scholarly journals The Brazilian Global Atmospheric Model (BAM): Performance for Tropical Rainfall Forecasting and Sensitivity to Convective Scheme and Horizontal Resolution

2016 ◽  
Vol 31 (5) ◽  
pp. 1547-1572 ◽  
Author(s):  
Silvio N. Figueroa ◽  
José P. Bonatti ◽  
Paulo Y. Kubota ◽  
Georg A. Grell ◽  
Hugh Morrison ◽  
...  
Keyword(s):  
South America ◽  
Weather Prediction ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Southeastern Brazil ◽  
Rainfall Forecasting ◽  
Dynamical Core ◽  
Tropical Rainfall ◽  
Global Atmospheric Model ◽  
Convective Scheme

Abstract This article describes the main features of the Brazilian Global Atmospheric Model (BAM), analyses of its performance for tropical rainfall forecasting, and its sensitivity to convective scheme and horizontal resolution. BAM is the new global atmospheric model of the Center for Weather Forecasting and Climate Research [Centro de Previsão de Tempo e Estudos Climáticos (CPTEC)], which includes a new dynamical core and state-of-the-art parameterization schemes. BAM’s dynamical core incorporates a monotonic two-time-level semi-Lagrangian scheme, which is carried out completely on the model grid for the tridimensional transport of moisture, microphysical prognostic variables, and tracers. The performance of the quantitative precipitation forecasts (QPFs) from two convective schemes, the Grell–Dévényi (GD) scheme and its modified version (GDM), and two different horizontal resolutions are evaluated against the daily TRMM Multisatellite Precipitation Analysis over different tropical regions. Three main results are 1) the QPF skill was improved substantially with GDM in comparison to GD; 2) the increase in the horizontal resolution without any ad hoc tuning improves the variance of precipitation over continents with complex orography, such as Africa and South America, whereas over oceans there are no significant differences; and 3) the systematic errors (dry or wet biases) remain virtually unchanged for 5-day forecasts. Despite improvements in the tropical precipitation forecasts, especially over southeastern Brazil, dry biases over the Amazon and La Plata remain in BAM. Improving the precipitation forecasts over these regions remains a challenge for the future development of the model to be used not only for numerical weather prediction over South America but also for global climate simulations.

scholarly journals ACOPLAMENTO BRAMS-WW3 PARA PREVISÃO DE ONDAS OCEÂNICAS

2016 ◽  
Vol 38 ◽  
pp. 401
Author(s):  
Renata Sampaio da Rocha Ruiz ◽  
Rosio Del Pilar Camayo Maita ◽  
Haroldo Fraga de Campos Velho ◽  
Saulo Freitas ◽  
Valdir Innocentini
Keyword(s):  
South America ◽  
Wind Field ◽  
Weather Prediction ◽  
Circulation Model ◽  
Ocean Waves ◽  
Horizontal Resolution ◽  
Southeastern Brazil ◽  
Meteorological Model ◽  
Wavewatch Iii ◽  
Global Atmospheric Circulation

A version of the coupled ocean waves WaveWatch III (WW3) model with mesoscale meteorological model BRAMS is presented. The WW3 is a model for waves forecasting. The BRAMS model is used for numerical weather prediction over South America, with horizontal resolution of 5 km. Both models are executed operationally by the CPTEC-INPE. The boundary conditions for the BRAMS model are provided by the global atmospheric circulation model of the CPTEC-INPE. The simulation with BRAMS for14/Oct/2014 generated a wind field with better agreement with the observations (satellite Metop-A, ASCAT sensor) to the coast of southeastern Brazil) than the field wind generated by the SFM model. The simulation with wind field generated by BRAMS produces higher waves than ones predicted with GFS wind field.

scholarly journals Evaluation of the CAMS global atmospheric trace gas reanalysis 2003–2016 using aircraft campaign observations

2020 ◽  
Vol 20 (7) ◽  
pp. 4493-4521 ◽  
Author(s):  
Yuting Wang ◽  
Yong-Feng Ma ◽  
Henk Eskes ◽  
Antje Inness ◽  
Johannes Flemming ◽  
...  
Keyword(s):  
Chemical Species ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Trace Gas ◽  
Weather Forecasts ◽  
Global Atmospheric Model ◽  
Reactive Gases ◽  
Monitoring Service ◽  
Atmospheric Trace Gas ◽  
Atmospheric Concentrations

Abstract. The Copernicus Atmosphere Monitoring Service (CAMS) operated by the European Centre for Medium-Range Weather Forecasts (ECMWF) has produced a global reanalysis of aerosol and reactive gases (called CAMSRA) for the period 2003–2016. Space observations of ozone, carbon monoxide, NO2 and aerosol optical depth are assimilated by a 4D-Var method in the 60-layer ECMWF global atmospheric model, which for the reanalysis is operated at a horizontal resolution of about 80 km. As a contribution to the evaluation of the reanalysis, we compare atmospheric concentrations of different reactive species provided by the CAMS reanalysis with independent observational data gathered by airborne instrumentation during the field campaigns INTEX-A, INTEX-B, NEAQS-ITCT, ITOP, AMMA, ARCTAS, VOCALS, YAK-AEROSIB, HIPPO and KORUS-AQ. We show that the reanalysis rather successfully reproduces the observed concentrations of chemical species that are assimilated in the system, including O3 and CO with biases generally less than 20 %, but generally underestimates the concentrations of the primary hydrocarbons and secondary organic species. In some cases, large discrepancies also exist for fast-reacting radicals such as OH and HO2.

Surfex : une plateforme pour simuler les flux des surfaces océaniques et continentales

2020 ◽  
pp. 082
Author(s):  
Patrick Le Moigne ◽  
Marie Minvielle
Keyword(s):  
Weather Prediction ◽  
Lower Boundary ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Atmospheric Models ◽  
Physical Processes ◽  
Surface Type ◽  
Lower Boundary Condition ◽  
Continuous Increase ◽  
The Earth

Dans les modèles atmosphériques de prévision numérique du temps et de climat, la surface constitue la condition à la limite inférieure. La grande variété des paysages présents sur l'ensemble du globe et les spécificités de chacun des types de surface rendent complexe sa description dans les modèles. Par ailleurs, l'augmentation constante de la résolution horizontale des modèles nécessite une description fine des surfaces ainsi que des processus mis en jeu lorsqu'atmosphère et surface interagissent. Cet article décrit la plateforme de modélisation Surfex, en particulier comment la grande variété des types de surface est prise en compte, quelles sont les principales paramétrisations physiques et enfin comment est réalisé le couplage à un modèle atmosphérique. Surface is the lower boundary condition of numerical weather prediction and climate atmospheric models. Its representation in models is complicated by the large diversity in landscapes over the Earth, and the specificities of each surface type. In addition, the continuous increase in model horizontal resolution requires an accurate description of surfaces as well as the processes involved when surface and atmosphere are coupled. This article describes the Surfex modelling platform, particularly how the large amount of surface types are accounted for, which are the main physical processes represented and how the coupling to an atmospheric model can be achieved.

scholarly journals Vorticity-Divergence semi-Lagrangian Global Atmospheric Model SL-AV20: Dynamical Core

2016 ◽  
Author(s):  
Mikhail Tolstykh ◽  
Vladimir Shashkin ◽  
Rostislav Fadeev ◽  
Gordey Goyman
Keyword(s):  
Numerical Solutions ◽  
Climate Modeling ◽  
Region Of Interest ◽  
Weather Forecast ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
Medium Range Weather Forecast ◽  
Variable Resolution ◽  
Dynamical Core ◽  
Global Atmospheric Model

Abstract. SL-AV (Semi-Lagranginan Absolute Vorticity) is a global atmospheric model. Its latest version SL-AV20 provides global operational medium-range weather forecast with 20 km resolution over Russia. The lower resolution configurations of SL-AV20 are being tested for seasonal prediction and climate modeling. The article presents the model dynamical core. Its main features are vorticity-divergence formulation at the unstaggered grid, high-order finite-difference approximations, semi-Lagrangian semi-implicit discretization and the reduced latitude-longitude grid with variable resolution in latitude. The accuracy of SL-AV20 numerical solutions using reduced lat-lon grid and the variable resolution in latitude is tested with two idealized testcases. The results agree well with other published model solutions. It is shown that the use of the reduced grid having up to 25 % less grid points than the regular grid does not significantly affect the accuracy. Variable resolution in latitude allows to improve the accuracy of solution in the region of interest.

scholarly journals Limits, Variability, and General Behavior of Statistical Predictability of the Midlatitude Atmosphere

2008 ◽  
Vol 65 (1) ◽  
pp. 263-275 ◽  
Author(s):  
Richard Kleeman
Keyword(s):  
Initial Conditions ◽  
Storm Track ◽  
Weather Forecast ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Statistical Prediction ◽  
Ensemble Spread ◽  
Winter Storm ◽  
Global Atmospheric Model ◽  
Summer Storm

Abstract The nature of statistical predictability is analyzed in a T42 global atmospheric model that is able to adequately capture the main features of the midlatitude atmosphere. Key novel features of the present study include very large prediction ensembles and information theoretic techniques. It is found globally that predictability declines in a quasi-linear fashion with time for short-term predictions (3–25 days), while for long ranges (30–45 days) there is an exponential tail. In general, beyond 45 days the prediction and climatological ensembles have essentially converged, which means that beyond that point, atmospheric initial conditions are irrelevant to atmospheric statistical prediction. Regional predictions show considerable variation in behavior. Both of the (northern) winter storm-track regions show a close-to-quasi-linear decline in predictability toward a cutoff at around 40 days. The (southern) summer storm track shows a much more exponential and considerably slower decline with a small amount of predictability still in evidence even at 90 days. Because the winter storm tracks dominate global variance the behavior of their predictability tends to dominate the global measure, except at longer lags. Variability in predictability with respect to initial conditions is also examined, and it is found that this is related more strongly to ensemble signal rather than ensemble spread. This result may serve to explain why the relation between weather forecast skill and ensemble spread is often observed to be significantly less than perfect. Results herein suggest that the ensemble signal as well as spread variations may be a major contributor to skill variations. Finally, it is found that the sensitivity of the calculated global predictability to changes in model horizontal resolution is not large; results from a T85 resolution model are not qualitatively all that different from the T42 case.

scholarly journals Seasonal range test run with Global Eta Framework

2017 ◽  
Vol 14 ◽  
pp. 247-251 ◽  
Author(s):  
Dragan Latinović ◽  
Sin Chan Chou ◽  
Miodrag Rančić
Keyword(s):  
Model Performance ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Curvilinear Coordinates ◽  
Smooth Transition ◽  
Precipitation Pattern ◽  
Global Atmospheric Model ◽  
Coordinate Lines ◽  
Cubed Sphere

Abstract. Global Eta Framework (GEF) is a global atmospheric model developed in general curvilinear coordinates and capable of running on arbitrary rectangular quasi-uniform spherical grids, using stepwise (Eta) representation of the terrain. In this study, the model is run on a cubed-sphere grid topology, in a version with uniform Jacobians (UJ), which provides equal-area grid cells, and a smooth transition of coordinate lines across the edges of the cubed-sphere. Within a project at the Brazilian Center for Weather Forecasts and Climate Studies (CPTEC), a nonhydrostatic version of this model is under development and will be applied for seasonal prediction studies. This note describes preliminary tests with the GEF on the UJ cubed-sphere in which model performance is evaluated in seasonal simulations at a horizontal resolution of approximately 25 km, running in the hydrostatic mode. Comparison of these simulations with the ERA-Interim reanalyses shows that the 850 hPa temperature is underestimated, while precipitation pattern is mostly underestimated in tropical continental regions and overestimated in tropical oceanic regions. Nevertheless, the model is still able to well capture the main seasonal climate characteristics. These results will be used as a control run in further tests with the nonhydrostatic version of the model.

THE ECMWF MULTI-TASKING WEATHER PREDICTION MODEL

1991 ◽  
Vol 02 (01) ◽  
pp. 158-186 ◽  
Author(s):  
A.J. SIMMONS ◽  
D. DENT
Keyword(s):  
Weather Prediction ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
General Introduction ◽  
Weather Forecasts ◽  
Operational Forecasting ◽  
Medium Range ◽  
Computational Aspects ◽  
Forecasting System ◽  
And Performance

A general introduction to numerical weather prediction is given. The development of the operational forecasting system of the European Centre for Medium-Range Weather Forecasts is summarized, and some results are presented illustrating sensitivity to the horizontal resolution of the atmospheric model, the factor which is most significant in determining computational needs. The spectral method used for the horizontal discretization is described, and computational aspects of its implementation on CRAY-1 and CRAY X-MP machines are discussed. The organization of the multi-tasking employed in the model is presented, and performance figures are given. There is a brief concluding discussion of some likely future developments in medium-range weather prediction.

Assessing Tracer Transport Algorithms and the Impact of Vertical Resolution in a Finite-Volume Dynamical Core

2012 ◽  
Vol 140 (5) ◽  
pp. 1620-1638 ◽  
Author(s):  
James Kent ◽  
Christiane Jablonowski ◽  
Jared P. Whitehead ◽  
Richard B. Rood
Keyword(s):  
Finite Volume ◽  
Vertical Component ◽  
Vertical Motion ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Vertical Resolution ◽  
Tracer Transport ◽  
Dynamical Core ◽  
Lagrangian Coordinate ◽  
The Impact

Abstract Modeling the transport of trace gases is an essential part of any atmospheric model. The tracer transport scheme in the Community Atmosphere Model finite-volume dynamical core (CAM-FV), which is part of the National Center for Atmospheric Research’s (NCAR’s) Community Earth System Model (CESM1), is investigated using multidimensional idealized advection tests. CAM-FV’s tracer transport algorithm makes use of one-dimensional monotonic limiters. The Colella–Sekora limiter, which is applied to increase accuracy where the data are smooth, is implemented into the CAM-FV framework, and compared with the more traditional monotonic limiter of the piecewise parabolic method (the default limiter). For 2D flow, CAM-FV splits dimensions, allowing overshoots and undershoots, with the Colella–Sekora limiter producing larger overshoots than the default limiter. The impact of vertical resolution is also explored. A vertical Lagrangian coordinate is used in CAM-FV, and is periodically remapped back to a fixed Eulerian grid. For purely vertical motion, it is found that less-frequent remapping of the Lagrangian coordinate in CAM-FV improves results. For full 3D tests, the vertical component of the tracer transport dominates the error and limits the overall accuracy. If the vertical resolution is inadequate, increasing the horizontal resolution has almost no effect on accuracy. This is because the vertical resolution currently used in CAM version 5 may not be sufficiently fine enough to resolve some atmospheric tracers and provide accurate vertical advection. Idealized tests using tracers in a gravity wave agree with these results.

scholarly journals Evaluation of the CAMS global atmospheric trace gas reanalysis 2003–2016 using aircraft campaign observations

2019 ◽  
Author(s):  
Yuting Wang ◽  
Yong-Feng Ma ◽  
Henk Eskes ◽  
Antje Inness ◽  
Johannes Flemming ◽  
...  
Keyword(s):  
Chemical Species ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Trace Gas ◽  
Weather Forecasts ◽  
Global Atmospheric Model ◽  
Reactive Gases ◽  
Monitoring Service ◽  
Atmospheric Trace Gas ◽  
Atmospheric Concentrations

Abstract. The Copernicus Atmosphere Monitoring Service (CAMS) operated by the European Centre for Medium Range Weather Forecasts (ECMWF) has produced a global reanalysis of aerosol and reactive gases (called CAMSRA) for the period 2003–2016. Space observations of ozone, carbon monoxide, NO2 and aerosol optical depth are assimilated by a 4-D Var method in the 60-layer ECMWF global atmospheric model, which for the reanalysis is operated at a horizontal resolution of about 80 km. As a contribution to the evaluation of the reanalysis, we compare atmospheric concentrations of different reactive species provided by the CAMS reanalysis with independent observational data gathered by airborne instrumentation during the field campaigns INTEX-A, INTEX-B, NEAQS-ITCT, ITOP, AMMA, ARCTAS, VOCALS, YAK-AEROSIB, HIPPO and KORUS-AQ. We show that the reanalysis reproduces rather successfully the observed concentrations of chemical species that are assimilated in the system including O3 and CO with the biases generally less than 20 %, but generally underestimate the concentrations of the primary hydrocarbons and secondary organic species. In some cases, large discrepancies also exist for fast-reacting radicals such as OH and HO2.

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