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Exploring stochastic and multi-scale modeling approaches for a seamless prediction system

Banff International Research Station for Mathematical Innovation and Discovery

Stochastic schemes to represent model uncertainty in the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble prediction system has helped improve its probabilistic forecast skill over the past decade by both improving its reliability and reducing the ensemble mean error. The largest uncertainties in the model arise from the model physics parameterizations. In the tropics, the parameterization of moist convection presents a major challenge for the accurate prediction of weather and climate. Super-parameterisation is a promising recent alternative strategy for including the effects of moist convection through explicit turbulent fluxes calculated from a cloud-resolving model (CRM) embedded within a global climate model (GCM). These two approaches (stochastic and super-parameterization) in convection parameterization have emerged as new paths forward and complement the conventional approaches rather than replace them. We study the impact of these two approaches and a combination of the two on forecasts from weather to sub-seasonal and climate timescales. Results from the evaluation of model forecast skill and fidelity in the Tropics and for organized convective systems such as the MJO will be presented. We show that the combination of the two approaches helps improve the reliability of forecasts of certain tropical phenomena, especially in regions that are affected by deep convective systems. This has implications for improving conventional convection parameterization using hybrid approaches for probabilistic earth system forecasting as we await the exascale computing systems of the future to resolve convective processes in climate models.

Mathematics; Partial differential equations; Dynamical systems and ergodic theory

video/mp4

Author affiliation: University of California, San Diego

2018-05-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/66036

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/