TY - JOUR

T1 - Assessment of CryoSat-2 interferometric and non-interferometric SAR altimetry over ice sheets

AU - McMillan, Malcolm

AU - Shepherd, Andrew

AU - Muir, Alan

AU - Gaudelli, Julia

AU - Hogg, Anna E.

AU - Cullen, Robert

PY - 2018/9/15

Y1 - 2018/9/15

N2 - The launch of CryoSat-2 heralded a new era of interferometric Synthetic Aperture Radar altimetry over the Polar Ice Sheets. The mission's novel SAR interferometric (SARIn) mode of operation has enabled monitoring of rapidly changing coastal regions, which had been challenging for previous low resolution altimeters. Given the growing requirement to continue the 25-year altimeter record, there is now a need to assess the differences between existing SAR and SARIn altimeter datasets, with a view to understanding the impact on ice sheet retrievals of the different radar hardware and processing methodologies. Uniquely, CryoSat-2 data can be processed both with and without interferometric information, offering the opportunity to directly compare the SAR and SARIn products generated by the current ground segment. Here, we provide a first comparison of these Level-2 datasets, and evaluate their capacity to measure ice sheet elevation and elevation change. We find that the current interferometric product has substantially improved precision, accuracy and coverage compared to its non-interferometric counterpart, yielding a ∼35% improvement in the root-mean-square-difference (RMSD) of elevations recorded at orbital cross-overs, and a ∼30% lower RMSD of elevation rates relative to Operation IceBridge airborne altimeter measurements. This analysis demonstrates the value that the interferometer adds to the current CryoSat-2 configuration, and highlights the importance for non-interferometric SAR Level-2 processing of the auxiliary data used to identify the location of the echoing point. These results provide a benchmark of the relative performance of the Level-2 interferometric and non-interferometric products currently produced by the ground segment, which will help to inform the design and implementation of a future polar radar altimeter mission.

AB - The launch of CryoSat-2 heralded a new era of interferometric Synthetic Aperture Radar altimetry over the Polar Ice Sheets. The mission's novel SAR interferometric (SARIn) mode of operation has enabled monitoring of rapidly changing coastal regions, which had been challenging for previous low resolution altimeters. Given the growing requirement to continue the 25-year altimeter record, there is now a need to assess the differences between existing SAR and SARIn altimeter datasets, with a view to understanding the impact on ice sheet retrievals of the different radar hardware and processing methodologies. Uniquely, CryoSat-2 data can be processed both with and without interferometric information, offering the opportunity to directly compare the SAR and SARIn products generated by the current ground segment. Here, we provide a first comparison of these Level-2 datasets, and evaluate their capacity to measure ice sheet elevation and elevation change. We find that the current interferometric product has substantially improved precision, accuracy and coverage compared to its non-interferometric counterpart, yielding a ∼35% improvement in the root-mean-square-difference (RMSD) of elevations recorded at orbital cross-overs, and a ∼30% lower RMSD of elevation rates relative to Operation IceBridge airborne altimeter measurements. This analysis demonstrates the value that the interferometer adds to the current CryoSat-2 configuration, and highlights the importance for non-interferometric SAR Level-2 processing of the auxiliary data used to identify the location of the echoing point. These results provide a benchmark of the relative performance of the Level-2 interferometric and non-interferometric products currently produced by the ground segment, which will help to inform the design and implementation of a future polar radar altimeter mission.

KW - Antarctica

KW - CryoSat-2

KW - Geodesy

KW - Ice sheets

KW - SAR altimetry

KW - Satellite radar interferometry

U2 - 10.1016/j.asr.2017.11.036

DO - 10.1016/j.asr.2017.11.036

M3 - Journal article

AN - SCOPUS:85039041244

VL - 62

SP - 1281

EP - 1291

JO - Advances in Space Research

JF - Advances in Space Research

SN - 0273-1177

IS - 6

ER -