Due to the vast, remote and inhospitable terrain of the polar regions, it has traditionally been a difficult and resource-intensive exercise to monitor the Arctic and Antarctic. Remote sensing, via satellite missions, light aircraft and, in more recent years, drone technology and ‘in-situ’ sensors, has been a key part of how the scientific community has improved their understanding of the poles and their impact on the wider Earth system and climate.
In this article we review some of the innovative sensor technology being used by polar scientists in 2025:
Radar Altimetry
Radar altimeters measure the time taken for a radar pulse to reach and bounce back from the surface, and alongside the altitude of the sensor, we can use these measurements to estimate surface elevation. CPOM uses this technology to estimate the elevation of the Greenland and Antarctic ice sheets. Using ESA’s CryoSat-2 radar altimeter data, the CPOM-led IMBIE project monitors the impact global warming is having on these huge expanses of ice, including the volume of ice which is melting each year and how it is contributing to rising sea levels.
Video credit: ESA / Planetary Visions
Radar altimetry is an excellent tool for estimating ice freeboard for both sea ice and land ice as its signals can pass through clouds, but there are also challenges. Radar penetrates the ice sheet surface and often must be adjusted to compensate for this effect.
Laser Altimetry
LiDAR altimeters operate similarly to radar, but use laser pulses instead to capture surface elevation. Unlike radar, laser reflects from the snow surface but cannot pass through cloud cover. CPOM scientists uses data from both types of sensors, to provide more robust estimate of ice sheets. One example is a recent study by CPOM PhD Researcher, Nitin Ravinder, which showed that CryoSat-2, using radar, and ICESat-2, using LiDAR, agreed within 3% on the elevation changes of the Greenland Ice Sheet, allowing them to be combined to produce a reliable estimate of ice loss.
Optical Sensors
Sea ice is difficult to measure due to its constant movement and mix of ice floes and open water leads. CPOM researcher Amy Swiggs improves accuracy by combining radar data from CryoSat-2 with optical images from NASA’s Landsat 8 to better map sea ice in areas like the Northwest Passage. You can read more about her research on ESA’s website.
Passive microwave radiometry
The Earth naturally emits radiation which varies depending on the type of surface. Passive microwave radiometers receive this radiation and can distinguish the different radiation emitted by various surface types. CPOM scientists process and interpret the data, producing estimates of sea ice concentration or snow cover. With snow cover it is even possible to estimate the water content (slushiness) or depth of the snow. This data is highly accurate in the winter months when contrasts between water temperature and ice are larger, however in the summer when water temperatures rise and melt ponds form in the sea ice, the contrasts between the radiation is reduced, as is the accuracy of the readings.
Emerging sensor technology
One recent advancement in sensing technology that has been of particular interest to sea ice experts is ‘KuKa’ radar. This new sending technology can estimate the depth of snow on ice, which is very useful when assessing sea ice. KuKa is a dual-frequency radar operating at Ku-band (12-18 GHz) and Ka-band (30-40 GHz) frequencies, estimating the distance from the sensor to a surface in Altimeter mode, but also measuring radio backscatter in Scatterometer Mode, gaining additional information on more uneven or rough surfaces. In this research paper by Stroeve et el. this ‘Polarimetric Capability’ described helps scientists distinguish between the differing surfaces (ice, water or snow) in more detail, which is very useful when researching sea ice properties.
A Kuka used in fieldwork in Arctic Canada. Credit: Alicia Fallows (UCL)
Another key development is the introduction of sensors integrated into autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) such as drones, which can remotely collect additional data on variables such as ocean temperature and sea ice thickness in the Arctic and Antarctic. This data complements the data provided by satellite missions such as CryoSat-2 and ICESat-2. By combining this additional information with improvements in how we process this data, we can produce increasingly precise measurements without the need to visit the areas we are surveying.
Complementing the data
Each type of sensor has its strengths and weaknesses. CPOM uses data from different types of sensors to corroborate and complement each other, building an increasingly accurate picture of the cryosphere. CPOM also visits different parts of the polar regions to assess the accuracy of the data received by different sensors, such as fieldwork completed with BAS as part of the DEFIANT project.