Cloud-driven modulations of Greenland ice sheet surface melt
Cloud-driven modulations of Greenland ice sheet surface melt
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DOI：
10.1038/s41598-019-46152-5
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发表时间：
2019-07-17
影响因子：
4.6
通讯作者：
Aoki, Teruo
中科院分区：
文献类型：
--
作者：
Niwano, Masashi;Hashimoto, Akihiro;Aoki, Teruo
人们已经认识到云会加速格陵兰冰盖（GrIS）的表面融化。然而，云对GrIS融化面积和整个冰盖表面质量平衡影响的定量估计仍然缺乏。在这里，我们用最先进的区域气候模式评估云的影响，进行了一个数值敏感性测试，其中假设绝热大气条件和零云水/冰量（即晴空条件），尽管降水率与控制的全天模拟相同。通过包括或排除云，我们首次量化了时间集成反馈。我们发现，在2012年、2013年和2014年，云层分别对（GrIS总面积）地表融化程度增加3.1%、0.3%和0.7%负责。在同一时期，云分别减少了1.6、0.8和1.0 Gt day（-1）的太阳加热，从而减少了日径流量；云没有增加地表质量损失。在消融区，云的存在导致了雪/冰表面向下潜热通量的减少，使得用于表面融化的能量大大减少，这突出了云辐射效应的间接时间积分反馈的重要性。
Clouds have been recognized to enhance surface melt on the Greenland Ice Sheet (GrIS). However, quantitative estimates of the effects of clouds on the GrIS melt area and ice-sheet-wide surface mass balance are still lacking. Here we assess the effects of clouds with a state-of-the-art regional climate model, conducting a numerical sensitivity test in which adiabatic atmospheric conditions as well as zero cloud water/ice amounts are assumed (i.e., clear-sky conditions), although the precipitation rate is the same as in the control all-sky simulation. By including or excluding clouds, we quantify time-integrated feedbacks for the first time. We find that clouds were responsible for a 3.1%, 0.3%, and 0.7% increase in surface melt extent (of the total GrIS area) in 2012, 2013, and 2014, respectively. During the same periods, clouds reduced solar heating and thus daily runoff by 1.6, 0.8, and 1.0 Gt day(-1), respectively: clouds did not enhance surface mass loss. In the ablation areas, the presence of clouds results in a reduction of downward latent heat flux at the snow/ice surface so that much less energy is available for surface melt, which highlights the importance of indirect time-integrated feedbacks of cloud radiative effects.