Collaborative Research: Understanding Change in the Climate and Hydrology of the Arctic Land Region: Synthesizing the Results of the ARCSS Fresh Water Initiative Projects

北极的气候正在发生变化。根据北极气候影响评估(ACIA)，“北极气候现在正在迅速变暖，预计会有更大的变化”。这些变化令人担忧，因为它们可能对全球海洋环流产生影响。Arcs淡水综合研究旨在解决与北极淡水循环，特别是陆地淡水循环有关的许多更广泛问题的科学基础。特别是，森林倡议的目标是解决“……关键的、悬而未决的问题……从根本上讲，这些问题是跨学科和综合性的”。这些问题中有三个直接涉及北极气候以及该区域的水和能源平衡的双重影响。NSF在2002年资助了一组18个FWI项目，这些项目与随后的ARCS项目一起旨在解决上文概述的FWI问题。然而，需要开展综合活动，以便更充分地利用第一次世界大战项目的成果。这项工作将利用具有大量陆地表面活动的第一次世界大战项目的研究成果，并将把这些成果纳入一项综合活动，该活动将记录观察到的北极水文循环的变化，并将其归类于该区域的气候和全球气候系统。主要的综合机制将是一个耦合的区域陆地-大气模式(极地WRF或MM5)，以及(更有限的使用)一个中等复杂性的海洋-陆地-大气系统的全球模式。要解决的首要科学问题是：北极陆地过程的变化如何影响该地区的气候，这些变化对北极水文循环(包括与大气的耦合和反馈)有什么影响，以及北极淡水系统的变化对全球气候有什么影响？这项研究将解决两个支持性的科学问题：1)如何利用第一次世界大战的研究结果更好地了解影响泛北极陆地系统淡水平衡观测变化的水文过程？2)观测到的北极陆地水文循环的变化在多大程度上是由于从其他区域(通过大气过程)输入的变化，以及观测到的陆地水文变化在多大程度上输出到大气和全球海洋系统？第一个问题引出了关于哪些水文过程对观测到的变化做出了贡献的归属问题，并将使用泛北极尺度上非耦合、部分耦合和完全耦合的陆地-大气模拟战略加以解决。解决第二个问题需要记录水文变化对全球气候的影响(通过海洋变化)。它将通过使用一个中等复杂性的全球陆地-海洋-大气耦合模式(维多利亚大学ESCM气候模式)来解决。到目前为止，我们对北极地区的变化及其在全球气候中更广泛的作用的了解有限。这项研究力求全面了解北极系统内的主要水文过程，以及这些过程如何通过海洋和大气路径在区域范围内与全球系统相互作用。预期这将有助于更好地了解水文过程如何对观测到的变化作出贡献，以及北极以外过程的贡献。对这些相互作用和反馈的详细分析将为气候界了解北极在气候变化和变化中的作用提供有价值的信息。

The climate of the Arctic is changing. According to the Arctic Climate Impact Assessment (ACIA), "Arctic climate is now warming rapidly, and much larger changes are projected". These changes are of concern because of their possible implications for global ocean circulation. The ARCSS Freshwater Integration Study (FWI) was designed to address the scientific basis of many of these broader issues that are related to the arctic freshwater cycle, especially over land. In particular, FWI has the objective of addressing "... key, unresolved issues ... [that are] fundamentally cross-disciplinary and synthetic in nature". Three of these issues deal directly with the coupled implications of arctic climate and the water and energy balances of the region. NSF funded a group of 18 FWI projects in 2002, which together with subsequent ARCSS projects were intended to address the FWI questions outlined above. However there is a need for synthesis activities to exploit more fully results of the FWI projects. This work will utilize research results from the FWI projects that have a substantial land surface activity, and will incorporate the results in a synthesis activity that will document and attribute observed change in the arctic hydrologic cycle, both for the climate of the region, and the global climate system. The primary synthesis mechanism will be a coupled regional land-atmosphere model (either polar WRF or MM5), and (more limited use) of a global model of medium complexity of the ocean-land-atmosphere system. The overarching science question to be addressed is: How do changes in arctic land processes affect the climate of the region, what are the implications of these changes for the arctic hydrologic cycle (including coupling and feedbacks with the atmosphere), and what are the impacts of changes in the arctic freshwater system on global climate?The research will address two supporting science questions: 1) How can the results from the FWI studies be used to better understand the hydrologic processes affecting observed change in the freshwater balance of the pan arctic land system? and 2) To what extent are the observed changes in Arctic terrestrial hydrologic cycle due to imported change from other regions (via atmospheric processes), and to what extent are the observed terrestrial hydrologic changes exported to the atmosphere and to the global ocean system? The first question leads to attribution questions regarding which hydrologic processes have contributed to observed change, and will be addressed using a strategy of uncoupled, partially coupled, and fully coupled land-atmosphere modeling at the pan-arctic scale. Addressing the second question will require documenting the effect of hydrologic change on global climate (via changes in the oceans). It will be addressed through use of a coupled GLOBAL land-ocean-atmosphere model of medium complexity (University of Victoria ESCM climate model).To date our understanding of change in the Arctic region and its broader role in global climate has been limited. This research seeks to provide a comprehensive view of key hydrological processes within the Arctic system and how they interact regionally and with the global system via oceanic and atmospheric pathways. It is expected that this will result in a better understanding of how hydrologic processes have contributed to observed change and the contribution from extra-Arctic processes. Detailed analysis of these interactions and feedbacks will provide valuable information to the climate community for understanding the role of the Arctic in climate variability and change.