World’s first snow satellite

World’s first snow satellite

March 5, 2009

The snow satellite CoReH2O is competing to be the European Space Agency's next Earth Explorer satellite. Norut Tromsø has been involved in the satellite's design.

It was announced on March 2 that CoReH2O is one of three Earth Explorer mission concepts to progress to the final phase of consolidation. Senior Research Scientist Eirik Malnes from Norut Tromsø is in the group of international scientists that designed the satellite.

Measuring snow and ice

As a result of global climate change, the scientific community has a major need for precise measurements of the Earth's snow and ice reserves. This covers the measurement of fresh water stored in snow on land surfaces and in snow accumulation on glaciers and ice sheets.

Measurements carried out at meteorological stations and glaciological investigations of glaciers do not provide sufficient information to develop the desired level of climate models. Consequently, the climate models do not provide a secure indication of what will happen with the snow and ice in the future.

Satellite measurements of snow and ice can provide the required information. To date no satellite has been produced for this specific purpose and, as such, the measurements have not been precise enough. However, this requirement would be covered by CoReH2O if it is chosen for launch.

From idea to launch

The process from the initial idea through to the launch of a satellite is a lengthy one. In 2005, ESA called for Earth Explorer mission ideas. Twenty candidate concepts were submitted and three years ago CoReH2O was selected as one of six to advance to the next phase.

ESA then produced a report about the six candidates and the research teams behind the proposals. On January 20-21 this year, the six candidates were presented at ESA's Earth Explorer User Consultation Meeting in Lisbon, and they were then evaluated by ESA's Earth Science Advisory Committee.

ESA's Programme Board for Earth Observation last week decided that CoReH2O was one of the final three Earth Explorer missions that will undergo feasibility studies.

"The next step is the detailed specification phase in which every part of the satellite must be described in detail," says Malnes. "After that, one of the satellites will be chosen as the next explorer mission to be launched in 2016."

Norut's contribution - models and testing

Norut wants to play an ongoing role in the development of CoReH2O. The Earth Observation Group at Norut Tromsø has for many years carried out research on the measurement of snow using satellite technology. In recent years, this group has headed several national and international snow projects.

The group has developed an operational analytical system for satellite data that is utilised by scientists, meteorologists and the power industry to be able to find the snow cover in Scandinavia in near real time. The new satellite will be a giant step forward for this work as it will also enable the amount of snow to be measured.

Norut's contribution to CoReH2O will in part involve methods to find the amount of snow. Norut also wants to equip its unmanned aerial vehicle (UAV) with equivalent radar to that planned for the satellite. This will enable the measuring methods to be tested in an affordable manner before the equipment is launched in an expensive satellite.


CoReH2O is an abbreviation for Cold Regions Hydrology High-resolution Observatory. It will be a state-of-the-art imaging radar satellite sending on two radar frequencies (9.6 and 17.2 GHz) and will measure the reflected signal from the ground/snow with two different polarisations on each frequency.

This provides four independent measurements of the snow, and is sufficient to measure the snow water equivalent or in other words the amount of water stored in the snow. Norut has contributed its competence in the areas of satellite remote sensing and understanding of how radar signals spread in different mediums (snow, ice and air), and how measurements of the radio reflections from the ground can be used to calculate the snow water equivalents on the ground under the satellite with high spatial resolution (50-100 m).

If the satellite makes it into space, these methods will be used to obtain global snow water equivalent mapsthat the climate researchers can use to improve their models and as such be able to provide more accurate descriptions of the climate in the future.

Contact person: Senior Research Scientist Eirik Malnes, tlf 934 19 461.