Mechanisms of Mediterranean Region Hydroclimate Variability and Change

干旱长期以来一直是地中海周边国家的担忧，从伊比利亚半岛到北部的土耳其，从摩洛哥到南部沿着叙利亚。 该地区的大部分地区在世纪后半叶经历了长期干旱，最近叙利亚的动荡是在新月沃地发生了特别严重的干旱之后。 此外，气候模式在预测21世纪世纪地中海周围强烈的干旱趋势方面非常一致。该项目旨在了解驱动地中海地区降水和蒸发的自然变率和强迫变化的动力机制。 通过使用基于树木年轮的气候重建，观测记录得到了扩展，为近几十年的干旱提供了长期背景。 其他工作考虑了地中海气旋在区域降水变化中的作用，沿着气旋行为的变化可能有助于气候模型中看到的未来干旱。 喷射流的作用，在未来的干燥转移检查使用线性驻波模型和其他诊断技术。 一个彻底的水分收支分析进行了使用基于观测的再分析产品和气候模式输出。 以前的工作表明，地中海的水文气候变化大部分与北大西洋涛动有关，这涉及大西洋急流和风暴轨迹的南北转移。 研究所的初步工作表明，这种变异性可以与气候变暖导致的干旱区分开来。 这项工作还包括努力开发地中海水文气候的概率预测，考虑到模型在模拟过去的variability.As上面指出的技能，这项工作具有很大的社会意义，由于人类的影响广泛的干燥和有点可怕的模型预测未来地中海干旱。 这些预测似乎是可信的，因为它们在不同的模型之间具有一致性，但是在长期气候记录的背景下对潜在机制进行审查，可以大大有助于评估其有效性。 PI通过MedCLIVAR参与地中海气候并影响社区，MedCLIVAR是一个研究协调网络，其活动包括以地中海气候为重点的研讨会，学校和交流计划。 在离家更近的地方，该项目通过拉蒙暑期实习生项目与本科生接触，并通过一年两次的拉蒙开放日进行外联。 该项目还为博士后研究学者提供支持和培训，从而发展这一研究领域的劳动力。

Drought has long been a concern for the countries surrounding the Mediterranean, from the Iberian Peninsula to Turkey on the north and from Morocco to Syria along the southern shore. Much of the region experienced prolonged drying in the second half of the 20th century, and the recent turmoil in Syria follows a particularly acute drought in the Fertile Crescent. Moreover, climate models are remarkably consistent in projecting a strong drying trend around the Mediterranean over the 21st century.This project seeks to understand the dynamical mechanisms that drive natural variability and forced change in precipitation and evaporation over the Mediterranean region. The observational record is extended through the use of tree ring - based climate reconstructions to give long-term context to the drying of recent decades. Other work considers the role of Mediterranean cyclones in regional precipitation variability, along with changes in cyclone behavior that may contribute to the future drying seen in climate models. The role of jet stream shifts in future drying is examined using a linear stationary wave model and other diagnostic techniques. A thorough moisture budget analysis is carried out using both observationally-based reanalysis products and climate model output. Previous work shows that much of the hydroclimate variability in the Mediterranean is linked to the North Atlantic Oscillation, which involves a north-south shift of the Atlantic jet stream and storm track. Preliminary work by the PIs suggests that this variability can be distinguished from aridity occurring as a consequence of a warming climate. The work also includes an effort to develop probabilistic projections of Mediterranean hydroclimate that take into account the skill of models in simulating past variability.As noted above, the work has great societal relevance due to the human impacts of widespread drying and the somewhat dire model projections of future Mediterranean aridity. The projections are plausible given their consistency from one model to another, but an examination of the underlying the mechanisms, in the context of a long-term climate record, can do much to assess their validity. The PIs engage with the Mediterranean climate and impacts communities through MedCLIVAR, a research coordination network which conducts activities including workshops, schools, and exchange programs focused on Mediterranean climate. Closer to home, the project engages with undergraduate students through the Lamont Summer Intern Program and conducts outreach through the biannual Lamont Open House. The project also provides support and training for a postdoctoral research scholar, thereby developing the workforce in this research area.