Role of radiative forcing on the sea ice melt-growth cycle in a changing Arctic marine environment

由于全球变暖，北极海冰覆盖率迅速下降，2012年9月又创新低。冰盖的减少对极地海洋环境产生了明显的影响。然而，这对未来气候变化、碳循环和生态系统的影响程度仍不确定。从根本上讲，表面辐射强迫如何影响海冰特性的变化，以及这些变化如何反过来调节强迫。这种相互作用构成了北极复杂气候反馈的基础。考虑到每年形成然后融化的海冰面积广阔（约1000万平方公里或大致相当于加拿大的大小），全面了解推动这一周期的过程的重要性怎么强调都不过分。 鉴于此，在拟议的研究中要解决的目标是调查1）辐射强迫和海冰表面融化演变之间的相互反馈，2）与多孔海冰结构和嵌入杂质的小尺度相互作用如何影响海冰内部的辐射传输，以及3）冰下辐射场和光学特性的变化对水柱加热和海冰融化速率的重要性。 这三个目标将有助于回答有关海冰融化如何在表面，内部和底部之间分配的问题，以及有多少热量保留在海洋上层，在那里它可以导致秋季冻结的延迟。我们预测未来气候的能力取决于对这些过程的理解。这些目标是相互关联的，但单独为硕士和博士研究提供合适和独特的项目。这项研究将促进我们对海冰过程和气候反馈的了解，培养北极环境研究的新学生，并最终通过改善气候预测，帮助社区和各级政府适应气候变化，使北方人受益。

The Arctic sea ice cover is in rapid decline due to global warming with yet another new record low reached in September 2012. The diminishing ice cover is having a discernible impact on the polar marine environment. However, the extent of this impact on future changes to climate, carbon cycling and ecosystems remains uncertain. At the root is how surface radiative forcing affects changes in sea ice properties, and how these changes in turn modulate the forcing. Such interactions form the base of complex climate feedbacks operating in the Arctic. Considering the vastness of the area of sea ice (~10 million km2 or roughly the size of Canada) that forms and then melts each year, the importance of a comprehensive understanding of the processes driving this cycle cannot be overstated.** Given this, the objectives to be addressed in the proposed research are to investigate 1) the reciprocal feedbacks between radiative forcing and the melt evolution of the sea ice surface, 2) how small-scale interactions with the porous sea ice structure and imbedded impurities affect radiative transfer within the sea ice interior, and 3) the importance of variable under-ice radiation fields and optical properties on water column heating and sea ice melt rates.** These three objectives will help answer questions about how sea ice melt is partitioned between surface, interior and bottom, and how much heat is retained in the upper ocean layers where it can cause a delay in the fall freeze-up. Our ability to predict future climate rests on understanding these processes. The objectives are interrelated, yet individually provide suitable and distinct projects for both MSc and PhD studies. This research will advance our knowledge of sea ice processes and climate feedbacks, train new students in Arctic environmental research and ultimately, benefit northerners by improving climate predictions that will help communities and various levels of government adapt to climate change.******