging sustainable alpine development and management to maintain and protect nature, ecosystems, and wildlife. Satellite-based monitoring of snow and ice conditions (such as what is this new product provides) for water management activities, natural hazard mitigation and sustainable tourism can address those requirements for both end-users and stakeholders.


Copernicus’ role in European terrestrial cryosphere monitoring

The cryosphere is an all-encompassing term for those portions of Earth’s surface where water is in its solid form, frozen into ice or snow. The latest reports from the IPCC (Intergovernmental Panel on Climate Change), “AR6 Climate Change 2021: The Physical Science Basis1” and Special Report on Ocean, and Cryosphere in a Changing Climate (SROCC)2” highlight the importance of a better understanding of the cryosphere and high mountain areas. Changing climate and impacts on the cryosphere bring new challenges to local communities and society. The increasing frequency of hazards such as avalanches, landslides, and flooding are endangering local communities. Exceptionally short or long winter seasons are affecting business sectors like tourism and agriculture, respectively. Adequate monitoring helps for understanding, adapting, and responding to those and helps to develop sustainable and resilient risk management strategies. The Copernicus Climate Change Service (C3S) and the Copernicus Land Monitoring Service (CLMS) together provide an extensive portfolio of products for terrestrial cryosphere monitoring. The newly released HR-S&I products, complemented by the Northern Hemisphere-wide snow and ice maps from the CLMS Global Land Service support cold climate societies and will also improve decision-making processes through increased accuracy achieved with observations from regional to global scales in varying resolutions.

Credit: M.Kosmale


Sentinel satellites as European contribution to cryosphere monitoring – where does the data come from?

The Polar-orbiting Sentinel-1 and Sentinel-2 satellites of Copernicus provide the base for high-resolution monitoring of the earth’s land surface conditions. Sentinel-1, with its C-band synthetic aperture radar (SAR), allows the acquisition of imagery in all weather conditions. The Sentinel-2 with its optical MultiSpectral Imaging sensor (MSI) offers systematic global acquisitions of high-resolution, multispectral images allied to a high revisit frequency.

The spatial resolution of the Sentinel satellites depends on wavelength and imaging mode applied and varies with pixel sizes between 10-metres and 60-metres. Their complementary capabilities (optical & microwave radar) make them an excellent fit for a wide range of downstream services in the cryosphere domain, such as in the sector of hydropower management, tourism, transport, natural hazard monitoring as well as supporting local decision making.


Snow monitoring service

Snow stores a significant mass of water and with its highly dynamic states and has a strong effect on regional and global energy and water cycles. Snow cover extent is an important parameter for hydrological modelling and for predicting natural hazards such as flood events. Snow cover is specified as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS).

You can find a short introduction on how snow and ice extent are monitored with the help of Sentinel data:


HR-S&I Product details

Two of the HR-S&I products describe the percentage of the pixel area covered by snow, the near real-time processed Fractional Snow Cover (FSC) and the daily Cumulative Gap-filled Fractional Snow Cover (GFSC).

Fractional Snow Cover is differentiated into snow presence at the top of the canopy (FSC-TOC), which means above tree level, as well as on the ground (FSC-OG). Both products are available at a spatial resolution of 20 x 20-metres and are derived from Sentinel-2 data, and therefore available in cloud-free conditions.

The snow state (wet or dry snow) is retrieved from Sentinel-1 SAR observations. The Wet and Dry Snow (WDS) product provides information on snow state, based on a combination of optical and microwave measurements. For high-mountain areas, the SAR Wet Snow (SWS) product provides snow state information for every Sentinel-1 overpass, whereas the WDS is retrieved also outside mountains for cloud-free Sentinel-2 observations. These Sentinel-1 and Sentinel-2 based datasets provide a comprehensive picture of snow conditions in the Pan European area.

A further derived product, building on the FSC, WDS and SWS is the daily Cumulative Gap-filled Fractional Snow Cover (GFSC), which consists of spatial gap-filling and temporal compositing to complete the picture of current snow conditions. It is based on available wet snow products (WDS and SWS) to fill existing gaps in mountainous parts of the optical FSC product. Such gaps occur due to clouds or a lack of sensor coverage. Temporal gap-filling uses the recent historical FSC,WDS and SWS data to fill any information gaps in the observations available for the current day. This product is produced at a 60 x 60-metre resolution. Gap-filling offers a more complete picture of the snow state for selected regions and the development of dedicated snow applications.

For long-term monitoring of climatological snow information, the Persistent Snow Area (PSA) is generated on a yearly basis. Based on FSC, it provides information on areas that are covered by snow throughout the entire year. It is available on an annual basis at the end of each hydrological year, with a resolution of 20 x 20-metres.

All these new datasets on snow provide valuable information for monitoring changes in the cryosphere, which are particularly relevant for sensitive and vulnerable snow-dependent ecosystems, and communities in mountainous areas.


River and Lake Ice products

Like snow, lake ice is an important climate indicator and a key parameter in hydrological modelling and weather forecasting. After integrating the information over time, the comparison of interannual ice freeze-up allows access to important climatological parameters. Ice formation in lakes and rivers have a further significant effect on river discharge and can contribute to or induce localised flooding. Changes in the amount and seasonality of runoff in river basins directly impact local water resources and agriculture. Long-term ground-based in-situ monitoring of river and lake ice has been conducted for decades but can only provide spatially very restricted point information. Remote sensing, on the other hand, offers the opportunity of continuous monitoring for spatially extensive areas, dictated by the satellite’s orbit, revisit frequency and its sensor’s field of view. High spatial resolutions up to several metres in pixel size can further be used to resolve small scale features for river and lake basins. The HR-S&I service is addressing these issues with its new River and Lake Ice products.

The River and Lake Ice Extent (RLIE) provides pixel-based information about snow-free or snow-covered ice presence on the hydrographic network. Three products are available, depending on their data source: Sentinel-1 SAR, Sentinel-2 MSI and the combination of both. All RLIE products have a spatial resolution of 20 metres.

The pixel-based information is also aggregated to summary statistics in the Aggregated River and Lake Ice Extent (ARLIE), which informs about the presence of snow-free or snow-covered ice, open water and other soil features like vegetation and bare soil on 10-kilometre river sections and lakes predefined by the EU-Hydro database within the EEA39 countries. While all RLIE are available in near real-time, the aggregated product is updated monthly supporting long-term seasonal monitoring.



The new high resolution snow and ice products, with up to 20 metre spatial resolution for snow, river, and lake ice, provide a wealth of opportunities for a wide range of new applications and information services. The routinely produced datasets are quality controlled and accessible in near real-time providing a basis for the development of tailored applications and further downstream services; e.g., in the sectors of hydropower management, tourism, transport, as well as supporting local decision making.


The official launch event of the Copernicus Land Monitoring Service’s new High Resolution Snow and Ice Monitoring Service (HR-S&I) takes place on the 10th of March 2022.


Registration and product updates are available at:…


The new consistent and quality-controlled HR S&I products on ice and snow are available from WEkEO:


Product Information

Under the coordination of the European Environment Agency (EEA) within the Copernicus framework, established remote sensing experts of this European consortium are responsible for research, development, and processing of all HR-S&I products:


Magellium, CESBIO, ENVEO, Astri Polska, Meteo France, Finnish Meteorological Institute.




1 IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press. In Press.


2 Hock, R., G. Rasul, C. Adler, B. Cáceres, S. Gruber, Y. Hirabayashi, M. Jackson, A. Kääb, S. Kang, S. Kutuzov, A. Milner, U. Molau, S. Morin, B. Orlove, and H. Steltzer, 2019: High Mountain Areas. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]

Thu, 13/01/2022 – 12:00

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