scholarly journals The Navy Global Environmental Model

Oceanography ◽  
2014 ◽  
Vol 27 (3) ◽  
pp. 116-125 ◽  
Author(s):  
Timothy Hogan ◽  
Ming Liu ◽  
James Ridout ◽  
Melinda Peng ◽  
Timothy Whitcomb ◽  
...  
Keyword(s):  
Environmental Model ◽  
Global Environmental

scholarly journals U.K. HiGEM: The New U.K. High-Resolution Global Environment Model—Model Description and Basic Evaluation

2009 ◽  
Vol 22 (8) ◽  
pp. 1861-1896 ◽  
Author(s):  
L. C. Shaffrey ◽  
I. Stevens ◽  
W. A. Norton ◽  
M. J. Roberts ◽  
P. L. Vidale ◽  
...  
Keyword(s):  
High Resolution ◽  
Tropical Pacific ◽  
Model Description ◽  
Small Scale ◽  
Environmental Model ◽  
Instability Waves ◽  
Tropical Instability Waves ◽  
Global Environmental ◽  
The Impact ◽  
The Tropical Pacific

Abstract This article describes the development and evaluation of the U.K.’s new High-Resolution Global Environmental Model (HiGEM), which is based on the latest climate configuration of the Met Office Unified Model, known as the Hadley Centre Global Environmental Model, version 1 (HadGEM1). In HiGEM, the horizontal resolution has been increased to 0.83° latitude × 1.25° longitude for the atmosphere, and 1/3° × 1/3° globally for the ocean. Multidecadal integrations of HiGEM, and the lower-resolution HadGEM, are used to explore the impact of resolution on the fidelity of climate simulations. Generally, SST errors are reduced in HiGEM. Cold SST errors associated with the path of the North Atlantic drift improve, and warm SST errors are reduced in upwelling stratocumulus regions where the simulation of low-level cloud is better at higher resolution. The ocean model in HiGEM allows ocean eddies to be partially resolved, which dramatically improves the representation of sea surface height variability. In the Southern Ocean, most of the heat transports in HiGEM is achieved by resolved eddy motions, which replaces the parameterized eddy heat transport in the lower-resolution model. HiGEM is also able to more realistically simulate small-scale features in the wind stress curl around islands and oceanic SST fronts, which may have implications for oceanic upwelling and ocean biology. Higher resolution in both the atmosphere and the ocean allows coupling to occur on small spatial scales. In particular, the small-scale interaction recently seen in satellite imagery between the atmosphere and tropical instability waves in the tropical Pacific Ocean is realistically captured in HiGEM. Tropical instability waves play a role in improving the simulation of the mean state of the tropical Pacific, which has important implications for climate variability. In particular, all aspects of the simulation of ENSO (spatial patterns, the time scales at which ENSO occurs, and global teleconnections) are much improved in HiGEM.

Evolution of the upper tropospheric outflow in Hurricanes Iselle and Julio (2014) in the Navy Global Environmental Model (NAVGEM) analyses and in satellite and dropsonde observations

2016 ◽  
Vol 121 (22) ◽  
pp. 13,273-13,286 ◽  
Author(s):  
Bradford S. Barrett ◽  
Elizabeth R. Sanabia ◽  
Sara C. Reynolds ◽  
Julie K. Stapleton ◽  
Anthony L. Borrego
Keyword(s):  
Environmental Model ◽  
Global Environmental

scholarly journals Impact of the modal aerosol scheme GLOMAP-mode on aerosol forcing in the Hadley Centre Global Environmental Model

2013 ◽  
Vol 13 (6) ◽  
pp. 3027-3044 ◽  
Author(s):  
N. Bellouin ◽  
G. W. Mann ◽  
M. T. Woodhouse ◽  
C. Johnson ◽  
K. S. Carslaw ◽  
...  
Keyword(s):  
Residence Time ◽  
Large Scale ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Environmental Model ◽  
Anthropogenic Aerosol ◽  
Microphysics Scheme ◽  
Aerosol Forcing ◽  
Global Environmental ◽  
Hadley Centre

Abstract. The Hadley Centre Global Environmental Model (HadGEM) includes two aerosol schemes: the Coupled Large-scale Aerosol Simulator for Studies in Climate (CLASSIC), and the new Global Model of Aerosol Processes (GLOMAP-mode). GLOMAP-mode is a modal aerosol microphysics scheme that simulates not only aerosol mass but also aerosol number, represents internally-mixed particles, and includes aerosol microphysical processes such as nucleation. In this study, both schemes provide hindcast simulations of natural and anthropogenic aerosol species for the period 2000–2006. HadGEM simulations of the aerosol optical depth using GLOMAP-mode compare better than CLASSIC against a data-assimilated aerosol re-analysis and aerosol ground-based observations. Because of differences in wet deposition rates, GLOMAP-mode sulphate aerosol residence time is two days longer than CLASSIC sulphate aerosols, whereas black carbon residence time is much shorter. As a result, CLASSIC underestimates aerosol optical depths in continental regions of the Northern Hemisphere and likely overestimates absorption in remote regions. Aerosol direct and first indirect radiative forcings are computed from simulations of aerosols with emissions for the year 1850 and 2000. In 1850, GLOMAP-mode predicts lower aerosol optical depths and higher cloud droplet number concentrations than CLASSIC. Consequently, simulated clouds are much less susceptible to natural and anthropogenic aerosol changes when the microphysical scheme is used. In particular, the response of cloud condensation nuclei to an increase in dimethyl sulphide emissions becomes a factor of four smaller. The combined effect of different 1850 baselines, residence times, and abilities to affect cloud droplet number, leads to substantial differences in the aerosol forcings simulated by the two schemes. GLOMAP-mode finds a present-day direct aerosol forcing of −0.49 W m−2 on a global average, 72% stronger than the corresponding forcing from CLASSIC. This difference is compensated by changes in first indirect aerosol forcing: the forcing of −1.17 W m−2 obtained with GLOMAP-mode is 20% weaker than with CLASSIC. Results suggest that mass-based schemes such as CLASSIC lack the necessary sophistication to provide realistic input to aerosol-cloud interaction schemes. Furthermore, the importance of the 1850 baseline highlights how model skill in predicting present-day aerosol does not guarantee reliable forcing estimates. Those findings suggest that the more complex representation of aerosol processes in microphysical schemes improves the fidelity of simulated aerosol forcings.

scholarly journals Implementation of a Stochastic Eddy-Diffusivity/Mass-Flux Parameterization into the Navy Global Environmental Model

2014 ◽  
Vol 29 (6) ◽  
pp. 1374-1390 ◽  
Author(s):  
Kay Sušelj ◽  
Timothy F. Hogan ◽  
João Teixeira
Keyword(s):  
Boundary Layer ◽  
Mass Flux ◽  
Weather Forecasting ◽  
Eddy Diffusivity ◽  
Shallow Convection ◽  
Environmental Model ◽  
Eddy Simulation ◽  
Global Environmental ◽  
Current Implementation ◽  
Flux Parameterization

Abstract A unified boundary layer and shallow convection parameterization based on a stochastic eddy-diffusivity/mass-flux (EDMF) approach is implemented and tested in the Navy Global Environmental Model (NAVGEM). The primary goals of this work are to improve the representation of convectively driven boundary layers and the coupling between the boundary layer and cumulus regions. Within the EDMF framework the subgrid vertical fluxes are calculated as a sum of an eddy-diffusivity part, which in the current implementation is based on the approach developed by Louis in the late 1970s, and a stochastic mass-flux parameterization. The mass-flux parameterization is a model for both dry and moist convective thermals. Dry thermals, which represent surface-forced coherent structures in a flow, provide countergradient mixing in the boundary layer and, if conditions permit, are the roots for moist thermals. Moist thermals represent shallow convective clouds. The new parameterization implemented in a single-column model (SCM) version of NAVGEM is shown to be able to realistically simulate a variety of dry and moist convective cases. The NAVGEM SCM results are validated against large-eddy-simulation results. The skill of NAVGEM as a global weather forecasting model is considerably improved with the new EDMF parameterization. The EDMF parameterization became part of the operational NAVGEM in November 2013.

scholarly journals The Physical Properties of the Atmosphere in the New Hadley Centre Global Environmental Model (HadGEM1). Part II: Aspects of Variability and Regional Climate

2006 ◽  
Vol 19 (7) ◽  
pp. 1302-1326 ◽  
Author(s):  
M. A. Ringer ◽  
G. M. Martin ◽  
C. Z. Greeves ◽  
T. J. Hinton ◽  
P. M. James ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Storm Tracks ◽  
Madden Julian Oscillation ◽  
Environmental Model ◽  
Global Environmental ◽  
Equatorial Wave ◽  
Asian Summer ◽  
Hadley Centre

Abstract The performance of the atmospheric component of the new Hadley Centre Global Environmental Model (HadGEM1) is assessed in terms of its ability to represent a selection of key aspects of variability in the Tropics and extratropics. These include midlatitude storm tracks and blocking activity, synoptic variability over Europe, and the North Atlantic Oscillation together with tropical convection, the Madden–Julian oscillation, and the Asian summer monsoon. Comparisons with the previous model, the Third Hadley Centre Coupled Ocean–Atmosphere GCM (HadCM3), demonstrate that there has been a considerable increase in the transient eddy kinetic energy (EKE), bringing HadGEM1 into closer agreement with current reanalyses. This increase in EKE results from the increased horizontal resolution and, in combination with the improved physical parameterizations, leads to improvements in the representation of Northern Hemisphere storm tracks and blocking. The simulation of synoptic weather regimes over Europe is also greatly improved compared to HadCM3, again due to both increased resolution and other model developments. The variability of convection in the equatorial region is generally stronger and closer to observations than in HadCM3. There is, however, still limited convective variance coincident with several of the observed equatorial wave modes. Simulation of the Madden–Julian oscillation is improved in HadGEM1: both the activity and interannual variability are increased and the eastward propagation, although slower than observed, is much better simulated. While some aspects of the climatology of the Asian summer monsoon are improved in HadGEM1, the upper-level winds are too weak and the simulation of precipitation deteriorates. The dominant modes of monsoon interannual variability are similar in the two models, although in HadCM3 this is linked to SST forcing, while in HadGEM1 internal variability dominates. Overall, analysis of the phenomena considered here indicates that HadGEM1 performs well and, in many important respects, improves upon HadCM3. Together with the improved representation of the mean climate, this improvement in the simulation of atmospheric variability suggests that HadGEM1 provides a sound basis for future studies of climate and climate change.

scholarly journals The Physical Properties of the Atmosphere in the New Hadley Centre Global Environmental Model (HadGEM1). Part I: Model Description and Global Climatology

2006 ◽  
Vol 19 (7) ◽  
pp. 1274-1301 ◽  
Author(s):  
G. M. Martin ◽  
M. A. Ringer ◽  
V. D. Pope ◽  
A. Jones ◽  
C. Dearden ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
General Circulation ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Radiative Properties ◽  
Model Description ◽  
Environmental Model ◽  
Global Environmental ◽  
Hadley Centre

Abstract The atmospheric component of the new Hadley Centre Global Environmental Model (HadGEM1) is described and an assessment of its mean climatology presented. HadGEM1 includes substantially improved representations of physical processes, increased functionality, and higher resolution than its predecessor, the Third Hadley Centre Coupled Ocean–Atmosphere General Circulation Model (HadCM3). Major developments are the use of semi-Lagrangian instead of Eulerian advection for both dynamical and tracer fields; new boundary layer, gravity wave drag, microphysics, and sea ice schemes; and major changes to the convection, land surface (including tiled surface characteristics), and cloud schemes. There is better coupling between the atmosphere, land, ocean, and sea ice subcomponents and the model includes an interactive aerosol scheme, representing both the first and second indirect effects. Particular focus has been placed on improving the processes (such as clouds and aerosol) that are most uncertain in projections of climate change. These developments lead to a significantly more realistic simulation of the processes represented, the most notable improvements being in the hydrological cycle, cloud radiative properties, the boundary layer, the tropopause structure, and the representation of tracers.

scholarly journals Caracterização dos Diferentes Tipos de El Niño e seus Impactos na América do Sul a Partir de Dados Observados e Modelados

2019 ◽  
Vol 34 (1) ◽  
pp. 43-67
Author(s):  
Juarez Viegas ◽  
Rita Valéria Andreoli ◽  
Mary Toshie Kayano ◽  
Luiz Antonio Candido ◽  
Rodrigo Augusto Ferreira de Souza ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Coupled Model ◽  
System Model ◽  
Earth System ◽  
Model Intercomparison ◽  
Environmental Model ◽  
Global Environmental ◽  
Intercomparison Project ◽  
Hadley Centre

Resumo Estudos recentes têm apontado para a existência de dois tipos de eventos de El Niño (EN): EN do Pacífico oriental ou Canônico (EP, sigla em inglês) e EN do Pacífico Central ou Modoki (CP, sigla em inglês). Neste estudo, foram utilizados dados observados e de três modelos do Coupled Model Intercomparison Project phase 5 (CMIP5) para avaliar o impacto dos dois tipos de EN na precipitação da América do Sul desde o trimestre de Junho-Agosto do ano inicial do evento até Março-Maio do ano seguinte. O modelo do Centre National de Recherches Météorologiques (CNRM-CM5) apresentou o melhor desempenho para reproduzir os padrões anômalos observados de TSM para os tipos de EN CP e EP. O padrão anômalo da precipitação observada associado a eventos EN foi mais marcante durante o verão austral. No caso do EN EP, tal padrão caracterizou-se por precipitação acima (abaixo) da normal no sudeste (norte/noroeste) da América do Sul. Este padrão foi reproduzido pelos modelos CNRM-CM5 e Hadley Centre Global Environmental Model (HadGEM2-ES). O Max Plank Institute Earth System model (MPI-ESM-LR) reproduziu a redução de chuva no norte, porém não reproduziu o aumento anômalo no sudeste e redução no noroeste do continente. No caso do EN CP, o impacto observado nas chuvas da América do Sul durante o verão caracterizou-se por escassez (excesso) no norte/noroeste (sudeste). Este padrão foi reproduzido pelos modelos, entretanto, os modelos HadGEM2-ES e MPI-ESM-LR mostraram índices pluviométricos no nordeste do Brasil menores do que os observados. As diferenças na representação dos padrões de teleconexões em resposta ao EN explicam as diferenças entre os padrões simulados.

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