Collaborative Research: Type 1 - Improved Cold Region Hydrology Process Representation as a Cornerstone of Arctic Biogeochemical Modeling (L02170157)

北极目前正在经历快速的环境变化，例如，广泛的永久冻土融化和相关的热岩溶启动，湖泊分布的变化，植被群落组成的变化，以及许多其他生态系统过程的变化。与冰和水之间的相变相关的阈值和非线性响应使北极特别容易受到迅速和破坏性变化的影响。认识到变化的范围及其速度，引起了人们的关注，即储存在受永久冻土影响的土壤和泥炭地土壤中的大量、直到最近还处于有效休眠状态的土壤碳库可能比以前认为的更脆弱。北极碳循环的命运从根本上取决于现在和未来的土壤水文状态。科学界迫切需要能够评估和量化这种碳是否是一种？北极的碳定时炸弹？或者其他生物地球物理和生物地球化学反馈是否会限制或减轻永久冻土融化时大量的碳释放。综合地球系统模式（ESMs），如社区地球系统模式（CESM），需要评估北极和全球对北极陆地变化的综合响应。尽管CESM陆地模型在冻土、生物地球化学循环和北极植被演替方面取得了最新进展，但目前寒区水文的表示不足以对北极冻土碳问题进行全面研究。为了解决这一限制，我们提出了一项有针对性的努力，以改善CESM中的北极陆地水文过程，并使用由此产生的模型来评估最近和未来十年尺度的北极水文变化。该项目的顺利完成将为全面评价北极陆地生物地球化学反馈提供基础。

The Arctic is currently experiencing rapid environmental change, for example, widespread permafrost thaw and associated thermokarst initiation, changes in lake distribution, shifts in vegetation community composition, as well as changes in a host of other ecosystem processes. Threshold and non-linear responses associated with phase change between ice and water leave the Arctic particularly susceptible to swift and disruptive change. Realization of the scope of change, in conjunction with its pace, has spawned  concern that the massive and, until recently, effectively dormant soil carbon pools stored in permafrost-affected and peatland soils may be more vulnerable than previously thought. The fate of the Arctic carbon cycle is fundamentally governed by present and future soil hydrologic states.  There is an urgent need for the scientific community to be able to assess and quantify whether or not this carbon is an ?Arctic carbon time bomb?, as it is sometimes colloquially referred to, or if other biogeophysical and biogeochemical feedbacks will restrict or mitigate a substantial carbon release as permafrost thaws. Comprehensive Earth System Models (ESMs), such as the Community Earth System Model (CESM), are required to assess the integrated Arctic and global response to terrestrial Arctic change.  Though recent advances in the land model of CESM have been made with respect to the representation of permafrost, biogeochemical cycles, and Arctic vegetation succession, the current representation of cold region hydrology is inadequate to permit a holistic study of the Arctic permafrost carbon problem.  To address this limitation, we propose a targeted effort to improve Arctic terrestrial hydrological processes in the CESM and to use the resulting model to assess recent and future decadal-scale Arctic hydrology change.  The successful completion of this project will provide the foundation for a thorough evaluation of the Arctic terrestrial biogeochemical feedbacks.