Collaborative Research: Combined Influence of Snow Cover and El Nino/Southern Oscillation (ENSO) on North African/Mediterranean Temperature and Precipitation

合作研究：积雪和厄尔尼诺/南方涛动（ENSO）对北非/地中海气温和降水的综合影响

• 批准号: 1303542
• 负责人: Jeffrey Shaman
• 金额: $ 36.98万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-12-01 至 2017-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1303542&HistoricalAwards=false
• 关键词: Collaborative; Research; Combined; Influence; Snow

This project considers the generation of North African and Mediterranean climate anomalies by El Nino/Southern Oscillation (ENSO) events and Eurasian snow cover fluctuations. Two causal mechanisms are examined, one involving tropospheric teleconnections produced by Rossby wave generation and propagation (a "horizontal" mechanism), and the other involving stratosphere-troposphere interactions (a "vertical" mechanism). The horizontal mechanism is hypothesized to consist of 1) a canonical northeastward propagating wave train that emanates from the eastern equatorial Pacific, and 2) an ultra-low frequency Rossby wave that is excited over the Pacific, trapped within the North African-Asian (NAA) jet and propagates upstream to the Mediterranean region. The vertical mechanism begins with an expansion of Eurasian snow cover, which leads to colder surface conditions and lowering of mid-tropospheric geopotential height. This in turn amplifies the wave-1 stationary wave pattern, which propagates into the stratosphere and reduces the strength of the polar vortex, resulting in a negative anomaly of the Arctic or North Atlantic Oscillation, which shifts the jet stream and storm track southward. The southward shift of the jet and storm track allows colder temperatures to invade the middle latitudes, including the Mediterranean region. These influences will be examined through statistical analysis combined with a suite of models including a Rossby wave ray tracing calculation, a linearized barotropic model, a state-of-the-art global atmospheric model (CAM), and an atmospheric model with a well-resolved stratosphere (WACCM). In addition, an empirical prediction scheme will be developed and tested using Eurasian snow cover and ENSO as predictors for seasonal Mediterranean precipitation and surface temperature.The work has societal broader impacts due to the agricultural and other consequences of climate variability in the Mediterranean region. More specifically, the empirical prediction scheme will be provided to operational centers including the International Research Institute at Columbia University. In addition, a website will be developed to provide public information regarding the role of atmospheric teleconnections in producing climate anomalies. The project will also support and train a graduate student, thereby providing for the future scientific workforce in this research area.

该项目考虑了El Nino/Southern Oscillation（ENSO）事件的北非和地中海气候异常的产生，欧亚降雪涵盖了波动。检查了两种因果机制，一种涉及由Rossby波产生和传播产生的对流层遥控物（一种“水平”机制），另一个涉及涉及平流层 - 对流层相互作用（一种“垂直”机制）。 假设水平机制由1）从东部赤道太平洋散发出的规范向东北传播波列，以及2）一个超低的频率rossby波，它被困在太平洋上，被困在太平洋，在北非亚洲（NAA）中，并向地中海地区向上传播到地中海地区。垂直机制始于欧亚积雪的扩展，这导致表面条件较冷，并降低了对流层地球电位高度的降低。反过来，这放大了波浪1固定波模式，该波段传播到平流层并降低了极性涡流的强度，从而导致北极或北大西洋振荡的负异常，从而将喷气流和风暴轨道向南移动。喷气式和风暴轨道的南移允许较冷的温度入侵中纬度，包括地中海地区。 这些影响将通过统计分析与包括Rossby Wave射线追踪计算，线性的正压模型，最先进的全球大气模型（CAM）以及具有良好分辨平流层（WACCM）的大气模型相结合来检查这些影响。 此外，将使用欧亚积雪和ENSO作为季节性地中海降水和表面温度的预测者制定和测试经验预测方案。由于地中海地区气候变化的农业和其他后果，这项工作对社会产生了更大的影响。 更具体地说，将向包括哥伦比亚大学国际研究所在内的运营中心提供经验预测计划。 此外，将开发一个网站，以提供有关大气远程连接在生产气候异常中的作用的公共信息。 该项目还将支持和培训一名研究生，从而为该研究领域提供未来的科学劳动力。