A bulk mass flux convection scheme for climate model: description and moisture sensitivity

2011 ◽  
Vol 38 (1-2) ◽  
pp. 411-429 ◽  
Author(s):  
Daehyun Kim ◽  
In-Sik Kang
Keyword(s):  
Mass Flux ◽  
Climate Model ◽  
Model Description ◽  
Convection Scheme ◽  
Moisture Sensitivity ◽  
Bulk Mass

scholarly journals Bulk Mass-Flux Perturbation Formulation for a Unified Approach of Deep Convection at High Resolution

2015 ◽  
Vol 143 (10) ◽  
pp. 4038-4063 ◽  
Author(s):  
Luc Gerard
Keyword(s):  
Mass Flux ◽  
Deep Convection ◽  
Limited Area ◽  
Perturbation Approach ◽  
Unified Approach ◽  
Convection Scheme ◽  
Bulk Mass ◽  
Simplifying Assumptions ◽  
Model Cloud ◽  
The Mean

Abstract Parameterizing deep convection at model resolutions of a few kilometers or less requires diverging from several simplifying assumptions valid at coarser resolutions. The separation or complementarity between the deep-convection scheme and the model cloud scheme must be addressed properly to prevent a double counting of some phenomena, account for evolution in time, and keep consistent results while approaching resolutions where deep convection can be treated explicitly (without parameterization). In this paper, the author formulates and tests a perturbation approach of the bulk mass-flux representation of deep convective updrafts and downdrafts. The subgrid deep-convection scheme represents only the effect of the unresolved part of the real updrafts, complementing an explicit part associated with the mean gridbox vertical velocity. Special attention is paid to the ordering and interactions of the moist parameterizations, the formulation of the closure and of the triggering, and the accounting of time evolution aspects. The multiresolution behavior of the scheme is assessed in the operational numerical prediction model ALARO [a version of the Action de Recherche Petite Echelle Grande Echelle-Aire Limitée Adaptation Dynamique Développement International (ARPEGE-ALADIN) operational limited area model with a revised and modular structure of the physical parameterizations]. Unlike most mass-flux schemes, the parameterized part gradually fades out when the model resolution is increased, allowing the results to approach those of an explicit treatment of deep convection.

scholarly journals The GFDL Global Atmospheric Chemistry-Climate Model AM4.1: Model Description and Simulation Characteristics

2020 ◽  
Author(s):  
Larry Wayne Horowitz ◽  
Vaishali Naik ◽  
Fabien Paulot ◽  
Paul A Ginoux ◽  
John P Dunne ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Model Description

scholarly journals The UVic earth system climate model: Model description, climatology, and applications to past, present and future climates

2001 ◽  
Vol 39 (4) ◽  
pp. 361-428 ◽  
Author(s):  
Andrew J. Weaver ◽  
Michael Eby ◽  
Edward C. Wiebe ◽  
Cecilia M. Bitz ◽  
Phil B. Duffy ◽  
...  
Keyword(s):  
Climate Model ◽  
Model Description ◽  
Earth System

scholarly journals The FAMOUS climate model (versions XFXWB and XFHCC): description update to version XDBUA

2011 ◽  
Vol 4 (4) ◽  
pp. 3047-3065
Author(s):  
R. S. Smith
Keyword(s):  
Water Budget ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Model Description ◽  
Model Intercomparison ◽  
Ocean Atmosphere ◽  
Atmosphere General Circulation Model ◽  
Intercomparison Project ◽  
The Uk

Abstract. FAMOUS is an ocean-atmosphere general circulation model of low resolution, based on version 4.5 of the UK MetOffice Unified Model. Here we update the model description to account for changes in the model as it is used in the CMIP5 EMIC model intercomparison project (EMICmip) and a number of other studies. Most of these changes correct errors found in the code. The EMICmip version of the model (XFXWB) has a better-conserved water budget and additional cooling in some high latitude areas, but otherwise has a similar climatology to previous versions of FAMOUS. A variant of XFXWB is also described, with changes to the dynamics at the top of the model which improve the model climatology (XFHCC).

scholarly journals Simulated Anthropogenic Changes in the Brewer–Dobson Circulation, Including Its Extension to High Latitudes

2009 ◽  
Vol 22 (6) ◽  
pp. 1516-1540 ◽  
Author(s):  
Charles McLandress ◽  
Theodore G. Shepherd
Keyword(s):  
Climate Change ◽  
Mass Flux ◽  
Planetary Wave ◽  
Climate Model ◽  
Middle Atmosphere ◽  
Wave Drag ◽  
Latitude Range ◽  
Relative Contribution ◽  
Transient Simulations ◽  
Change Response

Abstract Recent studies using comprehensive middle atmosphere models predict a strengthening of the Brewer–Dobson circulation in response to climate change. To gain confidence in the realism of this result it is important to quantify and understand the contributions from the different components of stratospheric wave drag that cause this increase. Such an analysis is performed here using three 150-yr transient simulations from the Canadian Middle Atmosphere Model (CMAM), a Chemistry–Climate Model that simulates climate change and ozone depletion and recovery. Resolved wave drag and parameterized orographic gravity wave drag account for 60% and 40%, respectively, of the long-term trend in annual mean net upward mass flux at 70 hPa, with planetary waves accounting for 60% of the resolved wave drag trend. Synoptic wave drag has the strongest impact in northern winter, where it accounts for nearly as much of the upward mass flux trend as planetary wave drag. Owing to differences in the latitudinal structure of the wave drag changes, the relative contribution of resolved and parameterized wave drag to the tropical upward mass flux trend over any particular latitude range is highly sensitive to the range of latitudes considered. An examination of the spatial structure of the climate change response reveals no straightforward connection between the low-latitude and high-latitude changes: while the model results show an increase in Arctic downwelling in winter, they also show a decrease in Antarctic downwelling in spring. Both changes are attributed to changes in the flux of stationary planetary wave activity into the stratosphere.

scholarly journals Emulating coupled atmosphere-ocean and carbon cycle models with a simpler model, MAGICC6 – Part 1: Model description and calibration

2011 ◽  
Vol 11 (4) ◽  
pp. 1417-1456 ◽  
Author(s):  
M. Meinshausen ◽  
S. C. B. Raper ◽  
T. M. L. Wigley
Keyword(s):  
Carbon Cycle ◽  
General Circulation ◽  
Climate Model ◽  
General Circulation Models ◽  
Climate System ◽  
Model Description ◽  
Ocean Heat Uptake ◽  
The Mean ◽  
Sres Scenarios ◽  
Ipcc Sres

Abstract. Current scientific knowledge on the future response of the climate system to human-induced perturbations is comprehensively captured by various model intercomparison efforts. In the preparation of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC), intercomparisons were organized for atmosphere-ocean general circulation models (AOGCMs) and carbon cycle models, named "CMIP3" and "C4MIP", respectively. Despite their tremendous value for the scientific community and policy makers alike, there are some difficulties in interpreting the results. For example, radiative forcings were not standardized across the various AOGCM integrations and carbon cycle runs, and, in some models, key forcings were omitted. Furthermore, the AOGCM analysis of plausible emissions pathways was restricted to only three SRES scenarios. This study attempts to address these issues. We present an updated version of MAGICC, the simple carbon cycle-climate model used in past IPCC Assessment Reports with enhanced representation of time-varying climate sensitivities, carbon cycle feedbacks, aerosol forcings and ocean heat uptake characteristics. This new version, MAGICC6, is successfully calibrated against the higher complexity AOGCMs and carbon cycle models. Parameterizations of MAGICC6 are provided. The mean of the emulations presented here using MAGICC6 deviates from the mean AOGCM responses by only 2.2% on average for the SRES scenarios. This enhanced emulation skill in comparison to previous calibrations is primarily due to: making a "like-with-like comparison" using AOGCM-specific subsets of forcings; employing a new calibration procedure; as well as the fact that the updated simple climate model can now successfully emulate some of the climate-state dependent effective climate sensitivities of AOGCMs. The diagnosed effective climate sensitivity at the time of CO2 doubling for the AOGCMs is on average 2.88 °C, about 0.33 °C cooler than the mean of the reported slab ocean climate sensitivities. In the companion paper (Part 2) of this study, we examine the combined climate system and carbon cycle emulations for the complete range of IPCC SRES emissions scenarios and the new RCP pathways.

scholarly journals Role of the Convection Scheme in Modeling Initiation and Intensification of Tropical Depressions over the North Atlantic

2017 ◽  
Vol 145 (4) ◽  
pp. 1495-1509 ◽  
Author(s):  
J.-P. Duvel ◽  
S. J. Camargo ◽  
A. H. Sobel
Keyword(s):  
Relative Humidity ◽  
Climate Model ◽  
Early Stage ◽  
Global Climate ◽  
Global Climate Model ◽  
Convective Available Potential Energy ◽  
Convective Precipitation ◽  
Cloud Base ◽  
Entrainment Rate ◽  
Convection Scheme

Abstract The authors analyze how modifications of the convective scheme modify the initiation of tropical depression vortices (TDVs) and their intensification into stronger warm-cored tropical cyclone–like vortices (TCs) in global climate model (GCM) simulations. The model’s original convection scheme has entrainment and cloud-base mass flux closures based on moisture convergence. Two modifications are considered: one in which entrainment is dependent on relative humidity and another in which the closure is based on the convective available potential energy (CAPE). Compared to reanalysis, TDVs are more numerous and intense in all three simulations, probably as a result of excessive parameterized deep convection at the expense of convection detraining at midlevel. The relative humidity–dependent entrainment rate increases both TDV initiation and intensification relative to the control. This is because this entrainment rate is reduced in the moist center of the TDVs, giving more intense convective precipitation, and also because it generates a moister environment that may favor the development of early stage TDVs. The CAPE closure inhibits the parameterized convection in strong TDVs, thus limiting their development despite a slight increase in the resolved convection. However, the maximum intensity reached by TC-like TDVs is similar in the three simulations, showing the statistical character of these tendencies. The simulated TCs develop from TDVs with different dynamical origins than those observed. For instance, too many TDVs and TCs initiate near or over southern West Africa in the GCM, collocated with the maximum in easterly wave activity, whose characteristics are also dependent on the convection scheme considered.

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