Description of the NCAR Community Climate Model (CCM3)

Kiehl, Tim-Rasmus; Hack, James J.; Bonan, Bertrand; Boville, A.; Briegleb, P.; Williamson, L.; Rasch, Joel

doi:10.5065/d6ff3q99

Cited by 145 publications

(12 citation statements)

References 32 publications

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“…The radiation scheme is that of the Community Atmosphere Model 3 (Collins et al 2004), which computes longwave and shortwave radiative heating rate at each level of each column every 15 time steps; the subgrid-scale scheme is the SAM Smagorinsky scheme, which is the stationary version of a prognostic scheme based on turbulent kinetic energy, the implementation of which is described in Deardorff (1980); and the microphysics scheme is the SAM single-moment microphysics (Khairoutdinov and Randall 2003), which computes the sum of nonprecipitating liquid and ice water and water vapor mixing ratio and the total precipitation mixing ratio. The surface fluxes are computed with bulk formulas with exchange coefficients calculated using the Monin-Obukhov theory, with code adapted from NCAR's Community Climate Model 3 (Kiehl et al 1996). SAM does not have a parameterization scheme for the boundary layer.…”

Section: B Model and Experiments Setupmentioning

confidence: 99%

Spontaneous Cyclogenesis without Radiative and Surface-Flux Feedbacks

Ramírez

Yang

2021

Journal of the Atmospheric Sciences

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Tropical cyclones (TCs) are among the most intense and feared storms in the world. What physical processes lead to cyclogenesis remains the most mysterious aspect of TC physics. Here, we study spontaneous TC genesis in rotating radiative-convective equilibrium using cloud-resolving simulations over an f-plane with constant sea-surface temperature. Previous studies proposed that spontaneous TC genesis requires either radiative or surface-flux feedbacks. To test this hypothesis, we perform mechanism-denial experiments, in which we switch off both feedback processes in numerical simulations. We find that TCs can self-emerge even without radiative and surface-flux feedbacks. Although these feedbacks accelerate the genesis and impact the size of the TCs, TCs in the experiments without them can reach similar intensities as those in the control experiment. We show that TC genesis is associated with an increase in the Available Potential Energy (APE); and that convective heating dominates the APE production. Our result suggests that spontaneous TC genesis may result from a cooperative interaction between convection and circulation, and that radiative and surface-flux feedbacks accelerate the process. Furthermore, we find that increasing the planetary rotation favors spontaneous TC genesis.

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Section: B Model and Experiments Setupmentioning

confidence: 99%

Spontaneous Cyclogenesis without Radiative and Surface-Flux Feedbacks

Ramírez

Yang

2021

Journal of the Atmospheric Sciences

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“…It has an exponential relaxing scheme for the lateral boundary that allows a smooth transition between inside domain model forecasting and the lateral boundary conditions (Giorgi et al, 1993). For the atmospheric radiative transfer, RegCM4 uses the same scheme of Community Climate Model (CCM3; Kiehl et al, 1996), being the heating rate and the atmospheric fluxes computed in distinct ways for solar and terrestrial radiation, for clear and cloudy sky.…”

Section: Modelmentioning

confidence: 99%

The combined influences of Amazon deforestation and Pacific Decadal Oscillation on the South America climate variability

Silva

Rocha

Pereira

et al. 2023

Intl Journal of Climatology

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In this study we analyse the climatic impact over South America due to Amazon deforestation for positive (PDO+) and negative (PDO−) PDO phases. The regional climatic model RegCM4 was run from 1968 to 2003 for the domain including a great area of the Pacific Ocean and South America, using 50 km as spatial resolution. The Amazon deforestation scenario is that one extrapolated to the 2050 year. Under deforestation, the results show precipitation depletion over the extreme northern South America and precipitation increase over areas to the south, including deforested pixels and east‐southern sectors. These changes are more intense and occupy larger areas during the rainy season. Simulations also indicate that deforestation may impose a drier corridor following the Andes Mountains oriental slopes, from northwestern to south‐southeastern South America, in the rainy season. The impact from deforestation in distinct PDO phases presents the greatest signals over central‐southern South America, in a northwest–southeast direction. Over southeast Brazil, deforestation presents a slightly northeastward displacement of the PDO+ positive precipitation anomalies, intensifying the precipitation anomalies in the north sector and weakening over the south sector. The deforestation effects are more intense in the rainy season and have opposite signals between PDO+ and PDO−. Over the southeast South America, deforestation provides a weaker signal on PDO+ negative precipitation than in PDO−. The increased air temperature over the northern South America, near the northern coast, due to the joint effect of deforestation and PDO variability is more evident during PDO+ dry season than PDO− rainy season. This study illustrates the importance of considering long‐term climate simulations to better understand the role of deforestation in the lower frequency variability over South America.

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“…All simulations share the non-hydrostatic dynamical core [60]. RegCM4-NH uses the following physics schemes: UW-PBL scheme [63], Tiedtke Cumulus convection scheme [64][65][66], Subex moisture scheme [67], CCSM radiation scheme [68], CLM4.5 Land surface [69], and Zeng Ocean Flux scheme [70]. CP-RegCM4-NH uses the same schemes except for Holstag PBL scheme [71]); the deep cumulus convection is switched off, but a simplified Tiedtke Cumulus scheme is used for triggering non-precipitating shallow convection, with a WSM5 scheme for microphysics [72].…”

Section: Model Simulationsmentioning

confidence: 99%

Non-Hydrostatic Regcm4 (Regcm4-NH): Evaluation of Precipitation Statistics at the Convection-Permitting Scale over Different Domains

et al. 2022

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Recent studies over different geographical regions of the world have proven that regional climate models at the convection-permitting scale (CPMs) improve the simulation of precipitation in many aspects, such as the diurnal cycle, precipitation frequency, intensity, and extremes at daily—but even more at hourly—time scales. Here, we present an evaluation of climate simulations with the newly developed RegCM4-NH model run at the convection-permitting scale (CP-RegCM4-NH) for a decade-long period, over three domains covering a large European area. The simulations use a horizontal grid spacing of ~3 km and are driven by the ERA-Interim reanalysis through an intermediate driving RegCM4-NH simulation at ~12 km grid spacing with parameterized deep convection. The km-scale simulations are evaluated against a suite of hourly observation datasets with high spatial resolutions and are compared to the coarse-resolution driving simulation in order to assess improvements in precipitation from the seasonal to hourly scale. The results show that CP-RegCM4-NH produces a more realistic representation of precipitation than the coarse-resolution simulation over all domains. The most significant improvements were found for intensity, heavy precipitation, and precipitation frequency, both on daily and hourly time scales in all seasons. In general, CP-RegCM4-NH tends to correctly produce more intense precipitation and to reduce the frequency of events compared to the coarse-resolution one. On the daily scale, improvements in CP simulations are highly region dependent, with the best results over Italy, France, and Germany, and the largest biases over Switzerland, the Carpathians, and Greece, especially during the summer seasons. At the hourly scale, the improvement in CP simulations for precipitation intensity and spatial distribution is clearer than at the daily timescale. In addition, the representation of extreme events is clearly improved by CP-RegCM4-NH, particularly at the hourly time scale, although an overestimation over some subregions can be found. Although biases between the model simulations at the km-scale and observations still exist, this first application of CP-RegCM4-NH at high spatial resolution indicates a clear benefit of convection-permitting simulations and encourages further assessments of the added value of km-scale model configurations for regional climate change projections.

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Description of the NCAR Community Climate Model (CCM3)

Cited by 145 publications

References 32 publications

Spontaneous Cyclogenesis without Radiative and Surface-Flux Feedbacks

Spontaneous Cyclogenesis without Radiative and Surface-Flux Feedbacks

The combined influences of Amazon deforestation and Pacific Decadal Oscillation on the South America climate variability

Non-Hydrostatic Regcm4 (Regcm4-NH): Evaluation of Precipitation Statistics at the Convection-Permitting Scale over Different Domains

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