Philippe Lucas-Picher, Daniel Argüeso, Erwan Brisson, Yves Tramblay, Peter Berg, Aude Lemonsu, Sven Kotlarski, Cécile Caillaud
Wiley Interdisciplinary Reviews: Climate Change
Work Package 3
Link: https://doi.org/10.1002/wcc.731
Highlights
High-resolution climate models, particularly those capable of simulating deep atmospheric convection explicitly, are better able to represent extreme climatic events and small-scale processes than their lower-resolution counterparts, at the cost of being computationally expensive to run. This paper presents a review of the latest science around these Convection-Permitting Regional Climate Models (CPRCMs), including demonstrations of their advancements over lower-resolution climate models and where they can be of most use, their remaining drawbacks and how they can be addressed, and specific use cases. Improving our predictions of future climate change using these models can help communities and policymakers prepare for the effects of future climate change and reduce its impact.
Background
Convection-Permitting Regional Climate Models (CPRCMs) are high-resolution models of the Earth’s climate system. They are capable of simulating deep atmospheric convection, a key process in many extreme weather events, rather than using parameterizations, which are based on simple assumptions. The large supercomputing resources they require have limited their use in climate modelling. Improved computer power, however, has now made their use in climate projections more viable, and this new field has advanced greatly in the past 10 years. This review looks at current research and the latest findings on CPRCMs, including the improvements they can bring to our projections of future climate, before looking at the next steps in the field and the further advances that can be made to exploit the full potential of CPRCMs.
Current research
This review highlights some of the advantages that CPRCMs have over lower-resolution models and the advances they have brought in modelling certain climate features. Various studies looking at different parts of the world have demonstrated that CPRCMs are better able to simulate the daily cycle of rainfall due to their explicit simulation of deep atmospheric convection and the factors that affect it. Rainfall frequency, intensity and duration are also improved, while a major benefit of CPRCMs is their ability to simulate extreme climatic events more accurately. This provides significant benefits when it comes to planning for such events and minimising their impact. Surface temperatures have also been shown to be better simulated in CPRCMs over many different areas. Cyclones and monsoons are better represented with CPRCMs, helping mitigate their impacts, while the high resolution of CPRCM simulations is particularly valuable for characterising climate change in urban areas. Recently, researchers have been able to run ensembles of CPRCMs over specific regions allowing them to better estimate the uncertainties in climate projections. The computational cost of the models had previously prevented this type of analysis.
Next steps
CPRCMs have brought important insights on key aspects of climate change, particularly local and extreme impacts. Some future work on these models will focus on addressing some of their remaining drawbacks. CPRCMs still require significant computational resources and produce very large outputs. This limits the size of the simulation domain, as well as the size of the simulation ensembles. High-resolution observations of the climate are also lacking, limiting our ability to fully evaluate CPRCM simulations. Many of these issues are being addressed through current research projects and advancements in technology. Climate services will have to adapt to be able to process the very large amounts of data that CPRCMs produce. This is a key part of producing valuable, user-relevant information from these advanced climate models.
Policy relevance
This review highlights the current benefits of CPRCMs and the areas in which further research can bring additional improvements. These models can greatly improve our simulations of extreme weather and small-scale changes in the climate, such as in cities. This helps inform effective policies to limit the impact of future climate change, mitigating the risk it poses.
Abstract
Approximately 10 years ago, convection-permitting regional climate models (CPRCMs) emerged as a promising computationally affordable tool to produce fine resolution (1–4 km) decadal-long climate simulations with explicitly resolved deep convection. This explicit representation is expected to reduce climate projection uncertainty related to deep convection parameterizations found in most climate models. A recent surge in CPRCM decadal simulations over larger domains, sometimes covering continents, has led to important insights into CPRCM advantages and limitations. Furthermore, new observational gridded datasets with fine spatial and temporal (~1 km; ~1 h) resolutions have leveraged additional knowledge through evaluations of the added value of CPRCMs. With an improved coordination in the frame of ongoing international initiatives, the production of ensembles of CPRCM simulations is expected to provide more robust climate projections and a better identification of their associated uncertainties. This review paper presents an overview of the methodology to produce CPRCM simulations and the latest research on the related added value in current and future climates. Impact studies that are already taking advantage of these new CPRCM simulations are highlighted. This review paper ends by proposing next steps that could be accomplished to continue exploiting the full potential of CPRCMs.
Funded by the European Union under Horizon 2020.