Variable Resolution Modeling of the Large-Scale Atmospheric Circulation Response to North Atlantic Sea-Surface Temperature (SST) Anomalies

大尺度大气环流对北大西洋海面温度 (SST) 异常响应的可变分辨率建模

基本信息

批准号：
2128409
负责人：
David Battisti
金额：
$ 34.12万
依托单位：
University of Washington
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-11-15 至 2024-10-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2128409&HistoricalAwards=false
关键词：
Variable Resolution Modeling Large Scale

项目摘要

The extent to which the atmospheric circulation responds to changes in the underlying sea surface temperature (SST) is a central topic in climate dynamics. In the tropics the response of atmospheric circulation to SST variability is easily seen in the evolution of El Nino events. But in the middle and high latitudes there is no comparably strong and unambiguous attribution of circulation change to variations in underlying SST. Nevertheless recent research suggests that SST variability associated with the meandering of the Gulf Stream affects the decade-to-decade variability of the wintertime atmospheric circulation over much of the Northern Hemisphere. The observational evidence is suggestive but not conclusive, as the inherent noisiness of circulation variability and the short length of the observational record do not permit definitive attribution. Climate model simulations offer a way around the shortness of the observed record, along with the ability to design controlled experiments, and models using moderate resolution (say one gridpoint per degree of latitude and longitude) can generate very long simulations. But such simulations have not generally shown a circulation response to Gulf Stream SST variations, and recent experiments suggest that much higher resolutions are necessary to capture the physics and dynamics leading to the circulation response. Unfortunately global simulations using such high resolutions are too computationally intensive to permit in-depth experimentation.Research under this award considers the effects of Gulf Stream SST variations using a variable resolution (VR) model in which the grid spacing over most of the world is one degree but resolution over the Arctic and northern North Atlantic is increased to 1/8th degree, or about 12km between gridpoints. The model is a version of the Community Atmosphere Model (CAM), the atmospheric component model of the Community Earth System Model (CESM). Preliminary results show a robust hemispheric circulation response, with a spatial pattern similar to the North Atlantic Oscillation, forced by an imposed SST change representative of a Gulf Stream fluctuation. Further work compares the VR-CAM simulations with CAM simulations at lower resolution to identify the physics and dynamics captured by the high resolution. One hypothesis is that higher resolution is necessary to capture the influence of SST change on the rising motions associated with frontal weather systems as they cross the Gulf Stream. A further goal of the project is to use machine learning to develop parameterizations of the small-scale effects captured in the VR simulations so that they can be represented approximately at coarser and less computationally intensive model resolutions.The work has societal relevance due to the desirability of better understanding of decade-to-decade changes in the wintertime circulation over the Northern Hemisphere. Recent work suggests that the decadal circulation variabililty is more predictable than would be expected based on climate model simulations, suggesting that models may be missing key ingredients needed for successful long-range predictions. The work performed here may thus contribute to the development of models capable of long-range predictions with substantial societal value. In addition, the project contributes to the development of VR-CAM, which will be made available to the worldwide community of CESM users and developers. The Principal Investigators conduct outreach to the public through the University of Washington Program on Climate Change, as well as the Science Communication Fellowship Program at the Pacific Science Center in Seattle.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

大气循环对基础海面温度（SST）变化的响应程度是气候动力学的中心主题。在热带地区，在El Nino事件的演变中很容易看到大气循环对SST变异性的反应。但是在中间和高纬度地区，循环变化对基础SST的变化没有相当强的且明确的归因。然而，最近的研究表明，与海湾流弯曲有关的SST变异性会影响冬季大气环流的十年到十年的变化。观察性证据是暗示性的，但不是结论性的，因为循环变异性的固有噪声和观察性记录的短长度不允许确切的归属。气候模型模拟提供了一种围绕观察到的记录的短暂性，以及设计受控实验的能力，以及使用中等分辨率（例如每个纬度和经度度的一个网格点）的模型可以产生很长的模拟。但是，这种模拟通常没有显示出对海湾流SST变化的循环响应，并且最近的实验表明，对于捕获导致循环反应的物理和动力学，需要更高的分辨率。不幸的是，使用如此高分辨率的全球模拟在计算上太密集了，无法允许深入实验。在该奖项下，使用可变分辨率（VR）模型来考虑墨西哥湾流SST变化的影响，在世界上，大多数世界上的网格间距是一个程度的一个程度，但分辨率是一个程度上的分辨率，但在北极地区和北部的北部北部地区增加了一个或1/8th to 1/8th to 1/8th的效果。该模型是社区大气模型（CAM）的版本，这是社区地球系统模型（CESM）的大气组件模型。初步结果显示出强大的半球循环响应，其空间模式与北大西洋振荡相似，这是由代表墨西哥湾流动的SST变化强迫的。进一步的工作将VR-CAM模拟与较低分辨率的CAM模拟进行了比较，以识别高分辨率捕获的物理和动力学。一个假设是，必须进行更高的分辨率，以捕获SST变化对跨天气系统越过海湾流时的上升动作的影响。该项目的另一个目标是使用机器学习来开发VR模拟中捕获的小尺度效果的参数化，以便可以大约以更粗糙的计算密集型模型分辨率来表示它们，这项工作具有社会相关性。由于可以在冬季越过北半球的冬季循环中更好地理解十年到十分纪念日的变化，因此具有社会相关性。最近的工作表明，基于气候模型模拟，衰老的循环变化比预期的更为可预测，这表明模型可能缺少成功的长期预测所需的关键成分。因此，这里执行的工作可能有助于开发能够具有实质性社会价值的远程预测的模型。此外，该项目为VR-CAM的开发做出了贡献，VR-CAM将提供给CESM用户和开发人员的全球社区。首席研究人员通过华盛顿大学气候变化计划以及西雅图太平洋科学中心的科学传播奖学金计划向公众进行宣传。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估来通过评估来支持的。