Department of the Geophysical Sciences, The University of Chicago, Chicago, Illinois 60637, USA.
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2018 Apr 6;120(14):148701. doi: 10.1103/PhysRevLett.120.148701.
Climate change, amplified in the far north, has led to rapid sea ice decline in recent years. In the summer, melt ponds form on the surface of Arctic sea ice, significantly lowering the ice reflectivity (albedo) and thereby accelerating ice melt. Pond geometry controls the details of this crucial feedback; however, a reliable model of pond geometry does not currently exist. Here we show that a simple model of voids surrounding randomly sized and placed overlapping circles reproduces the essential features of pond patterns. The only two model parameters, characteristic circle radius and coverage fraction, are chosen by comparing, between the model and the aerial photographs of the ponds, two correlation functions which determine the typical pond size and their connectedness. Using these parameters, the void model robustly reproduces the ponds' area-perimeter and area-abundance relationships over more than 6 orders of magnitude. By analyzing the correlation functions of ponds on several dates, we also find that the pond scale and the connectedness are surprisingly constant across different years and ice types. Moreover, we find that ponds resemble percolation clusters near the percolation threshold. These results demonstrate that the geometry and abundance of Arctic melt ponds can be simply described, which can be exploited in future models of Arctic melt ponds that would improve predictions of the response of sea ice to Arctic warming.
气候变化在遥远的北方加剧，导致近年来北极海冰迅速减少。在夏季，北极海冰表面会形成融池，这大大降低了冰的反射率（反照率），从而加速了冰的融化。池塘的几何形状控制着这一关键反馈的细节；然而，目前还没有可靠的池塘几何形状模型。在这里，我们展示了一个简单的模型，该模型可以模拟随机大小和放置的重叠圆周围的空隙，从而再现池塘模式的基本特征。模型和池塘的航空照片之间的两个相关函数确定了典型池塘的大小及其连通性，模型中的两个参数，特征圆半径和覆盖率，是通过比较这两个函数来选择的。使用这些参数，空洞模型可以在 6 个数量级以上稳健地再现池塘的面积-周长和面积-丰度关系。通过分析几个日期的池塘相关函数，我们还发现池塘的规模和连通性在不同年份和冰型之间惊人地保持不变。此外，我们发现池塘类似于渗流阈值附近的渗流簇。这些结果表明，北极融池的几何形状和丰度可以简单地描述，这可以在未来的北极融池模型中得到利用，从而提高对北极变暖中海冰响应的预测。
