Speaker – Greg Hakim, Professor, University of Washington. This semester’s special Braham Seminar.

Seminar Title – Using Machine-Learning Weather Models to Study Predictability and Extreme Events

Abstract – Recently developed machine-learning (ML) weather models have been widely recognized for revolutionizing weather prediction, producing forecasts more skillful than traditional models at a fraction of the computational cost. Here I will argue that the next phase of the revolution involves the adjoints of these models, applied to a wide range of problems, including novel exploration of dynamical process in weather and climate variability. Adjoints, which derive from gradient operations on a model, are useful for measuring the sensitivity of model outputs to inputs and parameters. The ubiquitous availability of adjoints for ML models makes these tools easily accessible and available for a wide range of applications. Specific examples I will discuss include shadowing trajectories for testing the limit of predictability and exploring gray swan extreme events.

About the Speaker – Greg Hakim is well known as a dynamic and synoptic meteorologist, and is a co-author on the most recent edition of the classic textbook “An Introduction to Dynamic Meteorology” with Jim Holton.  His most recent contributions have focused on novel uses of AI/ML for weather and climate prediction, so we anticipate a presentation of very broad appeal and applicability.

The annual Braham seminar is named in honor of Dr. Roscoe Braham, a visiting professor at North Carolina State University and a pioneering meteorologist, educator, and expert in cloud precipitation physics. He earned a bachelor’s degree in geology in 1942 from Ohio University. Braham completed his master’s and doctoral degrees at the University of Chicago, joined the University of Chicago staff in 1952 as a research meteorologist and retired in 1991 after 37 years, 26 of them as a full professor. Braham published more than eighty scientific reports, books and monographs during his academic career. Braham joined the American Meteorological Society in 1945 and served as its president in 1988. He is credited for the discovery of the cell organization of thunderstorms, as well as the coalescence-freezing mechanism of precipitation formation in natural clouds (x).