Arctic sea surface height variability and change from satellite radar altimetry and GRACE, 2003-2014
Arctic sea surface height variability and change from satellite radar altimetry and GRACE, 2003-2014
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DOI：
10.1002/2015jc011579
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发表时间：
2016-06-01
影响因子：
3.6
通讯作者：
Wingham, Duncan J.
中科院分区：
文献类型：
--
作者：
Armitage, Thomas W. K.;Bacon, Sheldon;Wingham, Duncan J.
由于常规高度计对极地海洋的覆盖范围较差，以及由于大片区域永远被海冰覆盖，需要专门的数据处理，雷达高度计对北极海面高度的观测效果很差。我们利用来自有冰海洋和无冰海洋的SSH估计，提出了北纬81.5度以南雷达测高对北极动力海洋地形(DOT)的每月估计，并将其与GRACE海洋质量结合起来估计空间高度。我们的SSH和空间高度估计与潮汐测量仪记录和冰系留剖面仪得出的位势高度有很好的一致性。北冰洋SSH的大周期(幅度接近5 cm)主要受与季节淡水通量相关的空间高度的季节变化所主导，并在10~11月达到高峰。总体而言，由于西伯利亚陆架海的大幅减少，2003年至2012年间，年平均立体高度增加了2.2+/-1.4厘米，而在2012年至2014年间，由于西伯利亚陆架海的大幅减少，空间高度下降到2003年左右的水平。2003年至2014年间SSH的长期变化主要是海洋质量增加了2.1+/-0.7厘米。我们估计，到2010年，与2003-2006年的平均值相比，波弗特盖尔已经积累了4600公里(3)的淡水。通过经验正交函数分析发现，波弗特海北极DOT的隆起与西伯利亚北极的区域减少是同步的。我们估计，2003年至2014年期间，西伯利亚陆架海失去了大约180公里(3)的淡水，与年平均盐度增加0.15PSU yr(-1)有关。最后，用测高方法估算的海洋存储通量与高分辨率模型结果吻合得很好，证明了用测高方法来阐明北极水文循环的潜力。
Arctic sea surface height (SSH) is poorly observed by radar altimeters due to the poor coverage of the polar oceans provided by conventional altimeter missions and because large areas are perpetually covered by sea ice, requiring specialized data processing. We utilize SSH estimates from both the ice-covered and ice-free ocean to present monthly estimates of Arctic Dynamic Ocean Topography (DOT) from radar altimetry south of 81.5 degrees N and combine this with GRACE ocean mass to estimate steric height. Our SSH and steric height estimates show good agreement with tide gauge records and geopotential height derived from Ice-Tethered Profilers. The large seasonal cycle of Arctic SSH (amplitude similar to 5 cm) is dominated by seasonal steric height variation associated with seasonal freshwater fluxes, and peaks in October-November. Overall, the annual mean steric height increased by 2.2 +/- 1.4 cm between 2003 and 2012 before falling to circa 2003 levels between 2012 and 2014 due to large reductions on the Siberian shelf seas. The total secular change in SSH between 2003 and 2014 is then dominated by a 2.1 +/- 0.7 cm increase in ocean mass. We estimate that by 2010, the Beaufort Gyre had accumulated 4600 km(3) of freshwater relative to the 2003-2006 mean. Doming of Arctic DOT in the Beaufort Sea is revealed by Empirical Orthogonal Function analysis to be concurrent with regional reductions in the Siberian Arctic. We estimate that the Siberian shelf seas lost similar to 180 km(3) of freshwater between 2003 and 2014, associated with an increase in annual mean salinity of 0.15 psu yr(-1). Finally, ocean storage flux estimates from altimetry agree well with high-resolution model results, demonstrating the potential for altimetry to elucidate the Arctic hydrological cycle.