scholarly journals Seasonal Performance of a Nonhydrostatic Global Atmospheric Model on a Cubed‐Sphere Grid

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Jung‐Eun Esther Kim ◽  
Myung‐Seo Koo ◽  
Changhyun Yoo ◽  
Song‐You Hong
Keyword(s):  
Atmospheric Model ◽  
Global Atmospheric Model ◽  
Seasonal Performance ◽  
Cubed Sphere

scholarly journals fv3gfs-wrapper: a Python wrapper of the FV3GFS atmospheric model

2021 ◽  
Vol 14 (7) ◽  
pp. 4401-4409
Author(s):  
Jeremy McGibbon ◽  
Noah D. Brenowitz ◽  
Mark Cheeseman ◽  
Spencer K. Clark ◽  
Johann P. S. Dahm ◽  
...  
Keyword(s):  
Model Performance ◽  
Atmospheric Model ◽  
Simulation Software ◽  
Storage Model ◽  
High Productivity ◽  
Global Atmospheric Model ◽  
Performance Requirements ◽  
Wide Range ◽  
Stringent Performance ◽  
Cubed Sphere

Abstract. Simulation software in geophysics is traditionally written in Fortran or C++ due to the stringent performance requirements these codes have to satisfy. As a result, researchers who use high-productivity languages for exploratory work often find these codes hard to understand, hard to modify, and hard to integrate with their analysis tools. fv3gfs-wrapper is an open-source Python-wrapped version of the NOAA (National Oceanic and Atmospheric Administration) FV3GFS (Finite-Volume Cubed-Sphere Global Forecast System) global atmospheric model, which is coded in Fortran. The wrapper provides simple interfaces to progress the Fortran main loop and get or set variables used by the Fortran model. These interfaces enable a wide range of use cases such as modifying the behavior of the model, introducing online analysis code, or saving model variables and reading forcings directly to and from cloud storage. Model performance is identical to the fully compiled Fortran model, unless routines to copy the state in and out of the model are used. This copy overhead is well within an acceptable range of performance and could be avoided with modifications to the Fortran source code. The wrapping approach is outlined and can be applied similarly in other Fortran models to enable more productive scientific workflows.

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.

scholarly journals An efficient training scheme for supermodels

2017 ◽  
Vol 8 (2) ◽  
pp. 429-438 ◽  
Author(s):  
Francine J. Schevenhoven ◽  
Frank M. Selten
Keyword(s):  
Climate Models ◽  
State Of The Art ◽  
Atmospheric Model ◽  
High Dimensional ◽  
Model Errors ◽  
Global Atmospheric Model ◽  
Training Scheme ◽  
Skill Scores ◽  
Weather And Climate ◽  
The Individual

Abstract. Weather and climate models have improved steadily over time as witnessed by objective skill scores, although significant model errors remain. Given these imperfect models, predictions might be improved by combining them dynamically into a so-called supermodel. In this paper a new training scheme to construct such a supermodel is explored using a technique called cross pollination in time (CPT). In the CPT approach the models exchange states during the prediction. The number of possible predictions grows quickly with time, and a strategy to retain only a small number of predictions, called pruning, needs to be developed. The method is explored using low-order dynamical systems and applied to a global atmospheric model. The results indicate that the CPT training is efficient and leads to a supermodel with improved forecast quality as compared to the individual models. Due to its computational efficiency, the technique is suited for application to state-of-the art high-dimensional weather and climate models.

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 Global atmospheric model for mercury including oxidation by bromine atoms

2010 ◽  
Vol 10 (24) ◽  
pp. 12037-12057 ◽  
Author(s):  
C. D. Holmes ◽  
D. J. Jacob ◽  
E. S. Corbitt ◽  
J. Mao ◽  
X. Yang ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Model ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Deposition Flux ◽  
Mercury Deposition ◽  
Photochemical Reduction ◽  
Global Atmospheric Model ◽  
Summer Maximum ◽  
Southeast Us

Abstract. Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br) as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model) and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model). We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM) concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by the Hg + Br model. Model comparisons to observed wet deposition fluxes of mercury in the US and Europe show general consistency. However the Hg + Br model does not capture the summer maximum over the southeast US because of low subtropical Br concentrations while the Hg + OH/O3 model does. Vertical profiles measured from aircraft show a decline of Hg0 above the tropopause that can be captured by both the Hg + Br and Hg + OH/O3 models, except in Arctic spring where the observed decline is much steeper than simulated by either model; we speculate that oxidation by Cl species might be responsible. The Hg + Br and Hg + OH/O3 models yield similar global budgets for the cycling of mercury between the atmosphere and surface reservoirs, but the Hg + Br model results in a much larger fraction of mercury deposited to the Southern Hemisphere oceans.

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