The atmospheric general circulation model with a hybrid vertical coordinate

2014 ◽  
Vol 29 (6) ◽  
Author(s):  
Dmitry V. Kulyamin ◽  
Valentin P. Dymnikov
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
Numerical Algorithms ◽  
Circulation Model ◽  
Observation Data ◽  
Three Dimensional Model ◽  
Vertical Coordinate ◽  
Equivalence Of Algorithms ◽  
Comparison Of The Results ◽  
Climatic Characteristics

AbstractThe paper presents a new version of the three-dimensional model of general circulation of Earth troposphere-stratosphere-mesosphere (for altitudes up to 90 km from the surface) with a hybrid vertical coordinate. A method of vertical discretization is developed according to the numerical algorithms and preserving the equivalence of algorithms used in previous models. An algorithm of semi-implicit integration in time is proposed. The new version of the model adequately represents climatic characteristics,which are confirmed by comparison of the results of numerical experiments with observation data and with the previous version of the atmospheric circulation model using sigma-coordinates.

scholarly journals WAVETRISK-1.0: an adaptive wavelet hydrostatic dynamical core

2019 ◽  
Author(s):  
Nicholas K.-R. Kevlahan ◽  
Thomas Dubos
Keyword(s):  
Shallow Water ◽  
General Circulation ◽  
Wave Train ◽  
Shallow Water Equation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Time Step ◽  
Adaptive Wavelet ◽  
Dynamical Core ◽  
Vertical Coordinate

Abstract. This paper presents the new adaptive dynamical core wavetrisk. The fundamental features of the wavelet-based adaptivity were developed for the shallow water equation on the β-plane in Dubos and Kevlahan (2013) and extended to the icosahedral grid on the sphere in Aechtner et al. (2015). The three-dimensional dynamical core solves the compressible hydrostatic multilayer rotating shallow water equations on a multiscale dynamically adapted grid. The equations are discretized using a Lagrangian vertical coordinate version of dynamico introduced in Dubos et al. (2015). The horizontal computational grid is adapted at each time step to ensure a user-specified relative error in either the tendencies or the solution. The Lagrangian vertical grid is remapped using an adaptive Lagrangian-Eulerian (ALE) algorithm onto the initial hybrid σ pressure-based coordinates as necessary. The resulting grid is adapted horizontally, but uniform over all vertical layers. Thus, the three-dimensional grid is a set of columns of varying sizes. The code is parallelized by domain decomposition using mpi and the variables are stored in a hybrid data structure of dyadic quad trees and patches. A low storage explicit fourth order Runge-Kutta scheme is used for time integration. Validation results are presented for three standard dynamical core test cases: mountain-induced Rossby wave train, baroclinic instability of a jet stream and the Held and Suarez simplified general circulation model. The results confirm good strong parallel scaling and demonstrate that wavetrisk can achieve grid compression ratios of several hundred times compared with an equivalent static grid model.

scholarly journals Sensitivity of the ocean circulation model to the k–omega vertical turbulence parametrization

2019 ◽  
Vol 55 (5) ◽  
pp. 103-113
Author(s):  
V. B. Zalesny ◽  
S. N. Moshonkin
Keyword(s):  
Ocean Circulation ◽  
General Circulation ◽  
Splitting Method ◽  
Three Dimensional ◽  
Numerical Algorithms ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Turbulence Parametrization ◽  
Vertical Turbulence ◽  
Model Equations

Ocean general circulation model (OGCM) of the INM RAS with embedded k turbulent model is developed. The solution of the k model equations depends on the frequencies of buoyancy and velocity shift which are generated by the OGCM. The coefficients of vertical turbulence in OGCM depend on k and omega. The numerical algorithms of both models are based on the splitting method for physical processes. The model equations are split into two stages, describing the three-dimensional transport-diffusion of the kinetic energy of turbulence and frequency and their local generation-dissipation. The system of ordinary differential equations arising at the second stage is solved analytically, which ensures the efficiency of the algorithm. Analytical solution also written for the vertical turbulence coefficient equation. The model is used to study the sensitivity of the model circulation of the North AtlanticArctic Ocean to variations in the parameters of vertical turbulence. Experiments show that varying the coefficients of the analytical model solution can improve the adequacy of the simulation.

scholarly journals Using Different Formulations of the Transformed Eulerian Mean Equations and Eliassen–Palm Diagnostics in General Circulation Models

2010 ◽  
Vol 67 (6) ◽  
pp. 1983-1995 ◽  
Author(s):  
Steven C. Hardiman ◽  
David G. Andrews ◽  
Andy A. White ◽  
Neal Butchart ◽  
Ian Edmond
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
General Circulation Models ◽  
Primitive Equations ◽  
Model Output ◽  
Vertical Coordinate ◽  
Order Of Magnitude ◽  
Transformed Eulerian Mean

Abstract Transformed Eulerian mean (TEM) equations and Eliassen–Palm (EP) flux diagnostics are presented for the general nonhydrostatic, fully compressible, deep atmosphere formulation of the primitive equations in spherical geometric coordinates. The TEM equations are applied to a general circulation model (GCM) based on these general primitive equations. It is demonstrated that a naive application in this model of the widely used approximations to the EP diagnostics, valid for the hydrostatic primitive equations using log-pressure as a vertical coordinate and presented, for example, by Andrews et al. in 1987 can lead to misleading features in these diagnostics. These features can be of the same order of magnitude as the diagnostics themselves throughout the winter stratosphere. Similar conclusions are found to hold for “downward control” calculations. The reasons are traced to the change of vertical coordinate from geometric height to log-pressure. Implications for the modeling community, including comparison of model output with that from reanalysis products available only on pressure surfaces, are discussed.

scholarly journals Operational ocean models in the Adriatic Sea: a skill assessment

Ocean Science ◽  
2008 ◽  
Vol 4 (1) ◽  
pp. 61-71 ◽  
Author(s):  
J. Chiggiato ◽  
P. Oddo
Keyword(s):  
General Circulation ◽  
Mean Squared Error ◽  
Three Dimensional ◽  
Circulation Model ◽  
Remote Sensing Data ◽  
Skill Assessment ◽  
Regional Models ◽  
Operational Systems ◽  
Forecasting System ◽  
The Mediterranean

Abstract. In the framework of the Mediterranean Forecasting System (MFS) project, the performance of regional numerical ocean forecasting systems is assessed by means of model-model and model-data comparison. Three different operational systems considered in this study are: the Adriatic REGional Model (AREG); the Adriatic Regional Ocean Modelling System (AdriaROMS) and the Mediterranean Forecasting System General Circulation Model (MFS-GCM). AREG and AdriaROMS are regional implementations (with some dedicated variations) of POM and ROMS, respectively, while MFS-GCM is an OPA based system. The assessment is done through standard scores. In situ and remote sensing data are used to evaluate the system performance. In particular, a set of CTD measurements collected in the whole western Adriatic during January 2006 and one year of satellite derived sea surface temperature measurements (SST) allow to asses a full three-dimensional picture of the operational forecasting systems quality during January 2006 and to draw some preliminary considerations on the temporal fluctuation of scores estimated on surface quantities between summer 2005 and summer 2006. The regional systems share a negative bias in simulated temperature and salinity. Nonetheless, they outperform the MFS-GCM in the shallowest locations. Results on amplitude and phase errors are improved in areas shallower than 50 m, while degraded in deeper locations, where major models deficiencies are related to vertical mixing overestimation. In a basin-wide overview, the two regional models show differences in the local displacement of errors. In addition, in locations where the regional models are mutually correlated, the aggregated mean squared error was found to be smaller, that is a useful outcome of having several operational systems in the same region.

scholarly journals Simulation of satellite lidar and radiometer retrievals of a general circulation model three-dimensional cloud data set

1998 ◽  
Vol 103 (D20) ◽  
pp. 26025-26039 ◽  
Author(s):  
M. Doutriaux-Boucher ◽  
J. Pelon ◽  
V. Trouillet ◽  
G. Sèze ◽  
H. Le Treut ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Data Set ◽  
Cloud Data

scholarly journals A quasi three dimensional model of water flow in the subsurface of Milano (Italy): the stationary flow

2000 ◽  
Vol 4 (1) ◽  
pp. 113-124 ◽  
Author(s):  
M. Giudici ◽  
L. Foglia ◽  
G. Parravicini ◽  
G. Ponzini ◽  
B. Sincich
Keyword(s):  
Water Table ◽  
Water Demand ◽  
Three Dimensional ◽  
Stationary Flow ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Predictive Tool ◽  
Aquifer System ◽  
Conservative Finite Difference Scheme ◽  
Comparison Of The Results

Abstract. A quasi three-dimensional model is developed to simulate the behaviour of the aquifer system which is the resource of drinkable water for the town of Milano (Italy). Non continuous semipermeable layers locally separate permeable levels in a multilayered system, consisting of a phreatic and three confined aquifers. The numerical model is a conservative finite difference scheme based on the discretisation of the water balance equation for stationary flow. The grid spacing is 500 m and has been chosen, taking into account the distribution of the data in an area of about 400 km2. The model has been calibrated with a "trial and error" procedure, by comparison of the results of the model with the observations for three years (1950, 1974 and 1982) which correspond to different flow situations. Once calibrated, the model has been used as a predictive tool, to forecast the behaviour of the aquifer system for other years of the 20th century; the comparison between the model forecasts and observations is good. The model is capable of describing both the strong drawdown of the water table in the 1970s, when the water demand for domestic and industrial needs was very high, and the rise of the water table in the 1990s, when water extraction decreased. The results of the model confirm that the phreatic level is controlled largely by the local extraction of water; moreover, the aquifer system reacts to an increasing water demand with a small increase of the inflow and with a strong decrease of the outflow from its boundaries.

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