西南极冰盖 2002–2023 年冰川尺度的点质量模型解算与分析

Solution and Analysis of Glacier-Scale Point-Mass Modeling for the West Antarctic Ice Sheet from 2002 to 2023

  • 摘要: 利用重力场恢复与气候实验卫星(gravity recovery and climate experiment, GRACE) 及其后继卫星 GRACE-FO(GRACE Follow-On) 解算的 Tongji-Grace2022 时变重力场模型, 并用卫星测高数据构建高分辨率约束信息, 采用两步点质量建模方法解算了西南极冰盖 2002-04—2023-12 冰川尺度的高分辨率( 27 km×27 km) 点质量产品。在研究时段内, 产品估计的西南极冰盖质量变化趋势为-139.36±19.92 Gt/a, 对全球平均质量海平面变化的贡献量为 0.38 ± 0.06 mm/a, 与三大 GRACE 官方机构全球点质量产品的估计结果一致, 但空间分辨率显著提高。利用独立的输入输出法产品评估了三个GRACE 官方机构产品、 卫星测高产品及本文产品。结果表明, 本文产品对西南极 20 个冰川(组) 质量变化趋势估计表现最优, 其线性回归系数和R2值分别为 0.82 和 0.93, 显著高于其他点质量产品, 且截距最小; 与卫星测高产品相比, 本文产品的R2值更高且截距更小, 展示出更高的估计精度。研究时段内, 西南极冰盖的长期表面物质异常与冰动力相关质量变化率分别为-11.70 ± 0.59 Gt/a 和-113.58 ±6.56 Gt/a, 表明冰动力相关质量变化是西南极冰盖质量损失的主要驱动因素; Pine Island、 Thwaites、Getz 冰川及 PSKP 冰川组(Pope、 Smith、 Kohler、 Philbin 冰川) 4 个冰川(组) 的长期质量变化率之和约占西南极冰盖的 90%, 其变化率依次分别为-44.19±3.33、 -26.17±5.44、 -27.04±0.94 和-27.92±1.02Gt/a, 对全球海平面变化的贡献率依次为 0.12±0.01、 0.072±0.015、 0.075±0.003 和 0.077±0.003 mm/a。

     

    Abstract: Using a two-step point-mass modeling method, a high-resolution (27 km × 27 km) point-mass product over the WAIS (West Antarctic Ice Sheet) at a glacier scale from April 2002 to December 2023 is derived. This method employs the Tongji-Grace2022 time-variable gravity field model derived from the GRACE (Gravity Recovery and Climate Experiment) and its successor GRACE-FO (GRACE Follow-On), and high-resolution constraint information from satellite altimetry are employed. Over the study period, the estimated mass change rate of the WAIS is -139.36 ± 19.92 Gt/a, contributing a global mean sea level rise of 0.38 ± 0.06 mm/a, which is consistent with the estimates from the global mascon (mass concentration) products of the three major GRACE official institutions but with significantly improved spatial resolution. Through regression fitting, we evaluated the products from the three major official institutions, satellite altimetry products, and our product using an independent product derived from input-output method. The results demonstrate that our product outperforms the others in estimating mass change rates for 20 glaciers (groups) in the WAIS. It has the smallest intercept, with coefficients of 0.82 for linear regression and an R2 of 0.93, both significantly higher than those of the counterparts. Compared to satellite altimetry results, our product has a higher R2 and a smaller intercept, indicating higher estimation accuracy. During the study period, the longterm surface mass anomaly and ice dynamics-related mass change rates of the WAIS are -11.70 ± 0.59 Gt/a and -113.58 ± 6.56 Gt/a, respectively, indicating that ice dynamics is the dominant factor of the overall mass loss. The combined long-term mass change rates of four major glaciers (or glacier groups)—Pine Island, Thwaites, Getz, and the PSKP (Pope, Smith, Kohler, and Philbin glaciers) glacier group—account for approximately 90% of the total mass change in the WAIS. Their individual rates are -44.19 ± 3.33, -26.17 ± 5.44, -27.04 ± 0.94, and -27.92 ± 1.02 Gt/a, respectively, with corresponding contributions to global mean sea level rise of 0.12 ± 0.01, 0.072 ± 0.015, 0.075 ± 0.003, and 0.077 ± 0.003 mm/a respectively.

     

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