OSCAT as a successor to QuikSCAT: a comparison over Arctic sea ice with emphasis on the seasonal melt-freeze transitions
(English)In: Annals of Glaciology, ISSN 0260-3055, E-ISSN 1727-5644Article in journal (Refereed) Submitted
It is important to continuously monitor the seasonal melt-freeze transitions because of their influence on the Arctic climate system. The Ku-band scatterometer QuikSCAT was widely used to retrieve the seasonal transitions before its antenna failed in November 2009. In this study, we show that OSCAT, a Ku-band scatterometer launched in September 2009, can serve as a successor to QuikSCAT over Arctic sea ice. This is done by (1) comparing backscatter measurements acquired in overlapping time periods, and by (2) retrieving the seasonal melt-freeze transitions over Arctic sea ice from resolution-enhanced QuikSCAT and OSCAT data and comparing the results, also with other datasets. The main difference between the instruments, in terms of backscatter measurements, is the incidence angle in which backscatter is acquired, which yields backscatter discrepancies of 1-2 dB. This discrepancy is significantly smaller than the response of both sensors to surface melting and freezing processes. An edge-detection algorithm is employed that retrieves seasonal transitions from QuikSCAT (1999-2009) and OSCAT (2011-2013) at a 4.45-km spatial resolution. A comparison with transitions retrieved from the C-band scatterometer ASCAT (2009-2013) and from passive microwave radiometers (1999-2013) indicates that the transitions from scatterometers are largely consistent across all regions in the Arctic sea-ice domain.
surface melt, remote sensing, sea-ice dynamics, sea-ice growth and decay, snow/ice surface processes
Meteorology and Atmospheric Sciences
Research subject Atmospheric Sciences and Oceanography
IdentifiersURN: urn:nbn:se:su:diva-99929OAI: oai:DiVA.org:su-99929DiVA: diva2:689541