Severe weather over Southeast Asia

东南亚的海洋大陆（主要是马来西亚、印度尼西亚和巴布亚新几内亚）在全球天气和气候系统中起着关键作用。其复杂的岛屿地理位置和地球上最温暖的海洋之间的位置导致强烈的对流天气系统，产生强烈的降雨，导致洪水和山体滑坡等灾害。反过来，这些天气系统释放的大量潜热迫使全球大气响应，从而影响整个地球的天气和气候。昼夜循环是海洋大陆有组织对流的基本组成部分。概念模式表明，对流是在下午晚些时候开始内陆的海岸线，由于上坡山风和海风收敛。在夜间，下坡山风、陆地微风和重力波的组合导致对流向离岸传播，变得更加有组织，产生了许多岛屿共同的独特的昼夜循环。由于在如此复杂的地理环境中模拟热带大气和海洋的困难，我们对这个多尺度系统中的过程的理解存在重大的知识空白，缺乏合适的现场观测来评估模型。这种缺乏了解是该地区天气预报和气候预测的一个重大限制，考虑到大规模的印记，对热带和热带以外的其他地区也是如此。国际倡议“海洋大陆年”（YMC）目前正在进行中，包括英国通过为期5年的NERC大型赠款“TerraMaris”的贡献，其中包括2022年的空中和地面实地考察（取决于新冠肺炎疫情）和广泛的建模。这个博士项目为学生提供了一个独特的机会，参与国际项目，并利用卫星产品，广泛和独特的现场观测已经通过YMC和TerraMaris建模。如果COVID-19允许，将有机会参加印度尼西亚的研究飞机飞行或地面实地考察。具体而言，该项目将：利用YMC提供的地面雷达观测，评价海洋大陆分区域全球定位系统多卫星综合反演的降雨量反演。（特别是该地区的Himawari-8），地面雷达和现场观测，以研究导致强对流风暴形成和传播的大气过程（图一）。过程包括海陆风、风暴外流、云的形成和重力波。研究背景状态的低频调制（例如风的变化，稳定性和湿度通过年周期和马登-朱利安振荡）影响海洋大陆对流的发生和传播。评估不同复杂性的数值天气模式如何代表严重风暴的形成，并使用这些模式研究关键气象局CASE奖将使学生获得一套最先进的模型产品和计算设施，以及工作人员在遥感和现场观测、建模和理解大气过程（如对流）方面的专业知识。学生将在利兹大学注册。

The Maritime Continent in Southeast Asia (predominately Malaysia, Indonesia and Papua New Guinea) plays a key role in the global weather and climate system. Its complex island geography and position among the warmest oceans on Earth lead to severe convective weather systems that produce intense rainfall, leading to disasters such as flooding and landslides. In turn, the large amounts of latent heat released from these weather systems force a global atmospheric response, which affects weather and climate across the Earth.The diurnal cycle is the fundamental building block of organised convection over the Maritime Continent. Conceptual models suggest that convection is initiated inland of the coastlines during the late afternoon due to upslope mountain winds and sea breeze convergence. During the night, a combination of downslope mountain winds, the land breeze and gravity waves causes the convection to propagate offshore and become more organised, producing a distinct diurnal cycle that is common to many of the islands.There are major knowledge gaps in our understanding of the processes within this multi-scale system due to difficulties modelling the tropical atmosphere and ocean over such complex geography, and a dearth of suitable in-situ observations against which to evaluate models. This lack of understanding is a significant limitation to weather forecasting and climate projections in the region as well as, given the large-scale imprint, on the rest of the tropics and the extra-tropics.The international initiative "Years of the Maritime Continent" (YMC) is currently underway, including the UK contribution through a 5-year NERC large grant "TerraMaris", which includes air- and ground-based fieldwork in 2022 (Covid-19 dependent) and extensive modelling. This PhD project provides a unique opportunity for a student to be involved in the international project and make use of satellite products, extensive and unique in-situ observations already made through YMC, and TerraMaris modelling. There will be an opportunity to take part in research aircraft flights or ground-based fieldwork in Indonesia if Covid-19 allows.Specifically, the project will:Evaluate rainfall retrievals from the Integrated Multi-satellitE Retrievals for GPM (IMERG) over sub-regions of the Maritime Continent using ground-based radar observations available through YMC.Use satellite rainfall retrievals and IR brightness temperature data from geostationary satellites (specifically Himawari-8 in this region), ground-based radar and in-situ observations to study the atmospheric processes that lead to the initiation and propagation of severe convective storms (Fig. 1). Processes include the land-sea breeze, storm outflows, cloud formation and gravity waves.Investigate how low-frequency modulations of the background state (e.g. variability in wind, stability and humidity through the annual cycle and Madden-Julian Oscillation) impact the initiation and propagation of Maritime Continent convection.Evaluate how numerical weather models of varying complexity represent severe storm formation and use these models to study key processes beyond the limitations of the observations.Provide research that will ultimately lead to improved weather forecast models and weather forecasting practises.The Met Office CASE award will allow the student access to a suite of state-of-the-art model products and computing facilities as well as staff expertise in remote sensing and in-situ observations, modelling and understanding of atmospheric processes such as convection. The student will be based and registered at the University of Leeds.