OSIRIS observations of a tongue of NOx in the lower stratosphere at the Antarctic vortex edge: comparison with a high-resolution simulation from the Global Environmental Multiscale (GEM) model

2007 ◽  
Vol 85 (11) ◽  
pp. 1195-1207 ◽  
Author(s):  
C E Sioris ◽  
S Chabrillat ◽  
C A McLinden ◽  
C S Haley ◽  
Y J Rochon ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Three Dimensional ◽  
Multiscale Model ◽  
Dimensional Structure ◽  
Small Scale ◽  
Breaking Wave ◽  
Austral Spring ◽  
Global Environmental ◽  
The Antarctic ◽  
Global Environmental Multiscale

Selected NOx profiles of the Antarctic lower stratosphere inferred from OSIRIS NO2 observations are presented from the austral spring of 2003. These observations show a tongue of NOx at 100 hPa, with a concentration typical of the middle stratosphere. Simulations with the Global Environmental Multiscale model show that this small-scale tongue of NOx-rich air descended into the lower stratosphere. The tongue was formed as a result of a Rossby wave breaking days earlier, transporting NOx from the pole, where larger concentrations had recently appeared, to the edge of the vortex. The three-dimensional structure of the breaking wave is illustrated in detail. PACS Nos.: 92.60.hf, 92.60.Xg, 93.30.Ca

Atmospheric Factors Governing Banded Orographic Convection

2005 ◽  
Vol 62 (10) ◽  
pp. 3758-3774 ◽  
Author(s):  
Daniel J. Kirshbaum ◽  
Dale R. Durran
Keyword(s):  
Three Dimensional ◽  
Heavy Precipitation ◽  
Thermal Fluctuations ◽  
Dominant Mode ◽  
Vertical Shear ◽  
Dimensional Structure ◽  
Small Scale ◽  
Atmospheric Structure ◽  
Orographic Convection ◽  
Orographic Cloud

Abstract The three-dimensional structure of shallow orographic convection is investigated through simulations performed with a cloud-resolving numerical model. In moist flows that overcome a given topographic barrier to form statically unstable cap clouds, the organization of the convection depends on both the atmospheric structure and the mechanism by which the convection is initiated. Convection initiated by background thermal fluctuations embedded in the flow over a smooth mountain (without any small-scale topographic features) tends to be cellular and disorganized except that shear-parallel bands may form in flows with strong unidirectional vertical shear. The development of well-organized bands is favored when there is weak static instability inside the cloud and when the dry air surrounding the cloud is strongly stable. These bands move with the flow and distribute their cumulative precipitation evenly over the mountain upslope. Similar shear-parallel bands also develop in flows where convection is initiated by small-scale topographic noise superimposed onto the main mountain profile, but in this case stronger circulations are also triggered that create stationary rainbands parallel to the low-level flow. This second dominant mode, which is less sensitive to the atmospheric structure and the strength of forcing, is triggered by lee waves that form over small-scale topographic bumps near the upstream edge of the main orographic cloud. Due to their stationarity, these flow-parallel bands can produce locally heavy precipitation amounts.

scholarly journals A Multidimensional and Multiscale Model for Pressure Analysis in a Reservoir-Pipe-Valve System

2018 ◽  
Author(s):  
Feng Jie Zheng ◽  
Fu Zheng Qu ◽  
Xue Guan Song
Keyword(s):  
Pressure Fluctuation ◽  
Large Scale ◽  
Three Dimensional ◽  
Industrial Process ◽  
Multiscale Model ◽  
Computational Time ◽  
Small Scale ◽  
Cfd Model ◽  
Computationally Efficient ◽  
Proposed Model

Reservoir-pipe-valve (RPV) systems are widely used in many industrial process. The pressure in an RPV system plays an important role in the safe operation of the system, especially during the sudden operation such as rapid valve opening/closing. To investigate the pressure especially the pressure fluctuation in an RPV system, a multidimensional and multiscale model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the model, the reservoir is modeled by a zero-dimensional virtual point, the pipe is modeled by a one-dimensional MOC, and the valve is modeled by a three-dimensional CFD model. An interface model is used to connect the multidimensional and multiscale model. Based on the model, a transient simulation of the turbulent flow in an RPV system is conducted, in which not only the pressure fluctuation in the pipe but also the detailed pressure distribution in the valve are obtained. The results show that the proposed model is in good agreement with the full CFD model in both large-scale and small-scale spaces. Moreover, the proposed model is more computationally efficient than the CFD model, which provides a feasibility in the analysis of complex RPV system within an affordable computational time.

scholarly journals A Multidimensional and Multiscale Model for Pressure Analysis in a Reservoir-Pipe-Valve System

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Feng Jie Zheng ◽  
Chao Yong Zong ◽  
William Dempster ◽  
Fu Zheng Qu ◽  
Xue Guan Song
Keyword(s):  
Large Scale ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Multiscale Model ◽  
Computational Time ◽  
Small Scale ◽  
Dimensional System ◽  
Cfd Model ◽  
Computationally Efficient ◽  
Proposed Model

Reservoir-pipe-valve (RPV) systems are widely used in many industrial processes. The pressure in an RPV system plays an important role in the safe operation of the system, especially during the sudden operations such as rapid valve opening or closing. To investigate the pressure response, with particular interest in the pressure fluctuations in an RPV system, a multidimensional and multiscale model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the model, the reservoir is modeled as a zero-dimensional virtual point, the pipe is modeled as a one-dimensional system using the MOC, and the valve is modeled using a three-dimensional CFD model. An interface model is used to connect the multidimensional and multiscale model. Based on the model, a transient simulation of the turbulent flow in an RPV system is conducted in which not only the pressure fluctuation in the pipe but also the detailed pressure distribution in the valve is obtained. The results show that the proposed model is in good agreement when compared with a high fidelity CFD model used to represent both large-scale and small-scale spaces. As expected, the proposed model is significantly more computationally efficient than the CFD model. This demonstrates the feasibility of analyzing complex RPV systems within an affordable computational time.

scholarly journals Application of the Semi-Lagrangian Inherently Conserving and Efficient (SLICE) Transport Method to Divergent Flows on a C Grid

2008 ◽  
Vol 136 (12) ◽  
pp. 4850-4866 ◽  
Author(s):  
Ahmed Mahidjiba ◽  
Abdessamad Qaddouri ◽  
Jean Côté
Keyword(s):  
Total Mass ◽  
Small Scale ◽  
Local Conservation ◽  
Cartesian Coordinates ◽  
Passive Advection ◽  
Global Environmental ◽  
Global Environmental Multiscale ◽  
Transport Method

Abstract Local conservation with the Semi-Lagrangian Inherently Conserving and Efficient (SLICE) transport method with a new trajectory algorithm is studied. Validation results of 1D and 2D passive advection with this new algorithm, which converges twice as fast as the old one, on the Arakawa C grid of a model in Cartesian coordinates are obtained. The effects of numerically computed divergence and trajectories on the results were also investigated. Random small-scale errors due to the divergence, especially with realistic winds, can be observed. The total mass is conserved, however, and is not affected since the results show clearly that SLICE ensures a perfect local conservation. This work represents the first step toward implementation of SLICE in the operational Canadian Global Environmental Multiscale (GEM) model.

scholarly journals Assessment of a NEMO-based hydrodynamic modelling system for the Great Lakes

2012 ◽  
Vol 47 (3-4) ◽  
pp. 198-214 ◽  
Author(s):  
Frederic Dupont ◽  
Padala Chittibabu ◽  
Vincent Fortin ◽  
Yerubandi R. Rao ◽  
Youyu Lu
Keyword(s):  
Great Lakes ◽  
Thermal Structure ◽  
Three Dimensional ◽  
Multiscale Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Central Basin ◽  
Surface Mixed Layer ◽  
Global Environmental ◽  
Modelling System

Environment Canada recently developed a coupled lake–atmosphere–hydrological modelling system for the Laurentian Great Lakes. This modelling system consists of the Canadian Regional Deterministic Prediction System (RDPS), which is based on the Global Environmental Multiscale model (GEM), the MESH (Modélisation Environnementale Surface et Hydrologie) surface and river routing model, and a hydrodynamic model based on the three-dimensional global ocean model Nucleus for European Modelling of the Ocean (NEMO). This paper describes the performance of the NEMO model in the Great Lakes. The model was run from 2004 to 2009 with atmospheric forcing from GEM and river forcing from the MESH modelling system for the Great Lakes region and compared with available observations in selected lakes. The NEMO model is able to produce observed variations of lake levels, ice concentrations, lake surface temperatures, surface currents and vertical thermal structure reasonably well in most of the Great Lakes. However, the model produced a diffused thermocline in the central basin of Lake Erie. The model predicted evaporation is relatively strong in the upper lakes. Preliminary results of the modelling system indicate that the model needs further improvements in atmospheric–lake exchange bulk formulae and surface mixed layer physics.

scholarly journals Retrieval of three-dimensional small-scale structures in upper-tropospheric/lower-stratospheric composition as measured by GLORIA

2015 ◽  
Vol 8 (1) ◽  
pp. 81-95 ◽  
Author(s):  
M. Kaufmann ◽  
J. Blank ◽  
T. Guggenmoser ◽  
J. Ungermann ◽  
A. Engel ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Cross Sections ◽  
Lower Stratosphere ◽  
Three Dimensional ◽  
Small Scale ◽  
Flight Pattern ◽  
Upper Troposphere ◽  
In Situ Data ◽  
Very High Spatial Resolution ◽  
First Results

Abstract. The three-dimensional quantification of small-scale processes in the upper troposphere and lower stratosphere is one of the challenges of current atmospheric research and requires the development of new measurement strategies. This work presents the first results from the newly developed Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) obtained during the ESSenCe (ESa Sounder Campaign) and TACTS/ESMVal (TACTS: Transport and composition in the upper troposphere/lowermost stratosphere, ESMVal: Earth System Model Validation) aircraft campaigns. The focus of this work is on the so-called dynamics-mode data characterized by a medium-spectral and a very-high-spatial resolution. The retrieval strategy for the derivation of two- and three-dimensional constituent fields in the upper troposphere and lower stratosphere is presented. Uncertainties of the main retrieval targets (temperature, O3, HNO3, and CFC-12) and their spatial resolution are discussed. During ESSenCe, high-resolution two-dimensional cross-sections have been obtained. Comparisons to collocated remote-sensing and in situ data indicate a good agreement between the data sets. During TACTS/ESMVal, a tomographic flight pattern to sense an intrusion of stratospheric air deep into the troposphere was performed. It was possible to reconstruct this filament at an unprecedented spatial resolution of better than 500 m vertically and 20 × 20 km horizontally.

scholarly journals Evaluation of GPS Precipitable Water over Canada and the IGS Network

2005 ◽  
Vol 44 (1) ◽  
pp. 153-166 ◽  
Author(s):  
Godelieve Deblonde ◽  
Stephen Macpherson ◽  
Yves Mireault ◽  
Pierre Héroux
Keyword(s):  
Precipitable Water ◽  
Multiscale Model ◽  
Geodetic Survey ◽  
Tropospheric Delay ◽  
Observation Network ◽  
Global Environmental ◽  
The Mean ◽  
The Tropics ◽  
Estimated Error ◽  
Global Environmental Multiscale

Abstract Precipitable water (PW) derived from the GPS zenith tropospheric delay (ZTD) is evaluated (as a first step toward variational data assimilation) through comparison with that of collocated radiosondes (RS_PW), operational analyses, and 6-h forecasts (from the Canadian Global Environmental Multiscale model) of the Canadian Meteorological Centre. Two sources of ZTD data are considered: 1) final ZTD (over Canada), computed by the Geodetic Survey Division (GSD) of Natural Resources Canada, and 2) final ZTD (distributed globally), obtained from the International GPS Service (IGS). The mean GSD GPS–derived PW (GPS_PW) is 14.9 mm (reflecting the relatively cold Canadian climate), whereas that of the IGS dataset is 20.8 mm. Intercomparison statistics [correlation, standard deviation (SD), and bias] between GPS_PW and RS_PW are, respectively, 0.97, 2.04 mm, and 1.35 mm for the GSD data and 0.98, 2.6 mm, and 0.67 mm for the IGS data. Comparisons of GPS_PW with 6-h forecast PW (TRIAL_PW) show slightly lower correlations and a higher SD. The increase in SD is greater for the IGS data, which is not surprising, because in regions such as the Tropics and subtropics, moisture forecasts are of a lower quality and the RS observation network is sparse. From a three-way intercomparison (IGS GPS_PW, RS_PW, and TRIAL_PW) of the SD statistics, it is found that GPS_PW has the lowest estimated PW error (≈1 mm) for PW in the 5–30-mm range. For PW greater than 30 mm, the RS_PW estimated error is ≈2 mm, and that of GPS_PW is ≈2.5 mm. The TRIAL_PW estimated error increases with PW, reaching 5.5 mm in the 40–55-mm PW range. These intercomparison results indicate that GPS_PW should be a useful source of humidity information for NWP applications.

scholarly journals GEM-AQ, an on-line global multiscale chemical weather system: model description and evaluation of gas phase chemistry processes

2007 ◽  
Vol 7 (5) ◽  
pp. 14895-14937 ◽  
Author(s):  
J. W. Kaminski ◽  
L. Neary ◽  
J. Struzewska ◽  
J. C. McConnell ◽  
A. Lupu ◽  
...  
Keyword(s):  
Multiscale Model ◽  
Global Scale ◽  
Tropospheric Chemistry ◽  
Model Description ◽  
Weather System ◽  
Gas Phase Chemistry ◽  
Global Environmental ◽  
On Line ◽  
Phase Chemistry ◽  
Global Environmental Multiscale

Abstract. Tropospheric chemistry and air quality processes were implemented on-line in the Global Environmental Multiscale model. The integrated model, GEM-AQ, has been developed as a platform to investigate chemical weather at scales from global to urban. The model was exercised for five years (2001–2005) to evaluate its ability to simulate seasonal variations and regional distributions of trace gases such as ozone, nitrogen dioxide and carbon monoxide on the global scale. The model results presented are compared with observations from satellites, aircraft measurement campaigns and balloon sondes.

scholarly journals Verification of High-Resolution Medium-Range Precipitation Forecasts from Global Environmental Multiscale Model over China during 2009–2013

Atmosphere ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. 104 ◽  
Author(s):  
Huating Xu ◽  
Zhiyong Wu ◽  
Lifeng Luo ◽  
Hai He
Keyword(s):  
High Resolution ◽  
Multiscale Model ◽  
Global Environmental ◽  
Medium Range ◽  
Global Environmental Multiscale

Crystallization

2015 ◽  
Author(s):  
Roger G. Harrison ◽  
Paul W. Todd ◽  
Scott R. Rudge ◽  
Demetri P. Petrides
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Crystal Form ◽  
Solid Particles ◽  
Dimensional Structure ◽  
Internal Quality ◽  
Small Scale ◽  
X Ray Diffraction ◽  
Production Scale ◽  
Homogeneous Phase

Crystallization is the process of producing crystals from a homogeneous phase. For biochemicals, the homogeneous phase from which crystals are obtained is always a solution. Crystallization is similar to precipitation in that solid particles are obtained from a solution. However, precipitates have poorly defined morphology, while in crystals the constituent molecules are arranged in three-dimensional arrays called space lattices. In comparison to crystallization, precipitation occurs at much higher levels of supersaturation and rates of nucleation but lower solubilities. These and other differences between crystallization and precipitation are highlighted in Table 9.1. Because of these differences and because the theory of crystallization that has been developed is different from that for precipitation, crystallization is considered separately from precipitation. Crystallization is capable of producing bioproducts at very high purity (say, 99.9%) and is considered to be both a polishing step and a purification step. Polishing refers to a process needed to put the bioproduct in its final form for use. For some bioproducts, such as antibiotics, this final form must be crystalline, and sometimes it is even necessary that a specific crystal form be obtained. In some instances, the purification that can be achieved by crystallization is so significant that other more expensive purification steps such as chromatography can be avoided. There are actually two very different applications of crystallization in biotechnology and bioproduct engineering: crystallization for polishing and purification, and crystallization for crystallography. In the latter case, the goal is a small number of crystals with good size (0.2–0.9 mm) and internal quality. Although it has become common to crystallize proteins for characterization of their three-dimensional structure by x-ray diffraction, this is performed only at small scale in the laboratory, and the knowledge about how to crystallize proteins at large scale in a production process is less developed. However, many antibiotics and other small biomolecules are routinely crystallized in production scale processes. This chapter is oriented toward the use of crystallization in processes that can be scaled up.

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