scholarly journals IL-GLOBO (1.0) – development and verification of the moist convection module

2016 ◽  
Vol 9 (2) ◽  
pp. 789-797 ◽  
Author(s):  
Daniele Rossi ◽  
Alberto Maurizi ◽  
Maurizio Fantini
Keyword(s):  
General Circulation ◽  
Transport Model ◽  
Transition Probability ◽  
Circulation Model ◽  
Transition Probability Matrix ◽  
Moist Convection ◽  
Tropical Area ◽  
The Tropics ◽  
The Impact ◽  
Very High

Abstract. The development and verification of the convective module of IL-GLOBO, a Lagrangian transport model coupled online with the Eulerian general circulation model GLOBO, is described. The online-coupling promotes the full consistency between the Eulerian and the Lagrangian components of the model. The Lagrangian convective scheme is based on the Kain–Fritsch convective parametrization used in GLOBO. A transition probability matrix is computed using the fluxes provided by the Eulerian KF parametrization. Then, the convective redistribution of Lagrangian particles is implemented via a Monte Carlo scheme. The formal derivation is described in details and, consistently with the Eulerian module, includes the environmental flux in the transition probability matrix to avoid splitting of the convection and subsidence processes. Consistency of the Lagrangian implementation with its Eulerian counterpart is verified by computing environment fluxes from the transition probability matrix and comparing them to those computed by the Eulerian module. Assessment of the impact of the module is made for different latitudinal belts, showing that the major impact is found in the Tropics, as expected. Concerning vertical distribution, the major impact is observed in the boundary layer at every latitude, while in the tropical area, the influence extends to very high levels.

scholarly journals IL-GLOBO (1.0) – development and verification of the moist convection module

2015 ◽  
Vol 8 (9) ◽  
pp. 8239-8261
Author(s):  
D. Rossi ◽  
A. Maurizi ◽  
M. Fantini
Keyword(s):  
General Circulation ◽  
Transport Model ◽  
Transition Probability ◽  
Circulation Model ◽  
Transition Probability Matrix ◽  
Moist Convection ◽  
Tropical Area ◽  
The Tropics ◽  
The Impact ◽  
Very High

Abstract. The development and verification of the convective module of IL-GLOBO, a Lagrangian transport model coupled online with the Eulerian general circulation model GLOBO, is described. The online-coupling promotes the full consistency between the Eulerian and the Lagrangian components of the model. The Lagrangian convective scheme is derived based on the Kain–Fritsch convective parameterisation used in GLOBO. A transition probability matrix is computed using the fluxes provided by the Eulerian KF parameterisation. Then, the convection redistribution of Lagrangian particles is implemented via a Monte Carlo scheme. The formal derivation is described in details and, consistently with the Eulerian module, includes the environmental flux in the transition probability matrix to avoid splitting of the convection and subsidence processes. Consistency of the Lagrangian implementation with its Eulerian counterpart is verified by computing environment fluxes from the transition probability matrix and comparing them to those computed by the Eulerian module. Assessment of the impact of the module is made for different latitudinal belts, showing that the major impact is found in the tropics, as expected. Concerning vertical distribution, the major impact is observed in the boundary layer at every latitude, while in the tropical area, the influence extends to very high levels.

scholarly journals Simulation of Atmospheric Circulation over Tahiti and of Local Effects on the Transport of 210Pb

2009 ◽  
Vol 137 (6) ◽  
pp. 1863-1880 ◽  
Author(s):  
P. Heinrich ◽  
X. Blanchard
Keyword(s):  
Atmospheric Circulation ◽  
General Circulation ◽  
Transport Model ◽  
Mesoscale Model ◽  
Natural Radionuclide ◽  
Circulation Model ◽  
Spatial And Temporal Variability ◽  
Local Circulation ◽  
Meteorological Model ◽  
The Impact

Abstract Atmospheric transport of the natural radionuclide 210Pb is simulated by a general circulation model (GCM) and calculated surface concentrations are compared with those recorded at the Tahiti station on a daily scale. Numerical results for 2006 show the underestimation of concentrations for most recorded peaks. The purpose of this paper is to explain the observed discrepancies, to evaluate the GCM physical parameterizations, and to determine by numerical means the concentrations at Tahiti for a pollutant circulating across the South Pacific Ocean. Three meteorological situations in 2006 are further analyzed. Circulation over Tahiti for these periods is simulated by a mesoscale meteorological model using four nested grids with resolutions ranging from 27 to 1 km. The calculated wind fields are validated by those observed at two stations on the northwest coast of Tahiti, which is exposed both to topography-induced vortices and to thermally driven local breezes. Atmospheric dispersion of an offshore plume is then calculated by a particle Lagrangian transport model, driven by the mesoscale model at 1- and 81-km resolutions, representing local and global circulations, respectively. Simulations at 1-km resolution show the complex atmospheric circulation over Tahiti, which results in a large spatial and temporal variability of 210Pb surface concentrations on an hourly scale. The impact of local circulation is, however, limited when daily averaged concentrations at the station are considered. Under the studied regimes, transport simulations at the two resolutions lead to similar daily averaged concentrations. The deficiencies of the GCM in simulating daily averaged 210Pb concentrations could be attributable to the deep convection parameterization.

scholarly journals The Role of Eddies in Driving the Tropospheric Response to Stratospheric Heating Perturbations

2009 ◽  
Vol 66 (5) ◽  
pp. 1347-1365 ◽  
Author(s):  
Isla R. Simpson ◽  
Michael Blackburn ◽  
Joanna D. Haigh
Keyword(s):  
General Circulation ◽  
Storm Track ◽  
Circulation Model ◽  
Index Of Refraction ◽  
Symmetric Model ◽  
Similar Response ◽  
Model Response ◽  
Tropospheric Circulation ◽  
The Tropics ◽  
The Impact

Abstract A simplified general circulation model has been used to investigate the chain of causality whereby changes in tropospheric circulation and temperature are produced in response to stratospheric heating perturbations. Spinup ensemble experiments have been performed to examine the evolution of the tropospheric circulation in response to such perturbations. The primary aim of these experiments is to investigate the possible mechanisms whereby a tropospheric response to changing solar activity over the 11-yr solar cycle could be produced in response to heating of the equatorial lower stratosphere. This study therefore focuses on a stratospheric heating perturbation in which the heating is largest in the tropics. For comparison, experiments are also performed in which the stratosphere is heated uniformly at all latitudes and in which it is heated preferentially in the polar region. Thus, the mechanisms discussed have a wider relevance for the impact of stratospheric perturbations on the troposphere. The results demonstrate the importance of changing eddy momentum fluxes in driving the tropospheric response. This is confirmed by the lack of a similar response in a zonally symmetric model with fixed eddy forcing. Furthermore, it is apparent that feedback between the tropospheric eddy fluxes and tropospheric circulation changes is required to produce the full model response. The quasigeostrophic index of refraction is used to diagnose the cause of the changes in eddy behavior. It is demonstrated that the latitudinal extent of stratospheric heating is important in determining the direction of displacement of the tropospheric jet and storm track.

Response of the Atmosphere to Orographic Forcings: Insight from Idealised Simulations

2021 ◽  
Author(s):  
Kamal Tewari ◽  
Saroj K. Mishra ◽  
Anupam Dewan ◽  
Abhishek Anand ◽  
In-Sik Kang
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Separation Distance ◽  
Precipitation Pattern ◽  
Stationary Waves ◽  
Flux Transport ◽  
Tropical Mountains ◽  
The Tropics ◽  
The Impact ◽  
Poleward Flux

AbstractEarth’s orography profoundly influences its climate and is a major reason behind the zonally asymmetric features observed in the atmospheric circulation. The response of the atmosphere to orographic forcing, when idealized aqua mountains are placed individually and in pairs (180° apart) at different latitudes, is investigated in the present study using a simplified general circulation model. The investigation reveals that the atmospheric response to orography is dependent on its latitudinal position: orographically triggered stationary waves in the mid-latitudes are most energetic compared to the waves generated due to anomalous divergence in the tropics. The impact on precipitation is confined to the latitude of the orography when it is placed near the tropics, but when it is situated at higher latitudes, it also has a significant remote impact on the tropics. In general, the tropical mountains block the easterly flow, resulting in a weakening of the Hadley cells and a local reduction in the total poleward flux transport by the stationary eddies. On the other hand, the mid-latitudinal orography triggers planetary-scale Rossby waves and enhances the poleward flux transport by stationary eddies. The twin mountains experiments, which are performed by placing orography in pairs at different latitudes, show that the energy fluxes, stationary wave, and precipitation pattern are not merely the linear additive sum of individual orographic responses at these latitudes. The non-linearity in a diagnostic sense is a product interaction of flow between the two mountains, which depends on the background flow, the separation distance between mountains, and wind shear worldwide.

scholarly journals Observationally derived transport diagnostics for the lowermost stratosphere and their application to the GMI chemistry and transport model

2007 ◽  
Vol 7 (9) ◽  
pp. 2435-2445 ◽  
Author(s):  
S. E. Strahan ◽  
B. N. Duncan ◽  
P. Hoor
Keyword(s):  
General Circulation ◽  
Transport Model ◽  
Lower Layer ◽  
Potential Temperature ◽  
Circulation Model ◽  
Chemical Mechanism ◽  
Data Sets ◽  
Extratropical Tropopause ◽  
Stratospheric Composition ◽  
The Impact

Abstract. Transport from the surface to the lowermost stratosphere (LMS) can occur on timescales of a few months or less, making it possible for short-lived tropospheric pollutants to influence stratospheric composition and chemistry. Models used to study this influence must demonstrate the credibility of their chemistry and transport in the upper troposphere and lower stratosphere (UT/LS). Data sets from satellite and aircraft instruments measuring CO, O3, N2O, and CO2 in the UT/LS are used to create a suite of diagnostics for the seasonally-varying transport into and within the lowermost stratosphere, and of the coupling between the troposphere and stratosphere in the extratropics. The diagnostics are used to evaluate a version of the Global Modeling Initiative (GMI) Chemistry and Transport Model (CTM) that uses a combined tropospheric and stratospheric chemical mechanism and meteorological fields from the GEOS-4 general circulation model. The diagnostics derived from N2O and O3 show that the model lowermost stratosphere has realistic input from the overlying high latitude stratosphere in all seasons. Diagnostics for the LMS show two distinct layers. The upper layer begins ~30 K potential temperature above the tropopause and has a strong annual cycle in its composition. The lower layer is a mixed region ~30 K thick near the tropopause that shows no clear seasonal variation in the degree of tropospheric coupling. Diagnostics applied to the GMI CTM show credible seasonally-varying transport in the LMS and a tropopause layer that is realistically coupled to the UT in all seasons. The vertical resolution of the GMI CTM in the UT/LS, ~1 km, is sufficient to realistically represent the extratropical tropopause layer. This study demonstrates that the GMI CTM has the transport credibility required to study the impact of tropospheric emissions on the stratosphere.

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 On the uses of a new linear scheme for stratospheric methane in global models: water source, transport tracer and radiative forcing

2012 ◽  
Vol 12 (1) ◽  
pp. 479-523 ◽  
Author(s):  
B. M. Monge-Sanz ◽  
M. P. Chipperfield ◽  
A. Untch ◽  
J.-J. Morcrette ◽  
A. Rap ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
General Circulation ◽  
Transport Model ◽  
Circulation Model ◽  
Water Source ◽  
Reanalysis Data ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Ecmwf Model ◽  
The Impact

Abstract. A new linear parameterisation for stratospheric methane (CoMeCAT) has been developed and tested. The scheme is derived from a 3-D full chemistry transport model (CTM) and tested within the same chemistry model itself, as well as in an independent general circulation model (GCM). The new CH4/H2O scheme is suitable for any global model and here is shown to provide realistic profiles in the 3-D TOMCAT/SLIMCAT CTM and in the ECMWF (European Centre for Medium-Range Weather Forecasts) GCM. Simulation results from the new stratospheric scheme are in good agreement with the full-chemistry CTM CH4 field and with observations from the Halogen Occultation Experiment (HALOE). The CH4 scheme has also been used to derive a source for stratospheric water. Stratospheric water increments obtained in this way within the CTM produce vertical and latitudinal H2O variation in fair agreement with satellite observations. Stratospheric H2O distributions in the ECMWF GCM present realistic overall features although concentrations are lower than in the CTM run (up to 0.5 ppmv lower above 10 hPa). The potential of the new CoMeCAT scheme for evaluating long-term transport within the ECMWF model is exploited to assess the impacts of nudging the free running GCM to ERA-40 and ERA-Interim reanalyses. In this case, the nudged GCM shows similar transport patterns to the CTM forced by the corresponding reanalysis data, ERA-Interim producing better results than ERA-40. The impact that the new methane description has in the GCM radiation scheme is also explored. Compared to the default CH4 climatology used by the ECMWF model, CoMeCAT produces up to 2 K cooling in the tropical lower stratosphere. The effect of using the CoMeCAT scheme for radiative forcing (RF) calculations has been investigated using the off-line Edwards-Slingo (E-S) radiative transfer model. Compared to the use of a tropospheric global 3-D CH4 value, the CoMeCAT distributions produce an overall decrease in the annual mean net RF, with the largest decrease found over the Southern Hemisphere high latitudes. The effect of the new CH4 stratospheric distribution on these RF calculations is of up to 30 mW m−2, i.e. the same order of magnitude, and opposite sign, as the inclusion of aircraft contrails formation in the radiative model.

scholarly journals Effects of business-as-usual anthropogenic emissions on air quality

2012 ◽  
Vol 12 (15) ◽  
pp. 6915-6937 ◽  
Author(s):  
A. Pozzer ◽  
P. Zimmermann ◽  
U.M. Doering ◽  
J. van Aardenne ◽  
H. Tost ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
East Asia ◽  
South Asia ◽  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Business As Usual ◽  
The Impact ◽  
Very High

Abstract. The atmospheric chemistry general circulation model EMAC has been used to estimate the impact of anthropogenic emission changes on global and regional air quality in recent and future years (2005, 2010, 2025 and 2050). The emission scenario assumes that population and economic growth largely determine energy and food consumption and consequent pollution sources with the current technologies ("business as usual"). This scenario is chosen to show the effects of not implementing legislation to prevent additional climate change and growing air pollution, other than what is in place for the base year 2005, representing a pessimistic (but plausible) future. By comparing with recent observations, it is shown that the model reproduces the main features of regional air pollution distributions though with some imprecisions inherent to the coarse horizontal resolution (~100 km) and simplified bottom-up emission input. To identify possible future hot spots of poor air quality, a multi pollutant index (MPI), suited for global model output, has been applied. It appears that East and South Asia and the Middle East represent such hotspots due to very high pollutant concentrations, while a general increase of MPIs is observed in all populated regions in the Northern Hemisphere. In East Asia a range of pollutant gases and fine particulate matter (PM2.5) is projected to reach very high levels from 2005 onward, while in South Asia air pollution, including ozone, will grow rapidly towards the middle of the century. Around the Persian Gulf, where natural PM2.5 concentrations are already high (desert dust), ozone levels are expected to increase strongly. The population weighted MPI (PW-MPI), which combines demographic and pollutant concentration projections, shows that a rapidly increasing number of people worldwide will experience reduced air quality during the first half of the 21st century. Following this business as usual scenario, it is projected that air quality for the global average citizen in 2050 would be almost comparable to that for the average citizen in East Asia in the year 2005, which underscores the need to pursue emission reductions.

scholarly journals Observationally derived transport diagnostics for the lowermost stratosphere and their application to the GMI chemistry and transport model

2007 ◽  
Vol 7 (1) ◽  
pp. 1449-1477 ◽  
Author(s):  
S. E. Strahan ◽  
B. N. Duncan ◽  
P. Hoor
Keyword(s):  
General Circulation ◽  
Transport Model ◽  
Lower Layer ◽  
Circulation Model ◽  
Chemical Mechanism ◽  
Data Sets ◽  
Global Modeling ◽  
Upper Troposphere ◽  
Stratospheric Composition ◽  
The Impact

Abstract. Transport from the surface to the lowermost stratosphere can occur on timescales of a few months or less, making it possible for short-lived tropospheric pollutants to influence stratospheric composition and chemistry. Models used to study this influence must demonstrate the credibility of their chemistry and transport in the upper troposphere and lower stratosphere (UT/LS). Data sets from satellite and aircraft instruments measuring CO, O3, N2O, and CO2 in the UT/LS are used to create a suite of diagnostics of the seasonally-varying transport into and within the lowermost stratosphere, and of the coupling between the troposphere and stratosphere in the extratropics. The diagnostics are used to evaluate a version of the Global Modeling Initiative (GMI) Chemistry and Transport Model that uses a combined tropospheric and stratospheric chemical mechanism and meteorological fields from the GEOS-4 general circulation model. The diagnostics derived from N2O and O3 show that the model lowermost stratosphere (LMS) has realistic input from the overlying high latitude stratosphere in all seasons. Diagnostics for the LMS show two distinct layers. The upper layer (~350 K–380 K) has a strong annual cycle in its composition, while the lower layer, just above the tropopause, shows no seasonal variation in the degree of tropospheric coupling or composition. The GMI CTM agrees closely with the observations in both layers and is realistically coupled to the UT in all seasons. This study demonstrates the credibility of the GMI CTM for the study of the impact of tropospheric emissions on the stratosphere.

scholarly journals Effects of business-as-usual anthropogenic emissions on air quality

2012 ◽  
Vol 12 (4) ◽  
pp. 8617-8676
Author(s):  
A. Pozzer ◽  
P. Zimmermann ◽  
U.M. Doering ◽  
J. van Aardenne ◽  
H. Tost ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
East Asia ◽  
South Asia ◽  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Business As Usual ◽  
The Impact ◽  
Very High

Abstract. The atmospheric chemistry general circulation model EMAC has been used to estimate the impact of anthropogenic emission changes on global and regional air quality in recent and future years (2005, 2010, 2025 and 2050). The emission scenario assumes that population and economic growth largely determine energy and food consumption and consequent pollution sources with the current technologies ("business as usual"). This scenario is chosen to show the effects of not implementing legislation to prevent additional climate change and growing air pollution, other than what is in place for the base year 2005, representing a pessimistic (but feasible) future. By comparing with recent observations, it is shown that the model reproduces the main features of regional air pollution distributions though with some imprecisions inherent to the coarse horizontal resolution (~100 km) and simplified bottom-up emission input. To identify possible future hot spots of poor air quality, a multi pollutant index (MPI), suited for global model output, has been applied. It appears that East and South Asia and the Middle East represent such hotspots due to very high pollutant concentrations, although a general increase of MPIs is observed in all populated regions in the Northern Hemisphere. In East Asia a range of pollutant gases and fine particulate matter (PM2.5) is projected to reach very high levels from 2005 onward, while in South Asia air pollution, including ozone, will grow rapidly towards the middle of the century. Around the Arabian Gulf, where natural PM2.5 concentrations are already high (desert dust), ozone levels are expected to increase strongly. The per capita MPI (PCMPI), which combines demographic and pollutants concentrations projections, shows that a rapidly increasing number of people worldwide will experience reduced air quality during the first half of the 21st century. Following the business as usual scenario, it is projected that air quality for the global average citizen in 2050 would be almost comparable to that for the average citizen in the East Asia in the year 2005, which underscores the need to pursue emission reductions.

Sign in / Sign up

Export Citation Format

Share Document