The Origin and Structure of the Monsoon Onset Vortex

阿拉伯海上空的两个事件是印度夏季风的明显前兆：海面温度升高的“迷你暖池”的形成，以及从东非海岸到印度西海岸的索马里低空急流的延伸。急流将从温暖的阿拉伯SST蒸发的水分带到印度沿海，引发季风，并且在许多年中季风爆发伴随着被称为季风爆发涡（MOV）的气旋性涡旋。 MOV的重要性不仅在于它与季风爆发的关系，还在于它可以演变成台风并在登陆时造成广泛的破坏。该奖项的工作旨在了解MOV的形成，同时考虑到迷你暖池的影响和索马里急流的影响。 前者鼓励深对流，这反过来又可以促进涡的形成，在对流层中层，而后者可以产生一个涡，通过正压不稳定性在对流层低层的急流被发现。工作的目标是了解这两种机制如何联合收割机，以创建一个MOV。 这项工作涉及分析卫星任务的数据和再分析数据集，沿着用简单理想化模型和天气研究和预报模型生成的模拟。该项目还包括索马里急流的稳定性分析，同时考虑到其纬向切变和时间变化。鉴于MOV与季风爆发的联系及其产生强大登陆台风的趋势，这项工作具有社会和科学意义。该项目还向两名研究生和两名本科生提供支助和培训。 此外，PI还担任高中生的导师，并为北卡罗来纳州科学与数学学院的夏季研究计划做出贡献。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Two events over the Arabian Sea are clear precursors to the Indian summer monsoon: the formation of a "mini warm pool" of heightened sea surface temperatures (SSTs), and the extension of the low-level Somali jet across the Sea from the East African coast to the west coast of India. The jet brings moisture evaporated from the warm Arabian SSTs to coastal India triggering the monsoon, and in many years monsoon onset is accompanied by a cyclonic vortex known as the Monsoon Onset Vortex (MOV). The MOV is of interest not only for its association with monsoon onset but also because it can evolve into a typhoon and cause extensive damage on landfall.Work under this award seeks to understand the formation of the MOV, taking into account the influence of the mini warm pool and the influence of the Somali jet. The former encourages deep convection which in turn can promote vortex formation at mid-tropospheric levels, while the latter can generate a vortex through barotropic instability at the lower-tropospheric level where the jet is found. The goal of the work is to understand how these two mechanisms combine to create an MOV. The work involves analysis of data from satellite missions and reanalysis datasets along with simulations generated with both simple idealized models and the Weather Research and Forecasting (WRF) model. The project also includes a stability analysis of the Somali jet, taking into account both its latitudinal shear and its time variation.The work is of societal as well as scientific interest given the connection of the MOV with monsoon onset and its tendency to generate powerful landfalling typhoons. The project also provides support and training to two graduate students and two undergraduates. In addition, the PI serves as a mentor to high school students and contributes to the summer research program of the NC School of Science and Math.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.