Reply on RC1

Published: June 7, 2024

Abstract. We review how the international modelling community, encompassing Integrated Assessment models, global and regional Earth system climate impact have worked together over past few decades, to advance understanding of change its impacts on society environment, support policy. then recommend a number priority research areas for coming ~6 years (i.e. until ~2030), timescale that matches newly starting activities encompasses IPCC 7th Report (AR7) 2nd UNFCCC Global Stocktake. Progress in these will significantly our increase quality utility science emphasize need continued improvement of, ability simulate, coupled change. There is an urgent investigate plausible pathways emission scenarios realize Paris Climate Targets, including overshoot 1.5 °C 2 targets, before later returning them. System models (ESMs) be capable thoroughly assessing such warming overshoots, particular, efficacy negative CO₂ actions reducing atmospheric driving cooling. An improved assessment long-term consequences stabilizing at or above pre-industrial temperatures also required. ESMs run CO₂-emission mode, more fully represent - carbon cycle feedbacks. Regional downscaling should use forcing data from simulations, so projections are as realistic possible. accurate simulation observed record remains key requirement does metrics, Effective Sensitivity. For adaptation, guidance potential changes extremes modes variability develop in, demand. Such improvements most likely realized through combination increased model resolution parameterizations. propose deeper collaboration across efforts targeting process realism coupling, enhanced resolution, parameterization improvement, data-driven Machine Learning methods. With respect sampling future uncertainty, between approaches large ensembles those focussed statistical emulation attention paid High Impact Low Likelihood (HILL) outcomes. In risk exceeding critical tipping points during overshoot. comprehensive change, arising directly specific mitigation actions, it important detailed, disaggregated information Models (IAMs) used generate available models. Conversely, methods developed incorporate societal responses into scenario development. Finally, new data, scientific advances, proposed this article not possible without development maintenance robust, globally connected infrastructure ecosystem. This must easily accessible useable all communities world, allowing community engaged developing delivering knowledge

Language: Английский

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The Averaged Hydrostatic Boussinesq Equations in Generalized Vertical Coordinates

Authorea (Authorea), Journal Year: 2024, Volume and Issue: unknown

Published: June 24, 2024

Due to their limited resolution, numerical ocean models need be interpreted as representing filtered or averaged equations. How interpret in terms of formally equations, however, is not always clear, particularly the case hybrid generalized vertical coordinate models. We derive hydrostatic Boussinesq equations coordinates for an arbitrary thickness weighted-average. then consider various special cases and discuss extent which are consistent with existing model formulations. As previously discussed, momentum depth-coordinate best Eulerian averages (i.e., taken at fixed depth), while tracer can either thickness-weighted isopycnal averages. Instead we find that no averaging fully formulations parameterizations semi-Lagrangian discretizations Perhaps most natural interpretation assume average follows model’s surfaces. However, generally coordinate-following averages, would require “coordinate-aware” account changing nature eddy changes. Alternatively, variables (thickness-weighted) independent being used discretization. Existing models, usually these interpretations. what changes needed achieve consistency.

Language: Английский

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A Stable Implementation of a Data‐Driven Scale‐Aware Mesoscale Parameterization

Journal of Advances in Modeling Earth Systems, Journal Year: 2024, Volume and Issue: 16(10)

Published: Oct. 1, 2024

Abstract Ocean mesoscale eddies are often poorly represented in climate models, and therefore, their effects on the large scale circulation must be parameterized. Traditional parameterizations, which represent bulk effect of unresolved eddies, can improved with new subgrid models learned directly from data. Zanna Bolton (2020), https://doi.org/10.1029/2020gl088376 (ZB20) applied an equation‐discovery algorithm to reveal interpretable expression parameterizing momentum fluxes by through components velocity‐gradient tensor. In this work, we implement ZB20 parameterization into primitive‐equation GFDL MOM6 ocean model test it two idealized configurations significantly different dynamical regimes topography. The original was found generate excessive numerical noise near grid scale. We propose filtering approaches avoid issues additionally enhance strength large‐scale energy backscatter. filtered parameterizations led climatological mean state distributions, compared current state‐of‐the‐art backscatter parameterizations. scale‐aware and, consequently, used a single value non‐dimensional scaling coefficient for range resolutions. successful application parameterize offers promising opportunity reduce long‐standing biases global simulations future studies.

Language: Английский

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The Averaged Hydrostatic Boussinesq Ocean Equations in Generalized Vertical Coordinates

Journal of Advances in Modeling Earth Systems, Journal Year: 2024, Volume and Issue: 16(12)

Published: Dec. 1, 2024

Abstract Due to their limited resolution, numerical ocean models need be interpreted as representing filtered or averaged equations. How interpret in terms of formally equations, however, is not always clear, particularly the case hybrid generalized vertical coordinate models, which limits our ability model results and develop parameterizations for unresolved eddy contributions. We here derive hydrostatic Boussinesq equations coordinates an arbitrary thickness‐weighted average. then consider various special cases discuss extent are consistent with existing formulations. As previously discussed, momentum depth‐coordinate best Eulerian averages (i.e., taken at fixed depth), while tracer can either isopycnal averages. Instead we find that no averaging fully formulations semi‐Lagrangian discretizations such MOM6. A coordinate‐following average would require “coordinate‐aware” account changing nature changes. Alternatively, variables (thickness‐weighted) averages, independent being used discretization. Existing these interpretations, which, respectively, a three‐dimensional divergence‐free advection form‐stress parameterization

Language: Английский

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Machine learning for online sea ice bias correction within global ice-ocean simulations

arXiv (Cornell University), Journal Year: 2023, Volume and Issue: unknown

Published: Jan. 1, 2023

In this study we perform online sea ice bias correction within a GFDL global ice-ocean model. For this, use convolutional neural network (CNN) which was developed in previous (Gregory et al., 2023) for the purpose of predicting concentration (SIC) data assimilation (DA) increments. An initial implementation CNN shows systematic improvements SIC biases relative to free-running model, however large summertime errors remain. We show that these residual can be significantly improved with augmentation approach, sequential and DA corrections are applied new simulation over training period. This then provides set refine weights network. propose machine-learned scheme could utilized generating conditions, also real-time seasonal-to-subseasonal forecasts.

Language: Английский

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