Characterization of Atmospheric Moisture Transport and the Freshwater Budget of the Arctic with an Improved Regional Model

[01:80 . 18]北极盆地淡水收支的变化对北冰洋环流和海冰有潜在的巨大影响，而这反过来又与全球海洋环流和气候相耦合。然而，北极淡水收支的大气成分特征相对较差，难以模拟。该项目将利用最先进的计算方法来改进北极大气淡水收支的气候模拟。高纬度数值模拟困难的突出方面是必须充分模拟的极端尺度范围。水分过程的建模需要在小空间尺度上适当地处理相互作用。相比之下，大量观测研究表明，北极气候变率受年代际时间尺度和行星空间尺度的支配。这些要求需要在时间和空间尺度之间进行权衡，由于计算稳定性的限制，目前的欧拉建模方法无法轻易解决。本研究将在一个完全耦合的大气-海洋-海冰模式的背景下实现状态和动力大气变量的半拉格朗日输运。这一新的实施将允许对北极气候进行高分辨率的完全耦合的长期模拟，并增加对大气水文循环关键组成部分的不确定性分析的集合技术的使用。模型实验将用于解决以下主要研究问题：1。北极水文循环对模拟大气环流变率的敏感性是什么？北半球半年振荡在多大程度上影响地表水分通量和/或大气水分输送？什么因素影响北极半年振荡的年际变化和趋势？异常海冰和/或积雪对随后季节大气水分收支的影响是什么？冬季气候指数的异常是否会转化为其他季节的异常降水？在大气湿度变量中可以确定北极气候的哪些夏季或全年结构？陆地上的大气对流在夏季北极水文循环中起重要作用吗？

0138018SerrezeChanges in the freshwater budget of the Arctic Basin have potentially large impacts on the circulation and sea ice of the Arctic Ocean, which is in turn coupled to the global ocean circulation and climate. However, the atmospheric components of the arctic freshwater budget are characterized relatively poorly and difficult to model. This project will utilize state-of-the-art computational methods to improve climatological simulations of the atmospheric freshwater budget of the Arctic.The salient aspect of high latitude numerical modeling difficulties is the extreme range of scales that must be simulated adequately. Modeling moisture processes requires appropriate treatment of interactions at small spatial scales. By contrast, numerous observational studies have suggested that arctic climate variability is dominated by decadal time scales and planetary spatial scales.These requirements necessitate a trade-off between temporal and spatial scales that cannot be addressed readily with current Eulerian modeling methods, due to computational stability constraints. This study will implement semi-Lagrangian transport for state and dynamical atmospheric variables within the context of a fully coupled atmosphere-ocean-sea ice model. This new implementation would allow both long-term simulations of the fully coupled arctic climate at high resolution, as well as increased use of ensemble techniques for an uncertainty analysis of crucial components of the atmospheric hydrologic cycle. Model experiments will be used to address the following primary research questions:1. What is the sensitivity of the arctic hydrologic cycle to variability in the simulated atmospheric circulation?2. To what extent does the Northern Hemisphere semiannual oscillation influence surface moisture fluxes and/or atmospheric moisture transport? What factors influence interannual variability and trends in the arctic semiannual oscillation?3. What is the influence of anomalous sea ice and/or snow cover on the atmospheric moisture budget over subsequent seasons? Do anomalies in wintertime climate indices translate into anomalous precipitation in other seasons? What summertime or year-round structures in the arctic climate can be identified in atmospheric moisture variables?4. Does atmospheric convection over land play a significant role in the arctic hydrologic cycle during the summer season?