Estimation of wintertime Arctic sea ice thickness with satellite scatterometers

• Main Author: Egbers, Ruben (author)
• Other Authors: Belmonte Rivas, Maria (mentor), Lhermitte, S.L.M. (graduation committee), Slobbe, D.C. (graduation committee), Hanssen, R.F. (graduation committee), Delft University of Technology (degree granting institution)
• Format: Master Thesis
• Language: English
• Published: 2019
• Subjects: Arctic; sea ice thickness; scatterometers; ERS; ASCAT; QuikSCAT; estimation; ICESat; CryoSat-2; Sea ice
• Online Access: http://resolver.tudelft.nl/uuid:fc61066f-7acc-49a8-8ceb-6223ce90c063

Accurate information on Arctic sea ice thickness has been historically limited both spatially and temporally to spare submarine sonar measurements until the advent of satellite altimeters such as ICEsat (operating from 2002 to 2008) and CryoSat-2 (operating from 2011 to present day). This study aims to use the historical record of normalized radar backscatter measurements from satellite Ku-band and C-band scatterometers (ERS, QuikSCAT and ASCAT), which have been continuously operating since 1992, to homogenize the satellite altimeter record and extend the record of Arctic sea ice thickness measurements backwards in time. This study is structured so as to first derive a set of empirical relationships between normalized backscatter measurements and wintertime sea ice thickness estimates in the Arctic using existing satellite altimeter records as a reference. Two separate scatterometer sea ice thickness models are produced using coincident scatterometer and altimeter observations, one for C-band sea ice thickness estimation using ASCAT and CryoSat-2 collocations, and another for Ku-band sea ice thickness estimation using QuikSCAT and ICESat collocations. Based on the agreement to the altimeter records, the estimation of wintertime sea ice thickness using the C-band and Ku-band scatterometer models is uncertain to within 0.5 m (1-sigma), that is, a precision similar to that of the original altimeter references. The homogenization of the satellite altimeter records cannot be done directly, because the ICESat and CryoSat-2 instruments operate in different periods, but it can be done indirectly by comparing the sea ice thickness estimates obtained from Ku-band (based on ICESat) and C-band (based on CryoSat-2) estimates during the years that the Ku-band and C-band scatterometers operate simultaneously. These overlap years have been used to verify the consistency between the C-band and Ku-band relationships, and to correct for a 0.55 m bias in the CryoSat-2 reference, having considered the earlier ICESat record as ...