Empirical parametrization of Envisat freeboard retrieval of Arctic and Antarctic sea ice based on CryoSat-2: progress in the ESA Climate Change Initiative


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Robert.Ricker [ at ] awi.de

Abstract

In order to derive long-term changes in sea-ice volume, a multi-decadal sea-ice thickness record is required. CryoSat-2 has showcased the potential of radar altimetry for sea-ice mass-balance estimation over the recent years. However, precursor altimetry missions such as Environmental Satellite (Envisat) have not been exploited to the same extent so far. Combining both missions to acquire a decadal sea-ice volume data set requires a method to overcome the discrepancies due to different footprint sizes from either pulse-limited or beam-sharpened radar echoes. In this study, we implemented an inter-mission-consistent surface-type classification scheme for both hemispheres, based on the waveform pulse peakiness, leading-edge width, and surface backscatter. In order to achieve a consistent retracking procedure, we adapted the threshold first-maximum retracker algorithm, previously used only for CryoSat-2, to develop an adaptive retracker threshold that depends on waveform characteristics. With our method, we produce a global and consistent freeboard data set for CryoSat-2 and Envisat. This novel data set features a maximum monthly difference in the mission-overlap period of 2.2cm (2.7cm) for the Arctic (Antarctic) based on all gridded values with spatial resolution of 25 km  ×  25 km and 50 km  ×  50 km for the Arctic and Antarctic, respectively.



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ISI/Scopus peer-reviewed
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Published
Eprint ID
48619
DOI 10.5194/tc-12-2437-2018

Cite as
Paul, S. , Hendricks, S. , Ricker, R. , Kern, S. and Rinne, E. (2018): Empirical parametrization of Envisat freeboard retrieval of Arctic and Antarctic sea ice based on CryoSat-2: progress in the ESA Climate Change Initiative , The Cryosphere, 12 (7), pp. 2437-2460 . doi: 10.5194/tc-12-2437-2018


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