Collaborative Research: Snowpack Energy and Mass Balance: Implications for Biogeochemical Feedbacks in Alpine Basins

积雪能量和质量平衡：阿尔卑斯山盆地生物地球化学反馈的含义？加州大学洛杉矶分校合作伙伴？s：T. Meixner？联合亚利桑那州; J·西克曼？加州大学滨江分校; M.威廉姆斯？联合由于氮地球化学和水文模型耦合的困难，对氮地球化学的水文强迫作用知之甚少。 长期集水研究在内华达州和落基山脉表明，N循环在高山系统的积雪动态的强烈影响，但这种控制的机制仍然不明确。 大气环流模式表明，在未来世纪，气温的上升将导致山区积雪和融化的数量和速度发生重大变化。 与此同时，山？热点？在逆风，低海拔地区的人为N排放的局部影响。 考虑到气候变化和氮沉积速率，对山区生态系统和水供应的影响可能是非线性的，如果没有详细的机械模型，就不可能预测。 这项研究将填补这一关键的知识空白，量化之间的关系，在融雪，水文途径和停留时间，和N循环的变化。 通过将卫星对雪特性的观测与耦合水文和地球化学过程的模型相结合，我们将更广泛地了解这些过程的敏感性以及对气候变率和变化的反馈。 15年的回顾性分析和未来的气候情景将用于评估以下问题：1）气候变率如何影响雪-大气能量交换和融雪的速度和空间格局？2)气候的年际变化如何影响水文水流路线和水化学通量？3)在未来的气候情景下，水文和元素通量之间的联系将如何变化？这些问题将在美国两个研究得最好的山区研究地点-加州内华达州谢拉的托科帕分水岭和科罗拉多落基山脉前岭的绿色湖谷-得到解决。 流路模型内的融雪空间显式表示将提高对控制高山系统水化学通量的过程的理解。 未来的气候情景将利用这些进展来确定高山系统对未来世纪的间歇性和慢性酸化的敏感性。

Snowpack Energy and Mass Balance: Implications for Biogeochemical Feedbacks in Alpine BasinsPI: Noah Molotch ? UC Los AngelesCo-PI?s: T. Meixner ? U. Arizona; J. Sickman ? UC Riverside; M. Williams ? U. ColoradoAbstractHydrologic forcing of nitrogen (N) biogeochemistry is poorly understood due to difficulties in coupling biogeochemical and hydrologic models. Long-term catchment studies in the Sierra Nevada and Rocky Mountains demonstrate that N cycling in alpine systems is strongly influenced by snowpack dynamics, but mechanisms underlying this control remain undefined. General circulation models indicate that increasing air temperature over the coming century will cause substantial changes in the amounts and rates of snow accumulation and melt in mountainous regions. At the same time, mountains are ?hot-spots? for localized impacts from anthropogenic N emissions in upwind, lower-elevation areas. Given both changing climate and N deposition rates, impacts to mountain ecosystems and water supplies are likely to be non-linear and impossible to predict without detailed mechanistic models. This study will fill this critical gap in knowledge by quantifying relationships among variability in snowmelt, hydrologic pathways and residence times, and N cycling. By merging satellite observations of snow properties with models that couple hydrological and biogeochemical processes we will gain broader understanding of the sensitivity of these processes and feedbacks to climate variability and change. Fifteen-year retrospective analyses and future climate scenarios will be used evaluate the following questions: 1) How does climate variability influence snow-atmosphere energy exchange and the rate and spatial patterns of snowmelt?2) How does inter-annual variability in climate impact hydrologic flow routing and hydrochemical fluxes?3) How will linkages between hydrologic and elemental fluxes change under future climate scenarios?These questions will be addressed in two of the best-studied mountain research sites in the United States - the Tokopah watershed in the Sierra Nevada, California and the Green Lakes Valley in the Rocky Mountain Front Range of Colorado. The spatially explicit representation of snowmelt within flow-path models will improve understanding of the processes that control hydrochemical fluxes of alpine systems. Future climate scenarios will leverage these advances to determine the susceptibility of alpine systems to episodic and chronic acidification for the coming century.