Stochastic Parameterisations and Model Uncertainty in the Lorenz '96 system
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences Royal Society 371 (2013) 20110479
Should weather and climate prediction models be deterministic or stochastic?
Weather Wiley 68:10 (2013) 264-264
Aerodynamic Stability and the Growth of Triangular Snow Crystals
The Microscope McCrone Research Institute 4:57 (2009) 157-163
Abstract:
We describe laboratory-grown snow crystals that exhibit a triangular, plate-like morphology, and we show that the occurrence of these crystals is much more frequent than one would expect from random growth perturbations of the more-typical hexagonal forms. We then describe an aerodynamic model that explains the formation of these crystals. A single growth perturbation on one facet of a hexagonal plate leads to air flow around the crystal that promotes the growth of alternating facets. Aerodynamic effects thus produce a weak growth instability that can cause hexagonal plates to develop into triangular plates. This mechanism solves a very old puzzle, as observers have been documenting the unexplained appearance of triangular snow crystals in nature for nearly two centuries.A machine learning-based approach to quantify ENSO sources of predictability
Geophysical Research Letters American Geophysical Union
Abstract:
A machine learning method is used to identify sources of long-term ENSO predictability in the ocean (sea surface temperature (SST) and heat content) and the atmosphere (near-surface zonal wind (U10)). Tropical SST represents the primary source of predictability skill. While U10 does not increase the skill when associated with SST, our analysis suggests U10 alone can predictive skill comparable to that of SST between 11-21 months in advance, from late fall up to late spring. The long-lead signal originates from coupled wind-SST interactions across the Indian Ocean (IO) and propagates across the Pacific via an atmospheric bridge mechanism. A linear correlation analysis supports this mechanism, suggesting a precursor link between anomalies in SST in the western and wind in the eastern IO. Our results have important implications for ENSO predictions beyond one year ahead and identify the key role of U10 over the IO.Climate SPHINX: evaluating the impact of resolution and stochastic physics parameterisations in climate simulations
Geoscientific Model Development European Geosciences Union