Climate‐change modelling at reduced floating‐point precision with stochastic rounding

Quarterly Journal of the Royal Meteorological Society Wiley 149:752 (2023) 843-855

Authors:

Tom Kimpson, E Adam Paxton, Matthew Chantry, Tim Palmer

Sub-seasonal to decadal predictions in support of climate services

Climate Services Elsevier 30 (2023) 100397

Authors:

Marisol Osman, Daniela IV Domeisen, Andrew W Robertson, Antje Weisheimer

A statistical perspective on the signal–to–noise paradox

Quarterly Journal of the Royal Meteorological Society Wiley 149:752 (2023) 911-923

Authors:

Jochen Broecker, Andrew Charlton-Perez, Antje Weisheimer

Abstract:

An anomalous signal-to-noise ratio (also called the signal-to-noise paradox) present in climate models has been widely reported, affecting predictions and projections from seasonal to centennial timescales and encompassing prediction skill from internal processes and external climate forcing. An anomalous signal-to-noise ratio describes a situation where the mean of a forecast ensemble correlates better with the corresponding verification than with its individual ensemble members. This situation has severe implications for climate science, meaning that large ensembles might be required to extract prediction signals. Although a number of possible physical mechanisms for this paradox have been proposed, none has been universally accepted. From a statistical point of view, an anomalous signal-to-noise ratio indicates that forecast ensemble members are not statistically interchangeable with the verification, and an apparent paradox arises only if such an interchangeability is assumed. It will be demonstrated in this study that an anomalous signal-to-noise ratio is a consequence of the relative magnitudes of the variance of the observations, the ensemble mean, and the error of the ensemble mean. By analysing the geometric triangle formed by these three quantities, and given that for typical seasonal forecasting systems both the correlation and the forecast signal are relatively small, it is concluded that an anomalous signal-to-noise ratio should, in fact, be expected in such circumstances.

Scaling up gas and electric cooking in low- and middle-income countries: climate threat or mitigation strategy with co-benefits?

Environmental Research Letters IOP Publishing 18:3 (2023) 034010

Authors:

Emily Floess, Andrew Grieshop, Elisa Puzzolo, Dan Pope, Nicholas Leach, Christopher J Smith, Annelise Gill-Wiehl, Katherine Landesman, Rob Bailis

Challenges with interpreting the impact of Atlantic Multidecadal Variability using SST-restoring experiments

npj Climate and Atmospheric Science Springer Nature 6:1 (2023) 14

Authors:

Christopher HH O'Reilly, Matthew Patterson, Jon Robson, Paul Arthur Monerie, Daniel Hodson, Yohan Ruprich-Robert

Abstract:

Climate model simulations that restore SSTs in the North Atlantic have been used to explore the climate impacts of Atlantic Multidecadal Variability (AMV). However, despite simulations and observations exhibiting similar North Atlantic SST anomalies, experiments with active SST-restoring in the Tropical North Atlantic exhibit strong positive surface heat-fluxes out of the ocean with warm SST anomalies, which is not replicated in other simulations or observations. The upward surface heat-fluxes that are systematically driven by the active SST-restoring in the Tropical North Atlantic are found to be crucial for generating a strong local precipitation response and the associated remote impact on the Pacific Walker circulation; these are both absent in other simulations. The results of this study strongly suggest that experiments employing SST-restoring (or prescribed SSTs) in the Tropical North Atlantic exaggerate the influence of the Atlantic on patterns of global climate anomalies and its role in recent multidecadal SST trends.