Abstract
Abstract. This paper presents the first long-term climate data record of sea ice extents and backscatter derived from intercalibrated satellite scatterometer missions (ERS, QuikSCAT and ASCAT) extending from 1992 to the present date (Verhoef et al., 2018). This record provides a valuable independent account of the evolution of Arctic and Antarctic sea ice extents, one that is in excellent agreement with the passive microwave records during the fall and winter months but shows higher sensitivity to lower concentration and melting sea ice during the spring and summer months. The scatterometer record also provides a depiction of sea ice backscatter at C- and Ku-bands, allowing the separation of seasonal and perennial sea ice in the Arctic and further differentiation between second-year (SY) and older multiyear (MY) ice classes, revealing the emergence of SY ice as the dominant perennial ice type after the historical sea ice loss in 2007 and bearing new evidence on the loss of multiyear ice in the Arctic over the last 25 years. The relative good agreement between the backscatter-based sea ice (FY, SY and older MY) classes and the ice thickness record from Cryosat suggests its applicability as a reliable proxy in the historical reconstruction of sea ice thickness in the Arctic.
Highlights
Dating as far back as 1978, passive microwave sensors provide the longest record of sea ice concentration and extents available to date and are currently established as the sea ice monitoring standard for climate studies, regardless of well-known difficulties around the detection of lower concentration and melting sea ice conditions during the summer months (Meier et al, 2015)
We present the first intercalibrated long-term record of sea ice extents and backscatter derived from satellite scatterometer missions (ERS, QuikSCAT and Advanced Scatterometer (ASCAT)) extending from 1992 to the present date
The scatterometer record, the continuation of which is guaranteed by the Metop ASCAT (B and C) and EPS-SG series into the future, provides a valuable independent account of the state of Arctic and Antarctic www.the-cryosphere.net/12/2941/2018/
Summary
Dating as far back as 1978, passive microwave sensors provide the longest record of sea ice concentration and extents available to date and are currently established as the sea ice monitoring standard for climate studies, regardless of well-known difficulties around the detection of lower concentration and melting sea ice conditions during the summer months (Meier et al, 2015). An independent record of sea ice extents has been produced from intercalibrated scatterometer data: the QuikSCAT mission from 1999 to 2009 (Belmonte Rivas and Stoffelen, 2011), extended forward to the present day with the ASCAT record (Belmonte Rivas et al, 2012) and backwards to 1992 with the ERS mission (Otosaka et al, 2017) using dedicated Bayesian sea ice detection algorithms designed to maximize the skill for ocean–ice discrimination. We provide an overview of the long-term evolution of sea ice extents and sea ice types afforded by 25 years of scatterometer data, along with a taste of its potential to stimulate new research questions
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