卫星重力估计陆地水和冰川对全球海平面变化的贡献

Land water and glaciers contributions to global sea level change from satellite gravity measurements

重力场恢复与气候试验(GRACE)卫星为高分辨率地监测全球海洋质量变化提供了一种新的手段。利用2003年1月至2014年12月Level-2 RL05的GRACE产品,进行去相关误差滤波、高斯滤波和海洋-陆地信号泄漏改正后,得到了全球陆地和海水质量变化,并分析了陆地水和冰川的质量变化对海平面长期变化的贡献。研究表明,全球陆地水和冰川的质量变化对海平面的贡献约为(2.09±0.54)mm/a,与卫星测高扣除海洋温盐数据比热容变化得到的海水质量长期变化(2.07±0.62)mm/a有着很好的一致性,其中全球陆地水储量对全球质量项海平面变化的贡献为(0.15±0.25)mm/a,南极冰盖对全球质量项海平面变化的贡献为(0.59±0.10)mm/a,格陵兰岛冰盖对全球质量项海平面变化的贡献为(0.72±0.12)mm/a,山地冰川对全球质量项海平面变化的贡献为(0.63±0.09)mm/a。并进一步讨论了不同分析中心GRACE重力场系数,一阶项系数和二阶项对质量项海平面变化的影响。结果表明,一阶项对质量项海平面的影响为(0.10±0.08)mm/a,二阶项对质量项海平面的影响为(0.16±0.04)mm/a,美国德克萨斯大学空间研究中心和德国地学研究中心分析结果较为一致,而美国国家航空航天局喷气推进实验室的结果则稍稍偏小。

The Gravity Recovery and Climate Experiment(GRACE)satellite mission launched in 2002 provided an opportunity to estimate the global land and ocean water mass variations with high temporal-spatial resolution.In this paper,we use the GRACE RL05 data from January 2003 to December 2014 to estimate the ocean mass variations.We applied 500 km Gaussian smoothing,a decorrelation filtering and a forward modelling to reduce the land-ocean leakage effects.Land water and glaciers contributions to global sea level change are investigated.Results show that the long-term trend of the mass-induced sea level variations is(2.09±0.54)mm/a,which has a good agreement with the steric sea level change of(2.07±0.62)mm/a from the satellite altimetry and Argo data.The contribution of land water to sea level change is(0.15±0.25)mm/a.The glacier melting contribution to sea level rise is(0.72±0.12)mm/a in Greenland,(0.59±0.10)mm/a in Antarctica,and(0.63±0.09)mm/a for the mountain glaciers(including Alaska,Iceland,Canadian Arctic,High Mountain Asia and Patagonia).Furthermore,the impact of the GRACE gravity field coefficients from different GRACE analysis centers(CSR,JPL and GFZ),first-order coefficient and the second-order coefficient to sea level change are discussed.The impact of first-order coefficient to the mass-induced sea level variations is(0.10±0.08)mm/a,and the second-order coefficient to the mass-induced sea level variations is(0.16±0.04)mm/a.The results from CSR are consistent with GFZ results,while the JPL’s results are slightly smaller.