Large‐scale comparison between buoy and SSM/I drift and deformation in the Eurasian Basin during winter 1992–1993

Authors:
  • CGCathleen A. Geiger
    Cathleen A. Geiger
  • YZYunhe Zhao
    Yunhe Zhao
  • ALAntony K. Liu
    Antony K. Liu
  • SHSirpa Häkkinen
    Sirpa Häkkinen
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Abstract
A method for comparing sea ice velocity, divergence, and shear at the large‐scale between buoys and Special Sensor Microwave Imager (SSM/I) is presented. For initial testing, the method is applied in the Eurasian Basin because of its relatively simple circulation dominated by the wind. Using eight Argos buoys, 11 strain rate arrays 100–600 km in size are constructed. Daily 100 km resolution sea ice motion derived from SSM/I 85 GHz brightness temperatures is sampled 100–1000 km from the center of the buoy arrays. Over this range of possible scales, a minimum RMS difference (RMSD) for deformation is used to identify an optimal inclusion radius of 600 km corresponding to a length scale of 1000 km. This length scale is typical of local storms confirming a strong connection between wind and observed sea ice motion. On the basis of all 11 arrays, an average RMSD of 2.48±0.05 cm s−1 for velocity vector and 8.8±0.9×10−8 s−1 using all four deformation components (∂ui/∂χj∥ is found at the optimal inclusion radius corresponding to average correlation coefficients of 0.896±0.002 and 0.729±0.030, respectively. RMSD are found to scale with the temporal and spatial uncertainties of the SSM/I suggesting that even better results can be achieved with higher resolution instruments.

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