Collaborative Research: A Heat Budget Analysis of the Arctic Climate System

摘要北极系统可以被视为一组相互联系和相互作用的物理、生物和人类组成部分。可以说，整个北极系统中最完整的组成部分是它的气候系统。气候系统的平均状态、变异性和变化对生物过程和人类活动具有很强的控制作用。北极气候反过来又与全球系统紧密相连。这是一项旨在综合北极气候系统的努力，该系统将通过ARCS和其他国家和国际努力收集的丰富数据提取到一个易于处理的、整合的热量预算框架中。尽管北极气候系统当然是复杂的，但在其最基本的意义上，它具有优雅的简单性。人们可以从极地帽的角度来考虑这个系统，极帽由北纬70o度的假想墙定义，由地面界面分隔的两个柱组成--一个大气层柱从地面延伸到大气层顶部，以及一个底层柱，从地面向下延伸到一定深度。大气柱热含量的变化取决于进入其两侧的净能量通量(来自较低纬度的热通量)、其顶部的辐射平衡以及通过地面界面的净热量传输。后者包括海冰生长和融化以及感热交换等过程。同样，下面的柱子通过进入其侧面的通量获得或失去热量，并通过表面界面与大气进行交流。观测到的北极气候系统的年平均周期、变异性和变化基本上可以用这些相互作用来描述，反映在大气环流、地表、大气和上层海洋温度、积雪和海冰状况等常见气候要素中。虽然上面的例子考虑的是一个简单的极冠，但热量收支框架可以用来理解气候系统的区域方面。这种思维方式的一个好处是，它提供了一个共同的框架，在这个框架内，来自许多来源的数据，包括大气再分析，可以从耦合的冰-海洋、陆地表面和全球气候模式、卫星遥感以及地面和海洋观测中获得。不同的来源会给出不同的预算期限的变现。这种变现的扩散代表了一定程度的不确定性。该小组将为一个包括北冰洋和陆地排水的领域汇编每月预算条款的网格化时间序列，重点是1979年至今的数据丰富时期。鉴于某些记录的局限性(例如，观测到的海洋热传输)，它们还将发展出更简单领域的气候学。这些数据集将被应用于围绕关键研究问题的一系列研究，以澄清影响北极气候系统年度周期、可变性和最近变化的相互作用。他们还将评估系统最近的变化和预测的未来状态之间的一致性。

AbstractThe Arctic System can be viewed as a set of interconnected and interacting physical, biological and human components. Arguably the most integrating component of the full Arctic system is its climate system. The mean state, variability and change in the climate system exert strong controls on biological processes and human activities. Arctic climate is in turn tightly coupled to the global system. This is an effort towards synthesis of the Arctic climate system that distills the wealth of data assembled though ARCSS and other national and international efforts in a tractable, integrating heat budget framework.While the Arctic climate system is certainly complex, in its most fundamental sense it has an elegant simplicity. One can consider the system in terms of a polar cap, defined by a hypothetical wall at 70oN, and comprising two columns separated by the surface interface - an atmospheric column extending from the surface to the top of the atmosphere, and an underlying column, extending from the surface down to some depth. Changes in the heat content of the atmospheric column depend on the net flux of energy coming into its sides (the heat flux from lower latitudes), the radiation budget at its top, and net heat transfers through the surface interface. These latter transfers include processes such as sea ice growth and melt, and exchanges of sensible heat. Similarly, the underlying column gains or loses heat via fluxes into its sides and communication with the atmosphere through the surface interface. The observed mean annual cycle, variability and change in the Arctic climate system can be essentially described in terms of these interactions, reflected in familiar climate elements such as the atmospheric circulation, surface, atmospheric and upper-ocean temperatures, snow cover and sea ice conditions. While the above example considers a simple polar cap, the heat budget framework can be applied to understand regional aspects of the climate system.An advantage of this way of thinking is that it provides a common framework within which data from many sources, including atmospheric reanalyses, runs from coupled ice-ocean, land surface and global climate models, satellite remote sensing, and surface and oceanic observations, can be ingested. Different sources will give different realizations of a given budget term. This spread of realizations represents a measure of uncertainty. This group will compile gridded monthly time series of budget terms for a domain encompassing the Arctic Ocean and terrestrial drainage, emphasizing the data-rich period 1979 to present. Given the limitations of some records (e.g., observed ocean heat transports), they will also develop climatologies for simpler domains. These data sets will be applied in a series of studies, framed around key research questions, to clarify interactions shaping the annual cycles, variability and recent changes in the Arctic climate system. They will also assess consistency between recent changes and projected future states of the system.