利用 ICESat 数据确定北冰洋海冰出水高度--以2005-2006年为例

摘要

Based on variation characters of sea surface height and parameters of ICESat return pulse waveform,a method is proposed for estimating Arctic sea ice freeboard with ICESat observation.This proposed method is compared with the common ‘lowest-level’method.The results show that the lowest-level method is vulnerable to gross errors and present systematic errors in spatial distribution of freeboard. But the proposed method is more rel iable than the lowest-level method.The lowest-level method is improved by the employ of an elevation standard deviation threshold and combined with the proposed method to estimate sea ice freeboard for six ICESat campaigns between 2005 and 2006 to review the seasonal variabi l ity.The results show that the abnormal cl imate in the summer of 2005 have a profound impact on arctic sea ice,which caused the decrease of freeboard and changed the constituent of sea ice as wel l.%提出了在结合高程特征变化的基础上利用 ICESa t 海冰观测数据波形参数确定北冰洋海冰出水高度的方法,并与目前常用的最低点法进行比较。结果表明,最低点法计算的海冰出水高度不仅在空间分布上存在系统性误差,并且容易受到粗差影响,而本文的方法则具有较高的可靠性。本文在最低点法中加入高程标准差限制,并与本文提出的方法结合,计算并分析了2005年至2006年6个 ICESa t 任务期的北冰洋海冰出水高度的季节变化。结果表明,2005年夏天的异常气候对于北冰洋海冰具有深远的影响,不仅使当年秋季的海冰出水高度大大减小,而且海冰的组成比例也发生了巨大变化。