Sea Ice Remote Sensing

Map of Arctic sea ice thickness (April 2015) obtained from CryoSat-2 data
Map of Arctic sea ice thickness (April 2015) obtained from CryoSat-2 data (Graphic: AWI, Sea Ice Physics)

The inaccessibility and sheer size of sea ice covered regions in the Arctic and Antarctic oceans make satellite remote sensing the only tool that is able to obtain a full picture of sea ice conditions. The Sea Ice Physics section is actively involved in the development and validation of sea-ice thickness retrieval algorithms for satellite radar altimetry. The CryoSat-2 mission of the European Space Agency (ESA) is based on a radar altimeter that fully maps Antarctic sea ice and Arctic sea ice up to a latitude of 88°N. This coverage is unparalleled in comparison with all previous and existing satellite altimeters which makes CryoSat-2 an ideal tool for observing sea ice thickness from space.

The measuring principle is based on range measurements of the radar altimeter over ice and water between floes that yield freeboard, the height of the ice surface above the local sea level. With the density of ice and snow and snow depth itself, the freeboard can be converted into ice thickness. The Sea Ice Physics group investigates how the uncertainties in the assumptions and processing algorithms affect the sea ice thickness retrieval, for example the influence of snow properties on radar range estimations. The analysis is done in a full processing chain that takes calibrated raw data from ESA and produces freeboard and thickness maps currently of Arctic sea ice only. The results are available to the public via the data portal of meereisportal.de

The development work and the validation of the results with airborne surveys and ice station work is also part of international collaboration (e.g. the ESA Climate Change Initiative).

Sea-ice thickness estimates from CryoSat-2 are based on measuring the height of ice floes above the sea surface with radar altimeters
Sea-ice thickness estimates from CryoSat-2 are based on measuring the height of ice floes above the sea surface with radar altimeters (Graphic: AOES Medialab)