scholarly journals USDOE - Final report 2000/2001 [Global Environmental Multiscale (GEM) global variable resolution model]

2001 ◽  
Author(s):  
Jean Cote
Keyword(s):  
Final Report ◽  
Variable Resolution ◽  
Global Environmental ◽  
Resolution Model ◽  
Global Variable ◽  
Global Environmental Multiscale

scholarly journals The Australian bushfires of February 2009: MIPAS observations and GEM-AQ model results

2013 ◽  
Vol 13 (3) ◽  
pp. 1637-1658 ◽  
Author(s):  
N. Glatthor ◽  
M. Höpfner ◽  
K. Semeniuk ◽  
A. Lupu ◽  
P. I. Palmer ◽  
...  
Keyword(s):  
New Zealand ◽  
Michelson Interferometer ◽  
Combustion Products ◽  
Global Environmental ◽  
Resolution Model ◽  
The Indian Ocean ◽  
High Resolution Model ◽  
Global Environmental Multiscale ◽  
Central South ◽  
Emission Ratios

Abstract. Starting on 7 February 2009, southeast Australia was devastated by large bushfires, which burned an area of about 3000 km2 on this day alone. This event was extraordinary, because a large number of combustion products were transported into the uppermost troposphere and lower stratosphere within a few days. Various biomass burning products released by the fire were observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the Envisat satellite. We tracked the plume using MIPAS C2H2, HCN and HCOOH single-scan measurements on a day-to-day basis. The measurements were compared with a high-resolution model run of the Global Environmental Multiscale Air Quality (GEM-AQ) model. Generally there is good agreement between the spatial distribution of measured and modelled pollutants. Both MIPAS and GEM-AQ show a fast southeastward transport of the pollutants to New Zealand within one day. During the following 3–4 days, the plume remained northeastward of New Zealand and was located at altitudes of 15 to 18 km. Thereafter its lower part was transported eastward, followed by westward transport of its upper part. On 17 February the eastern part had reached southern South America and on 20 February the central South Atlantic. On the latter day a second relic of the plume was observed moving eastward above the South Pacific. Between 20 February and the first week of March, the upper part of the plume was transported westward over Australia and the Indian Ocean towards southern Africa. First evidence for entry of the pollutants into the stratosphere was found in MIPAS data of 11 February, followed by larger amounts on 17 February and the days thereafter. From MIPAS data, C2H2/HCN and HCOOH/HCN enhancement ratios of 0.76 and 2.16 were calculated for the first days after the outbreak of the fires, which are considerably higher than the emission ratios assumed for the model run and at the upper end of values found in literature. From the temporal decrease of the enhancement ratios, mean lifetimes of 16–20 days and of 8–9 days were calculated for measured C2H2 and HCOOH. The respective lifetimes calculated from the model data are 18 and 12 days.

Very high-resolution climate simulation over Fiji using a global variable-resolution model

2007 ◽  
Vol 30 (2-3) ◽  
pp. 293-305 ◽  
Author(s):  
Murari Lal ◽  
John L. McGregor ◽  
Kim C. Nguyen
Keyword(s):  
High Resolution ◽  
Climate Simulation ◽  
Variable Resolution ◽  
Resolution Model ◽  
Global Variable ◽  
Very High

scholarly journals The Australian bush fires of February 2009: MIPAS observations and GEM-AQ model results

2012 ◽  
Vol 12 (6) ◽  
pp. 15009-15048
Author(s):  
N. Glatthor ◽  
M. Höpfner ◽  
K. Semeniuk ◽  
A. Lupu ◽  
P. I. Palmer ◽  
...  
Keyword(s):  
New Zealand ◽  
South African ◽  
Michelson Interferometer ◽  
Combustion Products ◽  
Global Environmental ◽  
Resolution Model ◽  
The Indian Ocean ◽  
High Resolution Model ◽  
Global Environmental Multiscale ◽  
Good Agreement

Abstract. On 7 February 2009, and the following days Southeast Australia was devastated by large bush fires, which burned an area of about 3000 km2. This event was extraordinary, because a large number of combustion products was transported into the uppermost troposphere and lower stratosphere within a few days. Various biomass burning products released by the fire were observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the ENVISAT satellite. We track the plume using MIPAS C2H2, HCN and HCOOH single-scan measurements on a day-to-day basis. The measurements are compared with a high-resolution model run of the Global Environmental Multiscale-Air Quality (GEM-AQ) model. Generally there is very good agreement between the spatial distribution of measured and modelled pollutants during the first two weeks after the outbreak of the fire even over intercontinental distances. Both MIPAS and GEM-AQ show a fast south-eastward transport of the pollutants to New Zealand within one day. During the following 3–4 days the plume was located north and eastward of New Zealand and centered at altitudes of 15 to 18 km. Thereafter its eastern part was transported eastward at altitudes of 15–16 km, followed by westward transport of its western part at somewhat higher altitudes. On 17 February the eastern part had reached Southern South America and on 20 February the South African west coast. On the latter day a second relic of the plume was observed moving eastward above the Southern Pacific, whereas the westward transported pollutants were located above Australia at altitudes of 18–20 km. First evidence for entry of the pollutants into the stratosphere was found in MIPAS data of 11 February, followed by larger amounts on 17 February and the days thereafter. Between 20 February and the first week of March the stratospheric pollutants above Australia were transported further westward over the Indian Ocean towards Southern Africa.

scholarly journals Simulating Global and North American Climate Using the Global Environmental Multiscale Model with a Variable-Resolution Modeling Approach

2010 ◽  
Vol 138 (10) ◽  
pp. 3967-3987 ◽  
Author(s):  
Marko Markovic ◽  
Hai Lin ◽  
Katja Winger
Keyword(s):  
North America ◽  
Indian Ocean ◽  
Interannual Variability ◽  
Tropical Pacific ◽  
Eastern Indian Ocean ◽  
Variable Resolution ◽  
Modeling Approach ◽  
Global Environmental ◽  
Global Environmental Multiscale ◽  
The Tropical Pacific

Abstract Results from two simulations using the Global Environmental Multiscale (GEM) model in a variable-resolution modeling approach are evaluated. Simulations with a highly resolved domain positioned over North America and over the tropical Pacific–eastern Indian Ocean are assessed against the GEM uniform grid control run, 40-yr ECMWF Re-Analysis (ERA-40), and available observations in terms of regional and global climate and interannual variability. It is found that the variable-resolution configurations realistically simulate global and regional climate over North America with seasonal means and variability generally closer to ERA-40 or observations than the control run. Systematic errors of the control run are still present within the variable-resolution simulations but alleviated to some extent over their respective highly resolved domains. Additionally, there is some evidence of performance deterioration due to the increased resolution. There is little evidence that an increased resolution over the tropical Pacific–eastern Indian Ocean, with better-resolved local processes (e.g., convection and equatorial waves), has a significant impact on the extratropical time mean fields. However, in terms of simulating the Northern Hemisphere atmospheric flow anomaly associated with the dominant mode of sea surface temperature interannual variability in the equatorial eastern Pacific (i.e., El Niño), both stretched configurations have more realistic teleconnection patterns than the control run.

Convection‐permitting hindcasting of diurnal variation of Mei‐yu rainfall over East China with a global variable‐resolution model

2021 ◽  
Author(s):  
Mingyue Xu ◽  
Chun Zhao ◽  
Jun Gu ◽  
Jiawang Feng ◽  
Samson Hagos ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
East China ◽  
Variable Resolution ◽  
Resolution Model ◽  
Global Variable

Influences of Large-Scale Flow Variations on the Track Evolution of Typhoons Morakot (2009) and Megi (2010): Simulations with a Global Variable-Resolution Model

2017 ◽  
Vol 145 (5) ◽  
pp. 1691-1716 ◽  
Author(s):  
Ching-Yuang Huang ◽  
You Zhang ◽  
William C. Skamarock ◽  
Li-Huan Hsu
Keyword(s):  
Large Scale ◽  
Extreme Rainfall ◽  
Mountain Range ◽  
Variable Resolution ◽  
The North ◽  
Positive Vorticity ◽  
Resolution Model ◽  
Global Variable ◽  
Southern Taiwan ◽  
Large Scale Flow

Abstract Influences of large-scale flow variations on the track evolution of two typhoons, moderate Morakot (2009) and superintense Megi (2010), are investigated using the global variable-resolution model MPAS with a higher-resolution region of 15 km for the simulated typhoons. For Morakot, the associated track and extreme rainfall over southern Taiwan captured by MPAS compared well with the regional WRF simulations. To isolate the influences of various large-scale flows, three modes are filtered out from global reanalysis: the synoptic-scale mode, quasi-biweekly oscillation (QBW) mode, and the Madden–Julian oscillation (MJO) mode. In the absence of QBW or MJO, the simulated Morakot moves westward across Taiwan without the observed north turn after landfall. When the intensity of the MJO mode is increased by 50% in the experiment (MJO+50%), a much earlier northward turn is induced. The simulated Morakot under the observed MJO lies in between MJO+50% and MJO−50% results. The MJO variations also show similar impacts on the track evolution of Typhoon Megi. The wavenumber-1 decompositions of vorticity budget terms are shown to highlight important contributions to the vorticity tendency and typhoon translation with and without the MJO. The northward turn of both typhoons in the presence of the MJO is mainly in response to positive horizontal vorticity advection to the north of the typhoon center. However, vorticity tilting is relatively more important for Morakot due to its slantwise structure. Furthermore, positive vorticity stretching and vertical advection are significant in the vicinity of southern Taiwan due to the effects of the Central Mountain Range and tend to retard the departing Morakot.

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 Staggered Vertical Discretization of the Canadian Environmental Multiscale (GEM) Model Using a Coordinate of the Log-Hydrostatic-Pressure Type

2014 ◽  
Vol 142 (3) ◽  
pp. 1183-1196 ◽  
Author(s):  
Claude Girard ◽  
André Plante ◽  
Michel Desgagné ◽  
Ron McTaggart-Cowan ◽  
Jean Côté ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Solution Method ◽  
Time Integration ◽  
Atmospheric Model ◽  
Integration Scheme ◽  
Limited Area ◽  
Vertical Coordinate ◽  
Global Environmental ◽  
Time Integration Scheme ◽  
Global Environmental Multiscale

Abstract The Global Environmental Multiscale (GEM) model is the Canadian atmospheric model used for meteorological forecasting at all scales. A limited-area version now also exists. It is a gridpoint model with an implicit semi-Lagrangian iterative space–time integration scheme. In the “horizontal,” the equations are written in spherical coordinates with the traditional shallow atmosphere approximations and are discretized on an Arakawa C grid. In the “vertical,” the equations were originally defined using a hydrostatic-pressure coordinate and discretized on a regular (unstaggered) grid, a configuration found to be particularly susceptible to noise. Among the possible alternatives, the Charney–Phillips grid, with its unique characteristics, and, as the vertical coordinate, log-hydrostatic pressure are adopted. In this paper, an attempt is made to justify these two choices on theoretical grounds. The resulting equations and their vertical discretization are described and the solution method of what is forming the new dynamical core of GEM is presented, focusing on these two aspects.

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