A Decade of QuikSCAT Scatterometer Sea Ice Extent Data

• Main Authors: Quinn P. Remund, David G. Long
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Arctic; The Antarctic; Antarc*; Antarctica; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.637.7042; http://www.mers.byu.edu/long/papers/TGARS2014_Remund.pdf

Abstract—Polar sea ice is an important input to global cli-mate models and is considered to be a sensitive indicator of cli-mate change. While originally designed only for wind estimation, radar backscatter measurements collected by wind scatterometers have proven useful for estimating the extent of sea ice. During the Quick Scatterometer (QuikSCAT) mission, SeaWinds data were used to operationally map the sea ice extent. The resulting sea ice maps were used to mask near-surface winds to support SeaWinds ’ primary mission of measuring near-surface winds over the ocean. This paper describes the operational SeaWinds sea ice extent mapping algorithm, provides validation comparisons, and presents results from the ten-year data product. Starting with enhanced resolution horizontal polarization and vertical polar-ization backscatter images, the algorithm employs an iterative maximum-likelihood classifier with fixed thresholds to segment sea ice and open ocean pixels. Residual classification errors are reduced through binary image processing techniques and sea ice growth/retreat constraint methods. The algorithm results are compared with sea ice concentrations derived from Special Sensor Microwave/Imager data and with RADARSAT synthetic aperture radar imagery. The results suggest differences in the sensitivities of active and passive products given their channel sets and spe-cific algorithms. Derived sea ice extents over the full decade-long QuikSCAT mission data set are analyzed to show important trends in sea ice extent for the Antarctic and Arctic regions. Index Terms—Antarctica, Arctic, maximum likelihood (ML) detection, microwave sensors, microwave radiometry, QuikSCAT, radar remote sensing, sea ice, SeaWinds. I.