Antarctic Sea Ice Thickness from Airborne LiDAR and Ultra-wideband Radar, 20-R8181
Principal Investigators
Michael Lewis
Marius Necsoiu
Jorge Parra
Inclusive Dates: 10/01/10 – 04/01/12
Background — The cryosphere is intricately linked to the global climate system and the Earth's surface energy budget. Sea ice is a primary component of the polar oceans and comprises approximately 7 percent of the Earth’s surface in the mean. Sea ice is important to the global climate system because of its prominent role in the 'ice-albedo' feedback mechanism that enhances climate response at high latitudes; influence on the exchange of heat, gases, and momentum between the ocean and atmosphere; and effects on buoyancy of ocean currents caused by changing fresh and saline water inputs. Despite increased research focus in recent years, the Antarctic sea-ice zone remains one of the least-known regions of the Earth’s surface. The remote location, limited extent and infrequency of direct measurements, and difficulties in validation of remote sensing products have contributed to the knowledge gap.
This project involves direct collaboration with the British Antarctic Survey (BAS), Scottish Association of Marine Science (SAMS) and other international participants to obtain in situ sea ice measurements during the ICEBell program in November 2010. The data from this program were used to derive sea ice and snow cover thickness relationships in the Antarctic sea ice zone and ultimately will be used to improve satellite remote sensing products, allowing long term monitoring of the ice mass balance in the Antarctic sea ice zone.
Approach — The project comprises two basic tasks. The first task involves participation in ICEBell cruise aboard the James Clark Ross to obtain detailed snow and ice measurements that are coincident with airborne and satellite remote sensing measurements. The second task involves analyses of field campaign and airborne LiDAR and satellite remote sensing data necessary to assess statistical relationships between surface elevation, snow depth, freeboard, ice thickness, and roughness with the ultimate goal of classifying sea ice types and calculating sea-ice thickness from satellite altimetry and active radar returns.
Sea-ice measurements were obtained from the BAS icebreaker James Clark Ross in areas of the northwestern Weddell Sea and in the Bellingshausen Sea, Antarctica. The field program was performed in conjunction with near-coincident airborne LiDAR surveys and satellite (remote sensing) radar measurements. It was originally planned to coincide with NASA IceBridge flights acquiring both LiDAR and Snow (Ku band) radar along flight lines in the Bellingshausen Sea; however, unanticipated delays in the JCR schedule precluded the overlap of IceBridge flights.
Accomplishments —
Successfully participated in the BAS ICEBell sea-ice cruise, collecting gridded surveys with geophysical measurements on 10 separate sites on 8 different sea-ice floes in the Weddell and Bellingshausen Seas and placing 12 ice mass-balance buoys (IMBs) that drifted with the floes for months following the cruise.
Coordinated the acquisition of 40 TerraSAR-X (X-band radar) images through the German Aerospace Agency, EnviSat radar and AMSR-E passive microwave satellite data that were coincident in time and location with IMBs during the drift period.
Developed a methodology to analyze decomposition products from TerraSAR-X datasets in the Bellingshausen Sea to derive polarimetric parameters for sea-ice floes that may subsequently be correlated with sea-ice type.
Co-registered overlapping terrestrial scanning LiDAR datasets for all floe sites.
Developed geostatistical relationships and probability distributions for sea-ice floes using surface elevation, snow depth, freeboard, and ice thickness for correlation with polarimetric parameters.
Built successful relationships with a significant group of external collaborators who contributed to various aspects of the project.
Identified new avenues of research related to Antarctic sea ice that allow a multi-sensor approach to monitor sea-ice thickness from remotely sensed data sets with application to long-term climate change impact assessments.
