To join this seminar virtually: Please request Zoom connection details from ea [at] stat.ubc.ca
Abstract: Earth System Models (ESMs) are state-of-the-art mathematical formulations used to describe the Earth’s climate system. Supported by supercomputing resources, ESMs can generate large-ensemble, high-resolution global climate simulations, which supplement real-world observations and enhance our understanding of climate changes and their associated variabilities. However, the substantial computational and storage demands of these simulations often limit their broader utility. We propose an efficient statistical emulator—referred to as a stochastic generator (SG)—to address these challenges. By applying the spherical harmonic transformation (SHT), the SG converts climate simulations into a lower-dimensional spectral domain, significantly reducing computational and storage requirements. As a practical complement to ESMs, the SG can rapidly generate multiple emulations of climate simulations. We demonstrate this approach by developing an SG for surface temperature simulations from the newly published CESM2-LENS2 data. To capture non-stationary spatial dependencies, our model incorporates axial symmetry and applies distinct ranks for land and ocean regions. To handle non-Gaussianity in high-temporal-resolution data, we use a modified Tukey g-and-h transformation. The SG successfully emulates CESM2-LENS2 surface temperature simulations across multiple scales, marking the first attempt at reproducing daily data. With the support of supercomputers, we further validate the SG's scalability by emulating ultra-high-resolution climate simulations—an achievement that contributed to winning the prestigious 2024 Gordon Bell Prize for Climate Modelling. Finally, we extend the SG's capabilities to near real-time regional climate simulations by leveraging Slepian concentration on the sphere and an online updating technique. These developments offer a promising complementary pathway for efficient climate modeling and analysis, overcoming critical computational and storage barriers.
***
Please note that this seminar will now be held virtually only, and will not take place in person.