scholarly journals Toward unification of the multiscale modeling of the atmosphere

2011 ◽  
Vol 11 (8) ◽  
pp. 3731-3742 ◽  
Author(s):  
A. Arakawa ◽  
J.-H. Jung ◽  
C.-M. Wu
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
General Circulation Models ◽  
Moist Convection ◽  
Modeling Framework ◽  
Continuous Transition ◽  
Convective Clouds ◽  
Multi Scale ◽  
Scale Modeling ◽  
Deep Moist Convection

Abstract. As far as the representation of deep moist convection is concerned, only two kinds of model physics are used at present: highly parameterized as in the conventional general circulation models (GCMs) and explicitly simulated as in the cloud-resolving models (CRMs). Ideally, these two kinds of model physics should be unified so that a continuous transition of model physics from one kind to the other takes place as the resolution changes. With such unification, the GCM can converge to a global CRM (GCRM) as the grid size is refined. This paper suggests two possible routes to achieve the unification. ROUTE I continues to follow the parameterization approach, but uses a unified parameterization that is applicable to any horizontal resolutions between those typically used by GCMs and CRMs. It is shown that a key to construct such a unified parameterization is to eliminate the assumption of small fractional area covered by convective clouds, which is commonly used in the conventional cumulus parameterizations either explicitly or implicitly. A preliminary design of the unified parameterization is presented, which demonstrates that such an assumption can be eliminated through a relatively minor modification of the existing mass-flux based parameterizations. Partial evaluations of the unified parameterization are also presented. ROUTE II follows the "multi-scale modeling framework (MMF)" approach, which takes advantage of explicit representation of deep moist convection and associated cloud-scale processes by CRMs. The Quasi-3-D (Q3-D) MMF is an attempt to broaden the applicability of MMF without necessarily using a fully three-dimensional CRM. This is accomplished using a network of cloud-resolving grids with large gaps. An outline of the Q3-D algorithm and highlights of preliminary results are reviewed.

scholarly journals Toward unification of the multiscale modeling of the atmosphere

2011 ◽  
Vol 11 (1) ◽  
pp. 3181-3217 ◽  
Author(s):  
A. Arakawa ◽  
J.-H. Jung ◽  
C.-M. Wu
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
General Circulation Models ◽  
Moist Convection ◽  
Modeling Framework ◽  
Continuous Transition ◽  
Convective Clouds ◽  
Multi Scale ◽  
Deep Moist Convection ◽  
Fine Resolution

Abstract. This paper suggests two possible routes to achieve the unification of model physics in coarse- and fine-resolution atmospheric models. As far as representation of deep moist convection is concerned, only two kinds of model physics are used at present: highly parameterized as in the conventional general circulation models (GCMs) and explicitly simulated as in the cloud-resolving models (CRMs). Ideally, these two kinds of model physics should be unified so that a continuous transition of model physics from one kind to the other takes place as the resolution changes. With such unification, the GCM can converge to a global CRM (GCRM) as the grid size is refined. ROUTE I for unification continues to follow the parameterization approach, but uses a unified parameterization that is applicable to any horizontal resolutions between those typically used by GCMs and CRMs. It is shown that a key to construct such a unified parameterization is to eliminate the assumption of small fractional area covered by convective clouds, which is commonly used in the conventional cumulus parameterizations either explicitly or implicitly. A preliminary design of the unified parameterization is presented, which demonstrates that such an assumption can be eliminated through a relatively minor modification of the existing mass-flux based parameterizations. Partial evaluations of the unified parameterization are also presented. ROUTE II for unification follows the "multi-scale modeling framework (MMF)" approach, which takes advantage of explicit representation of deep moist convection and associated cloud-scale processes by CRMs. The Quasi-3-D (Q3-D) MMF is an attempt to broaden the applicability of MMF without necessarily using a fully three-dimensional CRM. This is accomplished using a network of cloud-resolving grids with gaps. An outline of the Q3-D algorithm and highlights of preliminary results are reviewed.

A Unified Representation of Deep Moist Convection in Numerical Modeling of the Atmosphere. Part II

2014 ◽  
Vol 71 (6) ◽  
pp. 2089-2103 ◽  
Author(s):  
Chien-Ming Wu ◽  
Akio Arakawa
Keyword(s):  
General Circulation ◽  
Traditional Approach ◽  
Simulated Data ◽  
Grid Cell ◽  
General Circulation Models ◽  
Horizontal Resolution ◽  
Moist Convection ◽  
Modeling Framework ◽  
Thermodynamic Variables ◽  
Deep Moist Convection

Abstract In Part I of this paper, a generalized modeling framework for representing deep moist convection was presented. The framework, called unified parameterization, effectively unifies the parameterizations in general circulation models (GCMs) and cloud-resolving models (CRMs) and thus is applicable to any horizontal resolution between those typically used in those models. The key parameter in the unification is the fractional convective cloudiness σ, which is the fractional area covered by convective updrafts in the grid cell. The central issue of Part I is to formulate the σ dependence of vertical eddy transports of thermodynamic variables and to determine σ for each realization of grid-scale processes. The present paper completes the formulation through further analysis of the simulated data. The analyzed fields include the vertical structure of the σ dependence of vertical and horizontal eddy transports of moist static energy and horizontal momentum and that of cloud microphysical sources. For the momentum transport, the analysis results clearly show the limits of the traditional approach of parameterization based on an effectively one-dimensional model. For cloud microphysical conversions, it is shown that those taking place primarily inside and outside the updrafts are roughly proportional to σ and 1 − σ, respectively.

A Comparison of the Water Budgets between Clouds from AMMA and TWP-ICE

2013 ◽  
Vol 70 (2) ◽  
pp. 487-503 ◽  
Author(s):  
Xiping Zeng ◽  
Wei-Kuo Tao ◽  
Scott W. Powell ◽  
Robert A. Houze ◽  
Paul Ciesielski ◽  
...  
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
Vertical Wind Shear ◽  
General Circulation Models ◽  
Warm Pool ◽  
Water Budgets ◽  
Convective Systems ◽  
Convective Clouds ◽  
Distinct Structure ◽  
Multidisciplinary Analysis

Abstract Two field campaigns, the African Monsoon Multidisciplinary Analysis (AMMA) and the Tropical Warm Pool–International Cloud Experiment (TWP-ICE), took place in 2006 near Niamey, Niger, and Darwin, Northern Territory, Australia, providing extensive observations of mesoscale convective systems (MCSs) near a desert and a tropical coast, respectively. Under the constraint of their observations, three-dimensional cloud-resolving model simulations are carried out and presented in this paper to replicate the basic characteristics of the observed MCSs. All of the modeled MCSs exhibit a distinct structure having deep convective clouds accompanied by stratiform and anvil clouds. In contrast to the approximately 100-km-scale MCSs observed in TWP-ICE, the MCSs in AMMA have been successfully simulated with a scale of about 400 km. These modeled AMMA and TWP-ICE MCSs offer an opportunity to understand the structure and mechanism of MCSs. Comparing the water budgets between AMMA and TWP-ICE MCSs suggests that TWP-ICE convective clouds have stronger ascent while the mesoscale ascent outside convective clouds in AMMA is stronger. A case comparison, with the aid of sensitivity experiments, also suggests that vertical wind shear and ice crystal (or dust aerosol) concentration can significantly impact stratiform and anvil clouds (e.g., their areas) in MCSs. In addition, the obtained water budgets quantitatively describe the transport of water between convective, stratiform, and anvil regions as well as water sources/sinks from microphysical processes, providing information that can be used to help determine parameters in the convective and cloud parameterizations in general circulation models (GCMs).

scholarly journals The Goddard multi-scale modeling system with unified physics

2009 ◽  
Vol 27 (8) ◽  
pp. 3055-3064 ◽  
Author(s):  
W.-K. Tao ◽  
D. Anderson ◽  
J. Chern ◽  
J. Entin ◽  
A. Hou ◽  
...  
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Regional Scale ◽  
Circulation Model ◽  
Scale Model ◽  
Modeling Framework ◽  
Multi Scale ◽  
Scale Modeling ◽  
Simulated Precipitation ◽  
Multi Scale Modeling

Abstract. Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (CRM), (2) a regional-scale model, the NASA unified Weather Research and Forecasting Model (WRF), and (3) a coupled CRM-GCM (general circulation model, known as the Goddard Multi-scale Modeling Framework or MMF). The same cloud-microphysical processes, long- and short-wave radiative transfer and land-surface processes are applied in all of the models to study explicit cloud-radiation and cloud-surface interactive processes in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator for comparison and validation with NASA high-resolution satellite data. This paper reviews the development and presents some applications of the multi-scale modeling system, including results from using the multi-scale modeling system to study the interactions between clouds, precipitation, and aerosols. In addition, use of the multi-satellite simulator to identify the strengths and weaknesses of the model-simulated precipitation processes will be discussed as well as future model developments and applications.

scholarly journals Investigating the impact of land surface characteristics on monsoon dynamics with idealized model simulations and theories

2021 ◽  
pp. 1-49
Author(s):  
Jane E. Smyth ◽  
Yi Ming
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Circulation Model ◽  
South American ◽  
Moist Convection ◽  
Modeling Framework ◽  
Dry Land ◽  
Near Surface ◽  
Deep Moist Convection ◽  
The Impact

AbstractMonsoons emerge over a range of land surface conditions and exhibit varying physical characteristics over the seasonal cycle, from onset to withdrawal. Systematically varying the moisture and albedo parameters over land in an idealized modeling framework allows one to analyze the physics underlying the successive stages of monsoon development. To this end we implement an isolated South American continent with reduced heat capacity but no topography in an idealized moist general circulation model. Irrespective of the local moisture availability, the seasonal cycles of precipitation and circulation over the South American monsoon sector are distinctly monsoonal with the default surface albedo. The dry land case (zero evaporation) is characterized by a shallow overturning circulation with vigorous lower-tropospheric ascent, transporting water vapor from the ocean. By contrast, with bucket hydrology or unlimited land moisture the monsoon features deep moist convection that penetrates the upper troposphere. A series of land albedo perturbation experiments indicates that the monsoon strengthens with the net column energy flux and the near-surface moist static energy with all land moisture conditions. When the land-ocean thermal contrast is strong enough, inertial instability alone is sufficient for producing a shallow but vigorous circulation and converging a large amount of moisture from the ocean even in the absence of land moisture. Once the land is sufficiently moist, convective instability takes hold and the shallow circulation deepens. These results have implications for monsoon onset and intensification, and may elucidate the seasonal variations in how surface warming impacts tropical precipitation over land.

scholarly journals A Theory for Buoyancy and Velocity Scales in Deep Moist Convection

2009 ◽  
Vol 66 (11) ◽  
pp. 3449-3463 ◽  
Author(s):  
Antonio Parodi ◽  
Kerry Emanuel
Keyword(s):  
Three Dimensional ◽  
Wrf Model ◽  
Domain Size ◽  
Terminal Velocity ◽  
Statistical Equilibrium ◽  
Limited Area ◽  
Moist Convection ◽  
Convective Structures ◽  
Convective Clouds ◽  
Deep Moist Convection

Abstract Buoyancy and velocity scales for dry convection in statistical equilibrium were derived in the early twentieth century by Prandtl, but the scaling of convective velocity and buoyancy, as well as the fractional area coverage of convective clouds, is still unresolved for moist convection. In this paper, high-resolution simulations of an atmosphere in radiative–convective equilibrium are performed using the Weather Research and Forecasting (WRF) model, a three-dimensional, nonhydrostatic, convection-resolving, limited-area model. The velocity and buoyancy scales for moist convection in statistical equilibrium are characterized by prescribing different constant cooling rates to the system. It is shown that the spatiotemporal properties of deep moist convection and buoyancy and velocity scales at equilibrium depend on the terminal velocity of raindrops and a hypothesis is developed to explain this behavior. This hypothesis is evaluated and discussed in the context of the numerical results provided by the WRF model. The influence of domain size on radiative–convective equilibrium statistics is also assessed. The dependence of finescale spatiotemporal properties of convective structures on numerical and physical details is investigated.

Multi-Axial Homogenized Energy Model for Ferroelectric Materials

Aerospace ◽  
2006 ◽  
Author(s):  
William S. Oates ◽  
Ralph C. Smith
Keyword(s):  
Domain Switching ◽  
Three Dimensional ◽  
Ferroelectric Materials ◽  
Energy Model ◽  
Modeling Framework ◽  
Multi Scale ◽  
Modeling Approach ◽  
Scale Modeling ◽  
Multi Scale Modeling ◽  
Homogenized Energy Model

A multi-axial homogenized energy model is developed to account for nonlinear and hysteretic ferroelectric constitutive behavior induced by multi-axial electric field loading. The modeling approach extends a one-dimensional multi-scale modeling framework developed for ferroic materials [1, 2]. A three-dimensional energy function is introduced at the mesoscopic length scale and subsequently approximated as piecewise polynomial approximations to improve computational efficiency. Multi-scale field relations are then developed by introducing a distribution of effective electric fields and coercive fields that govern the nucleation of localized domain switching in polycrystalline ferroelectric materials. The distribution of field relations is used to relate the localized domain switching processes to observed macroscopic behavior by utilizing a stochastic homogenization technique. It is demonstrated that a simplified stochastic distribution of effective fields and coercive fields is sufficient to predict multi-axial ferroelectric switching in ferroelectric ceramics. Examples are given to validate the model in comparison to multi-axial loading experiments given in the literature. The model reduction provides a simple and efficient multi-scale modeling approach that is important for developing reliable piezoelectric actuator systems as well as implementation in model-based control of two and three dimensional structures.

A novel synergistic multi-scale modeling framework to predict micro- and meso-scale damage behaviors of 2D triaxially braided composite

2021 ◽  
pp. 105678952110339
Author(s):  
Hongyong Jiang ◽  
Yiru Ren ◽  
Qiduo Jin
Keyword(s):  
Compressive Load ◽  
Scale Model ◽  
Modeling Framework ◽  
Braided Composite ◽  
Multi Scale ◽  
Scale Modeling ◽  
Bridge Model ◽  
Multi Scale Modeling ◽  
Transverse Damage ◽  
Meso Scale

A novel synergistic multi-scale modeling framework with a coupling of micro- and meso-scale is proposed to predict damage behaviors of 2D-triaxially braided composite (2DTBC). Based on the Bridge model, the internal stress and micro damage of constituent materials are respectively coupled with the stress and damage of tow. The initial effective elastic properties of tow (IEEP) used as the predefined data are estimated by micro-mechanics models. Due to in-situ effects, stress concentration factor (SCF) is considered in the micro matrix, exhibiting progressive damage accumulation. Comparisons of IEEP and strengths between the Bridge and Chamis’ theory are conducted to validate the values of IEEP and SCF. Based on the representative volume element (RVE), the macro properties and damage modes of 2DTBC are predicted to be consistent with available experiments and meso-scale simulation. Both axial and transverse damage mechanisms of 2DTBC under tensile or compressive load are revealed. Micro fiber and matrix damage accumulations have significant effects on the meso-scale axial and transverse damage of tows due to multi-scale coupling effects. Different from existing meso-/multi-scale models, the proposed multi-scale model can capture a crucial phenomenon that the transverse damage of tow is vulnerable to micro fiber fracture. The proposed multi-scale framework provides a robust tool for future systematic studies on constituent materials level to larger-scale aeronautical materials.

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