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

北极系统可以被看作是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，整个北极系统最完整的组成部分是其气候系统。气候系统的平均状态、变率和变化对生物过程和人类活动有很强的控制作用。北极气候反过来又与全球系统紧密相连。这是一项对北极气候系统的综合研究，它将通过ARCSS和其他国家和国际努力收集的大量数据提炼成一个易于处理的综合热收支框架。虽然北极气候系统肯定是复杂的，但在最基本的意义上，它有一个优雅的简单性。我们可以把这个系统看作是一个极冠，由一个假设的70 oN的壁面定义，并包括两个由表面界面分开的柱体--一个从表面延伸到大气顶部的大气柱体，和一个从表面向下延伸到一定深度的下层柱体。大气柱热含量的变化取决于进入柱体两侧的净能量通量（来自低纬度的热通量）、柱体顶部的辐射收支以及通过表面界面的净热传递。后者包括海冰生长和融化以及感热交换等过程。类似地，下层柱通过流入其侧面的通量以及通过表面界面与大气的连通来获得或损失热量。观测到的北极气候系统的平均年周期、变率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、大气和海洋上层温度、积雪和海冰状况等熟悉的气候要素中。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优点是它提供了一个共同的框架，可以吸收来自许多来源的数据，包括大气再分析，来自耦合的冰-海洋，陆地表面和全球气候模式，卫星遥感，地面和海洋观测。不同的资料来源将对某一预算期作出不同的实现。这种认识的分散代表了一种不确定性。该小组将为包括北冰洋和陆地流域在内的一个领域编制网格化的每月预算时间序列，强调1979年至今的数据丰富时期。考虑到某些记录的局限性（例如，观测到的海洋热传输），他们还将发展更简单领域的气候学。这些数据集将应用于围绕关键研究问题开展的一系列研究，以澄清影响北极气候系统年周期、变率和近期变化的相互作用。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.