Modulation of El Niño Southern Oscillation and its impacts by the mean climate state

厄尔尼诺南方涛动的调节及其平均气候状态的影响

• 批准号: 2296358
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2296358
• 关键词: Modulation; El; Ni; Southern; Oscillation

The El Niño Southern Oscillation (ENSO) is the leading mode of interannual climate variability in the tropics and affects regional climates around the globe. During ENSO events, changes to atmospheric circulation and precipitation patterns in response to perturbed sea surface temperature lead to remote climate effects that vary regionally and by season. Internal modes of interannual climate variability such as the Pacific Decadal Oscillation (PDO) and the Atlantic multidecadal variability (AMV), along with anthropogenic sources of radiative forcing (eg. greenhouse gases emission and aerosol concentration) alter the global climate circulation on interannual and decadal timescales and therefore must be included in the study of ENSO impacts under future climate conditions.A largely unexplored research area is whether the effects of ENSO events on climate extremes may change in a future, warmer climate. Climate change may affect both the frequency of climate extremes, increasing the variance, and the mean, changing the shape of the distribution of a certain variable in the future (Lavell et al., 2012). In a warmer climate, the increase in atmospheric moisture may intensify the variability in precipitation associated with ENSO (Christensen et al., 2013). However, generally few attempts have been made to examine the specific contribution of ENSO to changing extremes. The latest climate model simulations encompassed in the Climate Model Intercomparison Model Phase 6 (CMIP6) will mean significant improvements in the representation of ENSO (Collins et al., 2014). A especial focus of the project will be on evaluating the influence of the North Atlantic mean state on ENSO and its climate impacts. This will be addressed by contrasting ENSO impacts between simulations in which the North Atlantic SST will be constraint to warm or cold conditions. Recent literature suggests that Atlantic multidecadal variability (AMV) can modify the tropical Pacific mean state (McGregor et al., 2014, Li et al., 2016, Ruprich-Robert et al., 2017). However, it is still not clear how those changes in the Pacific mean state translate into changes of ENSO behaviours (e.g. Wang et al., 2017). In addition, recent studies suggested that the AMV can also influence ENSO teleconnections even without changing ENSO itself (Lopez-Parages et al., 2015). A better understanding of the AMV influences on ENSO and its teleconnections will increase the level of confidence of extreme impacts assessments and seasonal forecasts.The specific objectives of the project are: 1. Investigate ENSO and its impacts from different model resolutions. In particular, contrasting these in low and high resolution simulations, including those performed within the High Resolution Model Intercomparison project (HighResMIP) and other very high resolution simulations performed by BSC. This approach represents a great advantage in terms of high-resolution runs that will allow to assess small-scale climate impacts.2. Evaluate the influence of different mean states on ENSO and its impacts (including precipitation and temperature extremes) by comparing simulated ENSO impacts from present day with end of 21th century simulations.3. Assess ENSO impacts with different North Atlantic background conditions using the Decadal Climate Prediction Project (DCPP) Component C experiments of CMIP6.4. Determine relationships between ENSO and different anthropogenic forcing levels from step change perturbation experiments.5. Determine the most vulnerable regions to future ENSO events and make an impact assessment of extremes.

厄尔尼诺南部振荡（ENSO）是热带气候际气候变化的领先模式，并影响全球周围的区域气候。在ENSO事件中，大气循环和降水模式的变化响应于扰动的海面温度会导致偏远的气候效应在区域和季节变化。年际气候变化的内部模式，例如太平洋decadal振荡（PDO）和大西洋多阶段可变性（AMV），以及辐射强迫的人为来源（例如，温室气体的排放和气雾剂浓度）在全球气候循环中都必须在全球气候循环中对间歇性和十年型的造成影响，以及对年间气候循环的影响。在很大程度上，意外的研究领域是ENSO事件对极端气候的影响是否可能在未来的气候变暖中发生变化。气候变化可能会影响气候极端的频率，增加了方差，含义会改变未来某个变量的分布形状（Lavell等，2012）。在温暖的气候下，大气水分的增加可能会加剧与ENSO相关的降水的变化（Christensen等，2013）。但是，通常很少尝试研究ENSO对改变极端的特定贡献。气候模型对比模型6（CMIP6）中包含的最新气候模型模拟将意味着ENSO表示的显着改善（Collins等，2014）。该项目的特别重点将是评估北大西洋平均国家对ENSO及其气候影响的影响。这将通过对比的ENSO影响在北大西洋SST对温暖或寒冷条件的模拟之间的对比来解决。最近的文献表明，大西洋多阶段变异性（AMV）可以改变热带太平洋平均状态（McGregor等，2014，Li et al。，2016； Ruprich-Robert等，2017）。但是，仍然不清楚太平洋平均状态中的这些变化如何转化为ENSO行为的变化（例如Wang等，2017）。此外，最近的研究表明，即使不改变ENSO本身，AMV也会影响ENSO远程连接（Lopez-Parages等，2015）。更好地了解AMV对ENSO及其遥相关的影响将提高极端影响评估和季节性预测的信心水平。该项目的具体目标是：1。研究ENSO及其对不同模型分辨率的影响。特别是，将它们与低分辨率模拟进行对比，包括在高分辨率模型对比项目（HighResmip）和BSC执行的其他非常高分辨率的模拟中进行的。在高分辨率运行方面，这种方法是一个很大的优势，可以评估小规模的气候影响。2。通过比较当今的模拟ENSO影响与21世纪末模拟3。使用CMIP6.4的decadal气候预测项目（DCPP）组件C实验，以不同的北大西洋背景条件评估ENSO的影响。确定ENSO与不同人为强迫水平之间的关系。确定对未来ENSO事件的最脆弱区域，并对极端进行影响评估。