Ocean melting of the Zachariae Isstrøm and Nioghalvfjerdsfjorden glaciers, northeast Greenland.
Ocean melting of the Zachariae Isstrøm and Nioghalvfjerdsfjorden glaciers, northeast Greenland.
复制标题
DOI：
10.1073/pnas.2015483118
复制
发表时间：
2021-01-12
影响因子：
11.1
通讯作者：
Khan SA
中科院分区：
文献类型：
--
作者：
An L;Rignot E;Wood M;Willis JK;Mouginot J;Khan SA
格陵兰岛东北部的海洋学和重力资料揭示了Zachariae Isstrøm （ZI）和Nioghalvfjerdsfjorden （79N）前的海洋温度和水深特征，这两个区域具有1.1 m的海平面上升冰量当量，但经历了不同的演变过程。由于水深障碍，来自大西洋的地下温暖咸水更容易进入ZI，而不是79N。我们从海冰变薄的角度重建了搁浅线的海冰消融和浮力后退，以解释自1979年以来观测到的搁浅线后退。观测退缩和计算退缩之间的一致表明，海洋热强迫是冰川演变的主要控制因素，为了再现高退缩率，数值冰盖模式必须包括地面冰的削弱。Zachariae Isstrøm （ZI）和Nioghalvfjerdsfjorden （79N）是格陵兰岛东北部的海洋冰川，其冰量相当于全球海平面上升1.1米。ZI失去了漂浮的冰架，加速，以650米/年的速度后退，并经历了50亿吨/年的质量损失。79N冰川尽管暴露在同样的气候强迫下，却更加稳定。我们分析了海洋热强迫对冰川的影响。航空重力数据的三维反演揭示了一条800米深的宽阔通道，该通道允许地下温暖的大西洋中间水（+1℃）通过350米深的两个基板到达ZI的前部。自1979年以来，该海峡的海底温度上升了1.3摄氏度。使用海洋模型，我们计算了1979-2019年间海洋在接地线上的冰移除率，从108米/年增加到185米/年。观测到的冰变薄导致其浮选线的后退从105米/年增加到217米/年，41年的综合接地线后退13公里，与独立观测结果在14%以内相匹配。相比之下，AIW通过较窄的通道进入79N的有限通道产生较低的接地冰移除（53米/年至99米/年）和变薄引起的后退（27米/年至50米/年），合计后退4.4公里，也在观测值的12%以内。因此，海洋在接地线引起的冰的移动，受到水深障碍的调节，是冰盖退缩的主要驱动力，但大多数冰盖模型没有考虑到这一点。
Oceanography and gravity data of northeastern Greenland reveal ocean temperature and bathymetry in front of Zachariae Isstrøm (ZI) and Nioghalvfjerdsfjorden (79N), which hold a 1.1-m sea level rise ice volume equivalent but underwent different evolutions. Subsurface, warm, salty water of Atlantic origin has easier access to ZI than to 79N because of bathymetric barriers. We reconstruct ice removal by the ocean at the grounding line and flotation retreat from thinning to explain the observed grounding line retreat since 1979. The agreement between observed and calculated retreat demonstrates that ocean thermal forcing is a major control on the glacier evolution, and undercutting of grounded ice must be included in numerical ice sheet models to reproduce the high rates of retreat. Zachariae Isstrøm (ZI) and Nioghalvfjerdsfjorden (79N) are marine-terminating glaciers in northeast Greenland that hold an ice volume equivalent to a 1.1-m global sea level rise. ZI lost its floating ice shelf, sped up, retreated at 650 m/y, and experienced a 5-gigaton/y mass loss. Glacier 79N has been more stable despite its exposure to the same climate forcing. We analyze the impact of ocean thermal forcing on the glaciers. A three-dimensional inversion of airborne gravity data reveals an 800-m-deep, broad channel that allows subsurface, warm, Atlantic Intermediate Water (AIW) (+1.C) to reach the front of ZI via two sills at 350-m depth. Subsurface ocean temperature in that channel has warmed by 1.3C since 1979. Using an ocean model, we calculate a rate of ice removal at the grounding line by the ocean that increased from 108 m/y to 185 m/y in 1979–2019. Observed ice thinning caused a retreat of its flotation line to increase from 105 m/y to 217 m/y, for a combined grounding line retreat of 13 km in 41 y that matches independent observations within 14%. In contrast, the limited access of AIW to 79N via a narrower passage yields lower grounded ice removal (53 m/y to 99 m/y) and thinning-induced retreat (27 m/y to 50 m/y) for a combined retreat of 4.4 km, also within 12% of observations. Ocean-induced removal of ice at the grounding line, modulated by bathymetric barriers, is therefore a main driver of ice sheet retreat, but it is not incorporated in most ice sheet models.
登录
查看更多内容
影响因子：
56.9
作者：
Mouginot, J.;Rignot, E.;Paden, J.
通讯作者：
Paden, J.
DOI：
10.1073/pnas.1904242116
发表时间：
2019-05-07
影响因子：
11.1
作者：
Mouginot, Jeremie;Rignot, Eric;Wood, Michael
通讯作者：
Wood, Michael
影响因子：
5.2
作者：
Rignot, E.;Xu, Y.;de Fleurian, B.
通讯作者：
de Fleurian, B.
DOI：
10.1111/j.1365-246x.1973.tb06513.x
发表时间：
1973-01-01
期刊：
GEOPHYSICAL JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY
影响因子：
--
作者：
PARKER, RL
通讯作者：
PARKER, RL
影响因子：
30.7
作者：
Khan, Shfaqat A.;Kjaer, Kurt H.;Muresan, Ioana S.
通讯作者：
Muresan, Ioana S.