Nowcasting with Artificial Intelligence for African Rainfall: NAIAR

该项目旨在利用新的数字解决方案，利用卫星数据对热带风暴进行0至6小时的预报——即临近预报。这些方法将通过我们现有的在线平台和智能手机应用程序为非洲开发和推广，那里的人们迫切需要有关风暴危害的信息。通过这种方式，研究结果将在几分钟内用于向用户提供有关风暴危害的信息。该项目与NERC数字战略密切相关。热带风暴非常难以预测，在一个小时左右的时间尺度上变化非常迅速——爆炸性的。由于这个原因，预测自然是非常不确定的。通常，人们需要的关于风暴危险的最重要的信息是现在正在发生的事情，以及关于风暴在未来几个小时内可能如何移动和发展的一些信息。这个过程被称为“临近预报”，在美国，龙卷风的临近预报每年能挽救许多人的生命。大多数非洲国家缺乏气象雷达，这意味着几乎完全没有临近预报，但我们最近表明，卫星方法也可以提供有用的风暴临近预报。从2024年左右开始，新的第三代气象卫星（MTG）将以更高的频率和更精细的空间尺度提供更好的数据覆盖。在创造新的临近预报方法并将其传达给非洲各地的气象服务、组织和公众方面，这是一个巨大的创新机会。现有的卫星临近预报方法虽然具有一定的技巧，但也存在较大的不足。它们通过外推观察到的模式向前发展，但不受物理定律的约束，非物理预测通常会发生。风暴临近预报中最具挑战性的问题是预测未来新风暴的形成和随后的发展：目前还没有公认的方法来做到这一点，而且我们对形成物理学的大量知识还没有得到利用。生成这些临近预报大约需要30分钟，当它们的精度在一两个小时后下降时，它们的使用就会受到限制。我们的目标是创建有用的6小时即时预报。临近投射是一个明显的应用，新的数据科学方法，特别是机器学习（ML），有可能产生巨大的影响，一些团体已经开始提出切实可行的解决方案。我们需要基础研究来理解和改进这些数据驱动的解决方案的性能，以风暴的潜在物理和流体动力学为基础。例如，现有的方法可以使用ML来预测风暴的未来运动或增长，但结果可能会以一种与物理定律不相容的方式增长和扭曲形状。对于经验丰富的预测者来说，这些不切实际的预测是显而易见的，但这些数据的普通用户将容易受到不准确的临近预报的影响。当使用即时预报来预测洪水等灾害时，非物理的解决方案可能会导致错误的决策。在这个项目中，我们的目标是结合机器学习、理论流体动力学、业务预测和气象学，创造热带风暴临近预报的创新方法。我们将开发速度快、遵守物理定律的机器学习方法，比如天气预报模型。我们的解决方案将包括降雨概率的统计预测，以及预测实现的集合，并将创建一个自动评估系统。物理认识的最新进展和MTG提供的新数据将用于创建风暴开始及其随后演变的统计临近预报。我们将通过我们现有的网络和移动电话通信门户网站向非洲提供信息，并支持非洲的同事在当地利用这些方法。

This project aims to use new digital solutions to create 0 to 6 hour predictions - nowcasting - for tropical storms using satellite data. The methods will be developed and rolled-out for Africa, where people urgently need information about storm hazards, through our existing online platforms and smartphone apps. In this way the results of the research will be used to deliver information on storm hazards to users within minutes. The project very closely addresses the NERC Digital Strategy. Tropical storms are very unpredictable, changing very rapidly - explosively - over timescales of an hour or so. For this reason, predictions are naturally very uncertain. Very often, the most important information people need regarding a storm hazard is what is happening now, and some information about how the storm likely to move and develop in the next couple of hours. This process is called "nowcasting" and in the USA, nowcasting of tornados saves many lives every year. The lack of weather radars in most African countries means that nowcasting is almost completely absent, but we have recently shown that satellite methods can provide useful nowcasting of storms too. The new Meteosat Third Generation (MTG) satellite will provide even better data coverage, from about 2024, at higher frequency and finer spatial scale. There is a tremendous opportunity to innovate in the creation of new nowcasting methods and communicate them to weather services, organisations and the public across Africa.While existing satellite nowcasting methods have some skill, they also have major shortcomings. They work by extrapolating observed patterns forward in time, but are not constrained to obey the laws of physics, and unphysical predictions commonly occur. The most challenging problem in storm nowcasting is to predict the initiation and subsequent development of new storms in future: there is no accepted way to do this, and our considerable knowledge of the physics of initiation is not being exploited. It takes about 30 minutes to generate these nowcasts, and when their accuracy is degrading after an hour or two, their use becomes limited. We aim to create useful 6-hour nowcasts.Nowcasting is an obvious application where new data-science methods, in particular machine-learning (ML), have the potential to make a massive impact, and a number of groups have begun to propose practical solutions. We need fundamental research to understand and improve the performance of these data-driven solutions, on the basis of the underlying physics and fluid-dynamics of storms. For instance, existing methods can extrapolate an image of a storm forward in time using ML to predict its future movement or growth, but the result may grow and be distorted in shape in a way which is incompatible with the laws of physics. These unrealistic predictions are obvious to an experienced forecaster but ordinary users of the data will be vulnerable to the consequences of inaccurate nowcasts. When nowcasts are used to predict hazards such as floods, unphysical solutions could lead to bad decisions.In this project, we aim to combine machine-learning, theoretical fluid dynamics, operational prediction and meteorology, to create innovative approaches to nowcasting of tropical storms. We will develop ML methods which are fast, and which obey physical laws, like the weather prediction models. Our solutions will include statistical forecasts of rainfall probabilities, as well as ensembles of forecast realisations, and an automated evaluation system will be created. Recent advances in physical understanding and the new data offered by MTG, will be used to create statistical nowcasts of storm initiation and its subsequent evolution. We will apply these methods through our existing web-based and mobile-phone communication portals delivering information to Africa, and support colleagues in Africa to exploit the methods locally.