基于CryoSat-2数据的海冰厚度估算算法比较

Comparison of Sea Ice Thickness Retrieval Algorithms from CryoSat-2 Satellite Altimeter Data

  • 摘要: 以北极为研究区,使用CryoSat-2数据,利用现有海冰厚度卫星测高研究中4种主流算法(Laxon03算法、Kurtz09算法、Yi11算法和Laxon13算法)分别对北冰洋海冰厚度进行估算,并将估算结果与研究区IceBridge机载激光测高冰厚数据进行了比较,探索各算法海冰厚度估算的差异,寻找最优的估算算法,为估算长时序海冰厚度提供基础和参考。结果表明,4种算法估算的海冰厚度空间分布较为一致,但不同算法估算的结果差异较大,可达0.476 m;4种算法估算结果大小依次为Laxon03算法、Yi11算法、Laxon13算法、Kurtz09算法;4种算法估算的平均海冰厚度差异,在北极波弗特海海域最大,其次是北极中心海域、格陵兰和挪威海;Laxon13算法估算结果相对于IceBridge观测结果与其他算法相比,具有最小的平均偏差和均方根误差,是卫星测高估算海冰厚度的最优算法。

     

    Abstract: Sea ice thickness is an important parameter and indicator of climate change, sensitive to ecosystem in Polar Regions. For accurate forecasting of climate change, sea ice mass balance, ocean circulation and sea-atmosphere interactions, it is required to have long term records of sea ice thickness. Satellite altimetry provide useful technology for obtaining time series sea ice thickness information on hemispheric scale. So far, four mainstream algorithms based on satellite altimeter data have been used to estimate sea ice thickness effectively. Different algorithms and parameter values as selected by different researchers will lead to results unsuitable for comparison and large uncertainties. To solve this problem, this study compared sea ice thickness over the Arctic research area retrieved from these four mainstream algorithms based on CryoSat-2 satellite altimeter data. Our results demonstrate that: (1) when compared to each other, the retrieved mean sea ice thickness estimated from these four algorithms have similar spatial distribution, but with larger difference in the value, up to 0.476 m;(2) the sequence of estimated sea ice thickness for the Arctic spatial average based on four algorithms is Laxon03 algorithm, Yi11 algorithm, Laxon13 algorithm and Kurtz09 algorithm;(3) the difference of the mean sea ice thickness from these four algorithms was higher in Beaufort Sea than in Central Arctic or Greenland Sea;(4) The Laxon13 algorithm was the optimal algorithm, with the minimum bias and RMSE when compared to IceBridge sea ice thickness measurements. These results can provide useful reference and basis for further study to improve algorithms, so as to quantify dynamic changes of sea ice thickness more accurately.

     

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