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

北冰洋盆地淡水预算的变化对北冰洋的环流和海冰有潜在的重大影响，而北冰洋的影响又与全球海洋环流和气候有关。然而，北极淡水收支的大气组成部分的特点相对较差，很难建立模型。该项目将利用最先进的计算方法来改进对北极大气淡水收支的气候学模拟。高纬度数值模拟困难的突出方面是必须充分模拟极端范围的尺度。对水分过程进行建模需要适当处理小空间尺度上的相互作用。相比之下，大量的观测研究表明，北极气候的可变性是由十年时间尺度和行星空间尺度主导的。这些要求需要在时间和空间尺度之间进行权衡，而由于计算稳定性的限制，目前的欧拉模型方法不能很容易地解决这一问题。这项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送。这一新的实施将允许以高分辨率对完全耦合的北极气候进行长期模拟，以及更多地使用集合技术对大气水文循环的关键组成部分进行不确定性分析。模式试验将被用来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化的敏感性如何？2.北半球半年振荡对地表水汽通量和/或大气水汽输送的影响有多大？影响北极半年振荡年际变化和趋势的因素是什么？3.异常的海冰和/或积雪覆盖对随后几个季节的大气水分收支有什么影响？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夏季或全年结构是什么？4.陆地上的大气对流在夏季期间的北极水文循环中是否起着重要作用？

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?