Intercomparison of global storm resolving (coupled) climate models

2020 ◽  
Author(s):  
Daniel Klocke ◽  
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Winter Period ◽  
Boreal Winter ◽  
Climate Modelling ◽  
Coupled Models ◽  
Phase 0 ◽  
First Results ◽  
Intercomparison Project ◽  
Convection Patterns

<p>The DYAMOND (DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains) project is an intercomparison project for global storm resolving models with horizontal resolutions < 5km. In Phase 0, nine models participated in simulating a 40 day period from August 2016 on. Now, Phase 0 of DYAMOND will be complemented by a boreal winter period and atmospher-ocean coupled models with the goal to: (i) compare the representation of the Madden-Julian-Oscillation in this class of models; (ii) investigate the effect of the atmosphere-ocean coupling at storm and ocean-eddy resolving scales on convection and the general circulation; and (III) link to the EUREC4A campaign, which targets meso-scale convection patterns and the coupling to the upper ocean processes. First results from the intercomparison of this new class of climate models will be presented, giving an outlook to the future of climate modelling.</p>

scholarly journals Considerable Model–Data Mismatch in Temperature over China during the Mid-Holocene: Results of PMIP Simulations

2012 ◽  
Vol 25 (12) ◽  
pp. 4135-4153 ◽  
Author(s):  
Dabang Jiang ◽  
Xianmei Lang ◽  
Zhiping Tian ◽  
Tao Wang
Keyword(s):  
Climate Models ◽  
Boreal Winter ◽  
Seasonal Temperature ◽  
Model Data ◽  
National Scale ◽  
Coupled Models ◽  
Winter Climate ◽  
Climate Conditions ◽  
Intercomparison Project ◽  
Better Than

Abstract Using the experiments undertaken by 36 climate models participating in the Paleoclimate Modeling Intercomparison Project (PMIP), this study examines annual and seasonal surface temperatures over China during the mid-Holocene. Compared to the present or preindustrial climate, 35 out of the 36 PMIP models reproduced colder-than-baseline annual temperature, with an average cooling of 0.4 K, during that period. Seasonal temperature change followed closely the change in incoming solar radiation at the top of the atmosphere over China during the mid-Holocene. Temperature was reduced (elevated) in boreal winter and spring (summer) in all of the PMIP models, with an average of 1.4 K (1.0 K) at the national scale. Colder (warmer)-than-baseline temperatures were derived from 14 of the 16 atmosphere-only (18 of the 20 coupled) models during the mid-Holocene boreal autumn. Interactive ocean was found to lead to a warming effect on annual (0.3 K), boreal winter (0.5 K), and boreal autumn (0.7 K) temperatures, with reference to the atmosphere-only models. Interactive vegetation had little impact in terms of six pairs of coupled models with and without vegetation effects. The above results are in stark contrast to warmer-than-present annual and winter climate conditions as derived from multiproxy data for the mid-Holocene. Coupled models generally perform better than atmosphere-only models.

Efficient estimation and ensemble generation in climate modelling

2007 ◽  
Vol 365 (1857) ◽  
pp. 2077-2088 ◽  
Author(s):  
J.D Annan ◽  
J.C Hargreaves
Keyword(s):  
Monte Carlo ◽  
Particle Filtering ◽  
General Circulation ◽  
Climate Models ◽  
General Circulation Models ◽  
Monte Carlo Sampling ◽  
Efficient Estimation ◽  
Future Research ◽  
Great Promise ◽  
Climate Modelling

In this paper, we review progress towards efficiently estimating parameters in climate models. Since the general problem is inherently intractable, a range of approximations and heuristic methods have been proposed. Simple Monte Carlo sampling methods, although easy to implement and very flexible, are rather inefficient, making implementation possible only in the very simplest models. More sophisticated methods based on random walks and gradient-descent methods can provide more efficient solutions, but it is often unclear how to extract probabilistic information from such methods and the computational costs are still generally too high for their application to state-of-the-art general circulation models (GCMs). The ensemble Kalman filter is an efficient Monte Carlo approximation which is optimal for linear problems, but we show here how its accuracy can degrade in nonlinear applications. Methods based on particle filtering may provide a solution to this problem but have yet to be studied in any detail in the realm of climate models. Statistical emulators show great promise for future research and their computational speed would eliminate much of the need for efficient sampling techniques. However, emulation of a full GCM has yet to be achieved and the construction of such represents a substantial computational task in itself.

scholarly journals The Cloud Feedback Model Intercomparison Project (CFMIP) Diagnostic Codes Catalogue – metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models

2017 ◽  
Author(s):  
Yoko Tsushima ◽  
Florent Brient ◽  
Stephen A. Klein ◽  
Dimitra Konsta ◽  
Christine Nam ◽  
...  
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Evaluation Studies ◽  
Circulation Model ◽  
Community Analysis ◽  
Model Intercomparison ◽  
Cloud Feedbacks ◽  
Diagnostic Codes ◽  
Feedback Model ◽  
Intercomparison Project

Abstract. The CFMIP Diagnostic Codes Catalogue assembles cloud metrics, diagnostics and methodologies, together with programs to diagnose them from General Circulation Model (GCM) outputs written by various members of the CFMIP community. This aims to facilitate use of the diagnostics by the wider community studying climate and climate change. This paper describes the diagnostics and metrics which are currently in the catalogue, together with examples of their application to model evaluation studies and a summary of some of the insights these diagnostics have provided on the main shortcomings in current GCMs. Analysis of outputs from CFMIP and CMIP6 experiments will also be facilitated by the sharing of diagnostic codes via this catalogue. Any code which implements diagnostics relevant to analysing clouds – including cloud-circulation interactions and the contribution of clouds to estimates of climate sensitivity in models – and which is documented in peer-reviewed studies can be included in the catalogue. We very much welcome additional contributions to further support community analysis of CMIP6 outputs.

scholarly journals ENSO Seasonal Synchronization Theory

2014 ◽  
Vol 27 (14) ◽  
pp. 5285-5310 ◽  
Author(s):  
Karl Stein ◽  
Axel Timmermann ◽  
Niklas Schneider ◽  
Fei-Fei Jin ◽  
Malte F. Stuecker
Keyword(s):  
Annual Cycle ◽  
General Circulation ◽  
Phase Synchronization ◽  
Southern Oscillation ◽  
General Circulation Models ◽  
Boreal Winter ◽  
Nonlinear Frequency ◽  
Coupled Models ◽  
Frequency Locking ◽  
Enso Events

Abstract One of the key characteristics of El Niño–Southern Oscillation (ENSO) is its synchronization to the annual cycle, which manifests in the tendency of ENSO events to peak during boreal winter. Current theory offers two possible mechanisms to account the for ENSO synchronization: frequency locking of ENSO to periodic forcing by the annual cycle, or the effect of the seasonally varying background state of the equatorial Pacific on ENSO’s coupled stability. Using a parametric recharge oscillator (PRO) model of ENSO, the authors test which of these scenarios provides a better explanation of the observed ENSO synchronization. Analytical solutions of the PRO model show that the annual modulation of the growth rate parameter results directly in ENSO’s seasonal variance, amplitude modulation, and 2:1 phase synchronization to the annual cycle. The solutions are shown to be applicable to the long-term behavior of the damped model excited by stochastic noise, which produces synchronization characteristics that agree with the observations and can account for the variety of ENSO synchronization behavior in state-of-the-art coupled general circulation models. The model also predicts spectral peaks at “combination tones” between ENSO and the annual cycle that exist in the observations and many coupled models. In contrast, the nonlinear frequency entrainment scenario predicts the existence of a spectral peak at the biennial frequency corresponding to the observed 2:1 phase synchronization. Such a peak does not exist in the observed ENSO spectrum. Hence, it can be concluded that the seasonal modulation of the coupled stability is responsible for the synchronization of ENSO events to the annual cycle.

scholarly journals Extreme Events Representation in CMCC-CM2 High and Very-High Resolution General Circulation Models

2021 ◽  
Author(s):  
Enrico Scoccimarro ◽  
Daniele Peano ◽  
Silvio Gualdi ◽  
Alessio Bellucci ◽  
Tomas Lovato ◽  
...  
Keyword(s):  
High Resolution ◽  
Extreme Events ◽  
General Circulation ◽  
Climate Models ◽  
General Circulation Models ◽  
Horizontal Resolution ◽  
Historical Period ◽  
Climate Modelling ◽  
Temperature And Precipitation ◽  
Very High

Abstract. The recent advancements in climate modelling partially build on the improvement of horizontal resolution in different components of the simulating system. A higher resolution is expected to provide a better representation of the climate variability, and in this work we are particularly interested in the potential improvements in representing extreme events of high temperature and precipitation. The two versions of the CMCC-CM2 model used here, adopt the highest horizontal resolutions available within the last family of the global coupled climate models de¬veloped at CMCC to participate in the CMIP6 effort. The main aim of this study is to document the ability of the CMCC-CM2 models in representing the spatial distribution of extreme events of temperature and precipitation, under the historical period, comparing model results to observations (ERA5 Reanalysis and CHIRPS observations). For a more detailed evaluation we investigate both 6 hourly and daily time series for the definition of the extreme conditions. In terms of mean climate, the two models are able to realistically reproduce the main patterns of temperature and precipitation. The very-high resolution version (¼ degree horizontal resolution) of the atmospheric model provides better results than the high resolution one (one degree), not only in terms of means but also in terms of extreme events of temperature defined at daily and 6-hourly frequency. This is also the case of average precipitation. On the other hand the extreme precipitation is not improved by the adoption of a higher horizontal resolution.

Navigating the challenges of explicitly including ocean-ice shelf interactions in a global ocean model using an adapted ISOMIP+ configuration as a fit-for-purpose tool

2021 ◽  
Author(s):  
Katherine Hutchinson ◽  
Julie Deshayes ◽  
Pierre Mathiot
Keyword(s):  
Critical Role ◽  
Ocean Model ◽  
Global Ocean ◽  
Climate Modelling ◽  
Model Intercomparison ◽  
Ice Shelf ◽  
Coupled Models ◽  
Ocean Climate ◽  
Dense Water ◽  
Intercomparison Project

<p>Currently, none of the global 1° ocean-climate coupled models used for the Coupled Model Intercomparison Project (CMIP) explicitly simulate sub-ice shelf cavity circulation. This circulation plays a critical role in global ocean overturning as it transforms salty water formed at the surface in Antarctica into the parent waters of Antarctic Bottom Water (AABW). A challenge that the ocean-climate modelling community faces is the inclusion of these ocean-ice shelf interactions in global ocean 1° resolution models, so as to explicitly simulate dense water production and export. Choices regarding various numerical schemes and parameterizations need to be made, but in testing sensitivity to these choices and feedback effects of biases, large super-computing costs associated with running a global configuration are incurred. To address this we present an adapted configuration of the Ice Shelf-Ocean Model Intercomparison Project (ISOMIP), named ISOMIP+K, as the default idealised ISOMIP+ setup is not appropriate for modelling the deep, cold Antarctic cavities responsible for forming the dense parent waters of AABW. ISOMIP+K is currently adapted for the NEMO ocean model, motivated by the fact that this model is used for 6 of the climate groups participating in CMIP. We present results from ISOMIP+K configurations for Filchner-Ronne, Larsen-C and Ross ice shelves, which are important for dense water formation and large enough to be resolved, albeit coarsely, in a global 1° Earth System Model. This adapted ISOMIP+K test case, which is now far from idealized, is used to test the effect of initial conditions, the choice of values for lateral diffusion of momentum, mixing, drag coefficients and bathymetry on key indicators describing melt, sub-ice shelf circulation and dense water export. As opposed to regional high resolution Southern Ocean configurations, the ISOMIP+K configurations are designed so that the lessons learnt are directly transferable to a global ocean configuration where each choice made is backed-up by extensive, yet affordable, testing.</p>

ENSO teleconnections in an ensemble of CORDEX-CORE regional simulations

2021 ◽  
Author(s):  
Abraham Torres-Alavez ◽  
Fred Kucharski ◽  
Erika Coppola ◽  
Lorena Castro
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Permutation Test ◽  
Southern Oscillation ◽  
Statistical Significance ◽  
Regional Climate ◽  
General Circulation Models ◽  
Boreal Winter ◽  
Climate Change Research ◽  
Teleconnection Patterns

<p>Using high-spatial-resolution regional simulations from the global program, Coordinated Regional Climate Downscaling Experiment-Coordinated Output for Regional Evaluations (CORDEX-CORE), we examine the capability of regional climate models (RCMs) to represent the El Niño–Southern Oscillation (ENSO) precipitation and surface air temperature teleconnections during boreal winter (December-February). This study uses CORDEX-CORE simulations for the period 1975-2004 with two RCMs, the RegCM4 and REMO, driven by three General Circulation Models (GCMs) from phase 5 of the Coupled Model Inter-comparison Project (CMIP5). The RCM simulations were run at a 25-km grid spacing over Africa, Central and North America, South Asia and South America.</p><p>The teleconnection patterns are calculated in the reanalysis data (observations), and these results are compared to those of the ensemble and individual simulations of both the GCM and RCM. Linear regression is used to calculate the teleconnection patterns and a permutation test is applied to calculate the statistical significance of the regression coefficients. Results show that overall, the ENSO signal from the GCMs is preserved in the ensemble and the individual RCM simulations over most of the regions analyzed. These reproduced most of the observed regional responses to ENSO forcing and showing teleconnection signals statistically significant at the 95% level. Furthermore, in some cases, the ensemble and individual simulations of RCMs improve the spatial pattern and the amplitude of the ENSO precipitation response of the GCMs, particularly over southern Africa, the Arabian-Asian region, and the region composed of Mexico and the southern United States. These results show the potential value of the GCM-RCM downscaling systems not only in the context of climate change research but also for seasonal to annual prediction.</p>

scholarly journals The Cloud Feedback Model Intercomparison Project (CFMIP) Diagnostic Codes Catalogue – metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models

2017 ◽  
Vol 10 (11) ◽  
pp. 4285-4305 ◽  
Author(s):  
Yoko Tsushima ◽  
Florent Brient ◽  
Stephen A. Klein ◽  
Dimitra Konsta ◽  
Christine C. Nam ◽  
...  
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Evaluation Studies ◽  
Circulation Model ◽  
Community Analysis ◽  
Model Intercomparison ◽  
Cloud Feedbacks ◽  
Diagnostic Codes ◽  
Feedback Model ◽  
Intercomparison Project

Abstract. The CFMIP Diagnostic Codes Catalogue assembles cloud metrics, diagnostics and methodologies, together with programs to diagnose them from general circulation model (GCM) outputs written by various members of the CFMIP community. This aims to facilitate use of the diagnostics by the wider community studying climate and climate change. This paper describes the diagnostics and metrics which are currently in the catalogue, together with examples of their application to model evaluation studies and a summary of some of the insights these diagnostics have provided into the main shortcomings in current GCMs. Analysis of outputs from CFMIP and CMIP6 experiments will also be facilitated by the sharing of diagnostic codes via this catalogue.Any code which implements diagnostics relevant to analysing clouds – including cloud–circulation interactions and the contribution of clouds to estimates of climate sensitivity in models – and which is documented in peer-reviewed studies, can be included in the catalogue. We very much welcome additional contributions to further support community analysis of CMIP6 outputs.

Assessing the Climate Impacts of the Observed Atlantic Multidecadal Variability Using the GFDL CM2.1 and NCAR CESM1 Global Coupled Models

2017 ◽  
Vol 30 (8) ◽  
pp. 2785-2810 ◽  
Author(s):  
Yohan Ruprich-Robert ◽  
Rym Msadek ◽  
Frederic Castruccio ◽  
Stephen Yeager ◽  
Tom Delworth ◽  
...  
Keyword(s):  
North Atlantic ◽  
Climate Models ◽  
Walker Circulation ◽  
Climate Impacts ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Atlantic Multidecadal Variability ◽  
Coupled Models ◽  
Multidecadal Variability ◽  
The Pacific

The climate impacts of the observed Atlantic multidecadal variability (AMV) are investigated using the GFDL CM2.1 and the NCAR CESM1 coupled climate models. The model North Atlantic sea surface temperatures are restored to fixed anomalies corresponding to an estimate of the internally driven component of the observed AMV. Both models show that during boreal summer the AMV alters the Walker circulation and generates precipitation anomalies over the whole tropical belt. A warm phase of the AMV yields reduced precipitation over the western United States, drier conditions over the Mediterranean basin, and wetter conditions over northern Europe. During boreal winter, the AMV modulates by a factor of about 2 the frequency of occurrence of El Niño and La Niña events. This response is associated with anomalies over the Pacific that project onto the interdecadal Pacific oscillation pattern (i.e., Pacific decadal oscillation–like anomalies in the Northern Hemisphere and a symmetrical pattern in the Southern Hemisphere). This winter response is a lagged adjustment of the Pacific Ocean to the AMV forcing in summer. Most of the simulated global-scale impacts are driven by the tropical part of the AMV, except for the winter North Atlantic Oscillation–like response over the North Atlantic–European region, which is driven by both the subpolar and tropical parts of the AMV. The teleconnections between the Pacific and Atlantic basins alter the direct North Atlantic local response to the AMV, which highlights the importance of using a global coupled framework to investigate the climate impacts of the AMV. The similarity of the two model responses gives confidence that impacts described in this paper are robust.

scholarly journals Evaluating and improving the treatment of gases in radiation schemes: the Correlated K-Distribution Model Intercomparison Project (CKDMIP)

2020 ◽  
Author(s):  
Robin J. Hogan ◽  
Marco Matricardi
Keyword(s):  
General Circulation ◽  
Computational Cost ◽  
General Circulation Models ◽  
Gas Absorption ◽  
Distribution Model ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Climate Modelling ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract. Most radiation schemes in weather and climate models use the 'correlated k-distribution' (CKD) method to treat gas absorption, which approximates a broadband spectral integration by N pseudo-monochromatic calculations. Larger N means more accuracy and a wider range of gas concentrations can be simulated, but at greater computational cost. Unfortunately, the tools to perform this efficiency-accuracy trade-off (e.g., to generate separate CKD models for applications such as short-range weather forecasting to climate modelling) are unavailable to the vast majority of users of radiation schemes. This paper describes the experimental protocol for the Correlated K-Distribution Model Intercomparison Project (CKDMIP), whose purpose is to use benchmark line-by-line calculations: (1) to evaluate the accuracy of existing CKD models, (2) to explore how accuracy varies with N for CKD models submitted by CKDMIP participants, (3) to understand how different choices in way that CKD models are generated affects their accuracy for the same N, and (4) to generate freely available datasets and software facilitating the development of new gas-optics tools. The datasets consist of the high-resolution longwave and shortwave absorption spectra of nine gases for a range of atmospheric conditions, realistic and idealized. Thirty-four concentration scenarios for the well-mixed greenhouse gases are proposed to test CKD models from palaeo- to future-climate conditions. We demonstrate the strengths of the protocol in this paper by using it to evaluate the widely-used Rapid Radiative Transfer Model for General Circulation Models (RRTMG).

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