NSFGEO-NERC:Large-Scale Atmospheric Circulation Response to Oyashio Extension Frontal Variability

这份提交给美国国家科学基金会地球科学理事会和英国自然环境研究委员会的联合提案旨在调查西北太平洋的洋潮延伸锋面变化是如何通过积累单个天气系统和底层海洋锋面之间的相互作用来影响大尺度大气环流的。大气风暴路径在西北太平洋表现出局部最大强度，在由最大斜压性驱动的强洋锋上方，而最大斜压性又由海洋提供的大量热量和水分维持。虽然在过去十年左右的时间里，我们对海洋锋面对大气平均气候的影响的理解取得了重大进展，但仍有许多关键问题尚未得到回答，特别是与海洋锋面变率对大气环流变率的影响有关。本研究的一个特别目标是揭示在大尺度大气环流和气候变率的累积影响中，在天气尺度上的本地海气相互作用及其与大尺度大气环流和气候变率之间的联系。通过对比初冬和晚冬的季节特征，以及大尺度大气响应的不对称性/非线性，将重点放在这一联系的季节性上，这些响应分别是由亲潮伸展锋向北和向南移动引起的温暖和寒冷海温异常。这些具有挑战性的目标将通过结合观测和再分析数据集的分析以及使用可变分辨率社区大气模式v.6和光谱元素动态核心（一种最先进的大气环流模式）的有针对性的气候模式实验来解决。该系统将在北太平洋上空配置非常高的分辨率，在全球其他地方配置较低的分辨率，以真实地模拟在大潮延伸上空的锋面空气-海面相互作用，以及在可控的计算成本下与大规模环流的反馈。此外，将通过比较仅大气模拟与一维柱状海洋模式耦合的模拟来研究局部海洋耦合的作用。

This joint proposal to U.S. National Science Foundation's Directorate for Geosciences and U.K. NaturalEnvironment Research Council aims to investigate how the Oyashio Extension frontal variability in theNorthwest Pacific Ocean influences the large-scale atmospheric circulation by accumulating theinteraction between the individual weather system and underlying ocean front. The atmospheric stormtrack exhibits the local maximum strength in the Northwest Pacific over the strong ocean fronts driven bycollocated maximum baroclinicity, which is in turn maintained by huge heat and moisture supplied by theocean. While significant advances have been achieved in the past decade or so on our understanding ofocean front's impact on the atmosphere for the mean climate, there are still many crucial questions yet tobe answered, especially related to impact of ocean frontal variability on the atmospheric circulationvariability. A particular goal of this proposal is to unveil the link between the local air-sea interaction inweather scale near the Oyashio Extension and its cumulative impact on the large-scale atmosphericcirculation and climate variability. Specific emphases will be placed on the seasonality of this link bycontrasting the early and late winter, and also the asymmetry/nonlinearity in the large-scale atmosphericresponse to warm and cold SST anomalies induced by a shift of the Oyashio Extension front to the northand south, respectively. These challenging goals will be addressed by combining analyses ofobservational and reanalysis datasets and targeted climate model experiments using the VariableResolution Community Atmosphere Model v.6 with Spectral Element dynamical-core, a state-of-the artatmospheric general circulation model, which will be configured with a very high-resolution over theNorth Pacific and lower resolution elsewhere globally to realistically simulate the frontal air-seainteraction over the Oyashio Extension as well as the feedback with the large-scale circulation at amanageable computational cost. Furthermore, the role of local ocean coupling will be investigated bycomparing the atmosphere-only simulations with those coupled to the 1-dimensional column oceanmodel.