Error and Energy Budget Analysis of a Nonhydrostatic Stretched-Grid Global Atmospheric Model

Abstract A nonhydrostatic stretched-grid (SG) model is used to analyze the large-scale errors generated by stretching horizontal grids and their influence on a region of interest. Simulations by a fully compressible, nonhydrostatic global atmospheric model, the Nonhydrostatic Icosahedral Atmospheric Model (NICAM), and its SG regional model, stretched-NICAM, were performed for the months of March, April, and May of 2011 using various resolutions and stretching factors. A comparison of week-long accumulative precipitation amounts between the Tropical Rainfall Measuring Mission (TRMM) satellite data and the quasi-uniform and SG simulations showed that a stretched run better represents storms and associated precipitation because the errors generated in the outer regions with coarser grid spacing do not significantly affect the inner domain centered at the focal point. For season-long simulations, in one particular set of stretched runs with the focal point located in the eastern United States, the artificial suppression of baroclinic development of midlatitude eddies in the Southern Hemisphere weakened the eddy-driven polar-front jet (PFJ), which yielded a cold bias at mid- to high latitudes. However, in the Northern Hemisphere, in contrast, the aforementioned changes are less apparent. Therefore, for the SG runs, the mean temperature was maintained at the region of interest, and an increased amount of moderate to heavy precipitation, which is also frequently found in the TRMM data, was observed; thus, the benefits of increased resolution were realized. However, careful attention must be given when applying the SG model because a regional climate response to the change in the large-scale circulations may not be fully accounted for.

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Regional Climatic Features of the Arabian Peninsula

Atmosphere ◽

10.3390/atmos10040220 ◽

2019 ◽

Vol 10 (4) ◽

pp. 220 ◽

Cited By ~ 10

Author(s):

Patlakas ◽

Stathopoulos ◽

Flocas ◽

Kalogeri ◽

Kallos

Keyword(s):

Large Scale ◽

Arabian Peninsula ◽

Regional Climate ◽

Atmospheric Model ◽

Temporal Variations ◽

Spatial And Temporal Variations ◽

Spatial Distance ◽

Temperature Extremes ◽

Mean Temperature ◽

Maximum Temperatures

The climate of the Arabian Peninsula is characterized by significant spatial and temporal variations, due to its complex topography and the large-scale atmospheric circulation. Furthermore, the role of dust in the formation of regional climate is considered to be crucial. In this work, the regional climatology for the Arabian Peninsula has been studied by employing a high resolution state of the art atmospheric model that included sophisticated physical parameterization schemes and online treatment of natural aerosol particles. The simulations covered a 30-year period (1986–2015) with a temporal resolution of 3 h and a spatial distance of 9 km. The main focus was given to the spatial and temporal variations of mean temperature and temperature extremes, wind speed and direction, and relative humidity. The results were evaluated using in situ measurements indicating a good agreement. An examination of possible climatic changes during the present climate was also performed through a comprehensive analysis of the trends of mean temperature and temperature extremes. The statistical significant trend values were overall positive and increased over the northwestern parts of the examined area. Similar spatial distributions were found for the daily minimum and maximum temperatures. Higher positive values emerged for the daily maxima.

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

10.5194/gmd-2016-265 ◽

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.

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Physical Processes Controlling the Tide in the Tropical Lower Atmosphere Investigated Using a Comprehensive Numerical Model

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-17-0080.1 ◽

2017 ◽

Vol 74 (8) ◽

pp. 2467-2487 ◽

Cited By ~ 6

Author(s):

T. Sakazaki ◽

K. Hamilton

Keyword(s):

Linear Theory ◽

Large Scale ◽

Regional Climate ◽

Atmospheric Model ◽

Solar Heating ◽

Radiative Heating ◽

Lower Atmosphere ◽

Limited Area ◽

Daily Variations ◽

The Tropics

Abstract The lower-atmospheric circulation in the tropics is strongly influenced by large-scale daily variations referred to as atmospheric solar tides. Most earlier studies have used simplified linear theory to explain daily variations in the tropics. The present study employs a comprehensive limited-area atmospheric model and revisits some longstanding issues related to atmospheric tidal dynamics. The tides in the tropical lower atmosphere are realistically simulated in the control experiment with a near-global (75°S–75°N) version of the model. Sensitivity experiments with different aspects of the solar heating suppressed showed that the semidiurnal (S2) tide near the surface can be attributed roughly equally to stratospheric and tropospheric direct solar heating and that the diurnal (S1) tide is excited almost entirely by tropospheric direct solar heating as well as solar heating of Earth’s surface. Linear theory with forcing only by direct radiative heating predicts the phase of the S2 barometric oscillation should be ~0910 LT versus the ~0945 LT phase seen in low-latitude observations. The roles of (i) convective and latent heating and (ii) mechanical dissipation, in determining the S2 phase, are assessed in the model. It is found that the former effect delays the phase by ~25 min and the latter by ~5 min; these two effects together explain the observed phase. When the model is run in limited-area domains comparable to those used in typical regional climate studies the S2, but not S1, tide is found to be significantly weaker than observed, even using atmospheric reanalysis data to drive the lateral boundaries.

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The impact of deep convection representation in a global atmospheric model on the warm conveyor belt and jet stream during NAWDEX IOP6

10.5194/wcd-2021-38 ◽

2021 ◽

Author(s):

Gwendal Rivière ◽

Meryl Wimmer ◽

Philippe Arbogast ◽

Jean-Marcel Piriou ◽

Julien Delanoë ◽

...

Keyword(s):

Heating Rate ◽

Large Scale ◽

Deep Convection ◽

Atmospheric Model ◽

Conveyor Belt ◽

The Other ◽

Jet Stream ◽

Field Campaign ◽

Global Atmospheric Model ◽

The Impact

Abstract. The effect of parameterized deep convection on warm conveyor belt (WCB) activity and jet stream is investigated by performing simulations of an explosively-developing large-scale cyclone that occurred during the North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) field campaign using the Météo-France global atmospheric model ARPEGE. Three simulations differing only from their deep convection representation are analysed. The first one was performed with the Bougeault et al. (1985) scheme (B85), the second one with the Prognostic Condensates Microphysics and Transport (PCMT) scheme of Piriou et al. (2007), and the third one without any parameterized deep convection. In the latter simulation, the release of convective instability at the resolved scales of the model generates localized cells marked by strong heating with few degrees extent in longitude and latitude along the fronts. In runs with active parameterized deep convection (B85, PCMT), the heating rate is more homogeneously distributed along fronts as the instability release happens at sub-grid scales. This difference leads to more rapid and abrupt ascents in the WCB without parameterized deep convection, and more moderate but more sustained ascents with parameterized deep convection. While the number of WCB trajectories does not differ much between the three simulations, the averaged heating rates over the WCB trajectories exhibits distinct behavior. After one day of simulations, the upper-level heating rate is in average larger with B85 scheme leading to stronger potential vorticity (PV) destruction. The difference comes from the large-scale heating and not the parameterized heating.A comparison with (re)analyses and a large variety of airborne observations from the NAWDEX field campaign (Doppler radar, Doppler lidar, dropsondes) made during the coordinated flights of two aircraft in the WCB outflow region shows that B85 performs better in the representation of the double jet structure at 1-day lead time than the other two simulations. That can be attributed to the more active WCB at upper levels. However this effect is too strong and that simulation becomes less realistic at longer forecast range (1.5 to 2 days) than the other ones. The simulation with PCMT scheme has an intermediate behavior between the one with B85 scheme and without parameterized deep convection but its impact on the jet stream is closer to the latter one. Finally, additional numerical experiments show that main differences in the impact on the jet between PCMT and B85 largely come from the chosen closure, the former being based on CAPE and the latter on moisture convergence.

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Future Change of Western North Pacific Typhoons: Projections by a 20-km-Mesh Global Atmospheric Model*

Journal of Climate ◽

10.1175/2010jcli3723.1 ◽

2011 ◽

Vol 24 (4) ◽

pp. 1154-1169 ◽

Cited By ~ 120

Author(s):

Hiroyuki Murakami ◽

Bin Wang ◽

Akio Kitoh

Keyword(s):

North Pacific ◽

General Circulation ◽

Western North Pacific ◽

Large Scale ◽

Vertical Wind Shear ◽

Circulation Model ◽

Atmospheric Model ◽

Japan Meteorological Agency ◽

Global Atmospheric Model ◽

Meteorological Research Institute

Abstract Projected future changes in tropical cyclone (TC) activity over the western North Pacific (WNP) under the Special Report on Emissions Scenarios (SRES) A1B emission scenario were investigated using a 20-km-mesh, very-high-resolution Meteorological Research Institute (MRI)–Japan Meteorological Agency (JMA) atmospheric general circulation model. The present-day (1979–2003) simulation yielded reasonably realistic climatology and interannual variability for TC genesis frequency and tracks. The future (2075–99) projection indicates (i) a significant reduction (by about 23%) in both TC genesis number and frequency of occurrence primarily during the late part of the year (September–December), (ii) an eastward shift in the positions of the two prevailing northward-recurving TC tracks during the peak TC season (July–October), and (iii) a significant reduction (by 44%) in TC frequency approaching coastal regions of Southeast Asia. The changes in occurrence frequency are due in part to changes in large-scale steering flows, but they are due mainly to changes in the locations of TC genesis; fewer TCs will form in the western portion of the WNP (west of 145°E), whereas more storms will form in the southeastern quadrant of the WNP (10°–20°N, 145°–160°E). Analysis of the genesis potential index reveals that the reduced TC genesis in the western WNP is due mainly to in situ weakening of large-scale ascent and decreasing midtropospheric relative humidity, which are associated with the enhanced descent of the tropical overturning circulation. The analysis also indicates that enhanced TC genesis in the southeastern WNP is due to increased low-level cyclonic vorticity and reduced vertical wind shear. These changes appear to be critically dependent on the spatial pattern of future sea surface temperature; therefore, it is necessary to conduct ensemble projections with a range of SST spatial patterns to understand the degree and distribution of uncertainty in future projections.

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A Multiscale Nonhydrostatic Atmospheric Model Using Centroidal Voronoi Tesselations and C-Grid Staggering

Monthly Weather Review ◽

10.1175/mwr-d-11-00215.1 ◽

2012 ◽

Vol 140 (9) ◽

pp. 3090-3105 ◽

Cited By ~ 241

Author(s):

William C. Skamarock ◽

Joseph B. Klemp ◽

Michael G. Duda ◽

Laura D. Fowler ◽

Sang-Hun Park ◽

...

Keyword(s):

Large Scale ◽

Regional Climate ◽

Time Integration ◽

Atmospheric Model ◽

Horizontal Resolution ◽

Variable Resolution ◽

Transition Zones ◽

Voronoi Tesselations ◽

Scale Models ◽

Large Scale Flow

Abstract The formulation of a fully compressible nonhydrostatic atmospheric model called the Model for Prediction Across Scales–Atmosphere (MPAS-A) is described. The solver is discretized using centroidal Voronoi meshes and a C-grid staggering of the prognostic variables, and it incorporates a split-explicit time-integration technique used in many existing nonhydrostatic meso- and cloud-scale models. MPAS can be applied to the globe, over limited areas of the globe, and on Cartesian planes. The Voronoi meshes are unstructured grids that permit variable horizontal resolution. These meshes allow for applications beyond uniform-resolution NWP and climate prediction, in particular allowing embedded high-resolution regions to be used for regional NWP and regional climate applications. The rationales for aspects of this formulation are discussed, and results from tests for nonhydrostatic flows on Cartesian planes and for large-scale flow on the sphere are presented. The results indicate that the solver is as accurate as existing nonhydrostatic solvers for nonhydrostatic-scale flows, and has accuracy comparable to existing global models using icosahedral (hexagonal) meshes for large-scale flows in idealized tests. Preliminary full-physics forecast results indicate that the solver formulation is robust and that the variable-resolution-mesh solutions are well resolved and exhibit no obvious problems in the mesh-transition zones.

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Sensitivity of simulated temperature, precipitation, and global radiation to different WRF configurations over the Carpathian Basin for regional climate applications

Climate Dynamics ◽

10.1007/s00382-020-05416-x ◽

2020 ◽

Vol 55 (9-10) ◽

pp. 2849-2866

Author(s):

Ákos János Varga ◽

Hajnalka Breuer

Keyword(s):

Large Scale ◽

Regional Climate ◽

Global Radiation ◽

Wrf Model ◽

Carpathian Basin ◽

Shortwave Radiation ◽

Cold Bias ◽

Parameterization Schemes ◽

Downward Shortwave Radiation ◽

Basin Region

Abstract In this study, the Weather Research and Forecasting (WRF) model is used to produce short-term regional climate simulations with several configurations for the Carpathian Basin region. The goal is to evaluate the performance of the model and analyze its sensitivity to different physical and dynamical settings, and input data. Fifteen experiments were conducted with WRF at 10 km resolution for the year 2013. The simulations differ in terms of configuration options such as the parameterization schemes, the hydrostatic and non-hydrostatic dynamical cores, the initial and boundary conditions (ERA5 and ERA-Interim reanalyses), the number of vertical levels, and the length of the spin-up period. E-OBS dataset 2 m temperature, total precipitation, and global radiation are used for validation. Temperature underestimation reaches 4–7 °C for some experiments and can be reduced by certain physics scheme combinations. The cold bias in winter and spring is mainly caused by excessive snowfall and too persistent snow cover, as revealed by comparison with satellite-based observations and a test simulation without snow on the surface. Annual precipitation is overestimated by 0.6–3.8 mm day−1, with biases mainly accumulating in the period driven by large-scale weather processes. Downward shortwave radiation is underestimated all year except in the months dominated by locally forced phenomena (May to August) when a positive bias prevails. The incorporation of downward shortwave radiation to the validation variables increased the understanding of underlying problems with the parameterization schemes and highlighted false model error compensations.

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Variability of daily winter wind speed distribution over Northern Europe during the past millennium in regional and global climate simulations

Climate of the Past Discussions ◽

10.5194/cpd-11-1479-2015 ◽

2015 ◽

Vol 11 (2) ◽

pp. 1479-1518 ◽

Cited By ~ 1

Author(s):

S. E. Bierstedt ◽

B. Hünicke ◽

E. Zorita ◽

S. Wagner ◽

J. J. Gómez-Navarro

Keyword(s):

Wind Speed ◽

North Atlantic ◽

Large Scale ◽

Global Climate ◽

Regional Climate ◽

Atmospheric Model ◽

The North ◽

Wind Speed Distribution ◽

Climate Simulations ◽

The North Atlantic Oscillation

Abstract. We analyse the variability of the probability distribution of daily wind speed in wintertime over Northern and Central Europe in a series of global and regional climate simulations covering the last centuries, and reanalysis products covering approximately the last 60 years. The focus of the study lies in identifying the link between the variations in the wind speed distribution to the regional near-surface temperature, to the meridional temperature gradient and to the North Atlantic Oscillation. The climate simulations comprise three simulations, each conducted with a global climate model that includes a different version of the atmospheric model ECHAM. Two of these global simulations have been regionalised with the regional climate models MM5 and CCLM. The reanalysis products are the global NCEP/NCAR meteorological reanalysis version 1 and a regional reanalysis conducted with a regional atmospheric model driven at its domain boundaries by the NCEP/NCAR reanalysis. Our main result is that the link between the daily wind distribution and the regional climate drivers is strongly model dependent. The global models tend to behave similarly, although they show some discrepancies. The two regional models also tend to behave similarly to each other, but surprisingly the results derived from each regional model strongly deviates from the results derived from its driving global model. The links between wind speed and large-scale drivers derived from the reanalysis data sets overall tend to resemble those of the global models. In addition, considering multi-centennial time scales, we find in two global simulations a long term tendency for the probability distribution of daily wind speed to widen through the last centuries. The cause for this widening is likely the effect of the deforestation prescribed in these simulations. We conclude that no clear systematic relationship between the mean temperature, the temperature gradient and/or the North Atlantic Oscillation, with the daily wind speed statistics can be inferred from these simulations. The understanding of past and future changes in the distribution of wind speeds, and thus of wind speed extremes, will require a~detailed analysis of the representation of the interaction between large-scale and small-scale dynamics.

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The impact of deep convection representation in a global atmospheric model on the warm conveyor belt and jet stream during NAWDEX IOP6

Weather and Climate Dynamics ◽

10.5194/wcd-2-1011-2021 ◽

2021 ◽

Vol 2 (4) ◽

pp. 1011-1031

Author(s):

Gwendal Rivière ◽

Meryl Wimmer ◽

Philippe Arbogast ◽

Jean-Marcel Piriou ◽

Julien Delanoë ◽

...

Keyword(s):

Heating Rate ◽

Large Scale ◽

Deep Convection ◽

Atmospheric Model ◽

Conveyor Belt ◽

The Other ◽

Jet Stream ◽

Field Campaign ◽

Global Atmospheric Model ◽

The Impact

Abstract. The effect of parameterized deep convection on warm conveyor belt (WCB) activity and the jet stream is investigated by performing simulations of an explosively developing large-scale cyclone that occurred during the North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) field campaign using the Météo-France global atmospheric model ARPEGE. Three simulations differing only from their deep convection representation are analysed. The first one was performed with the Bougeault (1985) scheme (B85), the second one with the Prognostic Condensates Microphysics and Transport (PCMT) scheme of Piriou et al. (2007), and the third one without any parameterized deep convection. In the latter simulation, the release of convective instability at the resolved scales of the model generates localized cells marked by strong heating with few degrees extent in longitude and latitude along the fronts. In runs with active parameterized deep convection (B85, PCMT), the heating rate is more homogeneously distributed along fronts as the instability release happens at subgrid scales. This difference leads to more rapid and abrupt ascents in the WCB without parameterized deep convection and more moderate but more sustained ascents with parameterized deep convection. While the number of WCB trajectories does not differ much between the three simulations, the averaged heating rates over the WCB trajectories exhibits distinct behaviour. After 1 d of simulations, the upper-level heating rate is on average larger, with the B85 scheme leading to stronger potential vorticity (PV) destruction. The difference comes from the resolved sensible and latent heating and not the parameterized one. A comparison with (re)analyses and a large variety of airborne observations from the NAWDEX field campaign (Doppler radar, Doppler lidar, dropsondes) made during the coordinated flights of two aircraft in the WCB outflow region shows that B85 performs better in the representation of the double jet structure at 1 d lead time than the other two simulations. That can be attributed to the more active WCB at upper levels. However, this effect is too strong and that simulation becomes less realistic than the other ones at forecast ranges beyond 1.5 d. The simulation with the PCMT scheme has an intermediate behaviour between the one with the B85 scheme and without parameterized deep convection, but its impact on the jet stream is closer to the latter one. Finally, additional numerical experiments show that main differences in the impact on the jet between PCMT and B85 largely come from the chosen closure, with the former being based on CAPE and the latter on moisture convergence.

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Impact of a Dense Surface Network on High-Resolution Dynamical Downscaling via Observation Nudging

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-20-0071.1 ◽

2020 ◽

Vol 59 (10) ◽

pp. 1655-1670

Author(s):

Xue Yi ◽

Deqin Li ◽

Chunyu Zhao ◽

Lidu Shen ◽

Xiaoyu Zhou

Keyword(s):

High Resolution ◽

Large Scale ◽

Dynamical Downscaling ◽

Regional Climate ◽

Wrf Model ◽

Small Scale ◽

Cold Bias ◽

Surface Network ◽

Density Surface ◽

Surface Observations

AbstractHigh-density surface networks have become available in recent years in a number of regions throughout the world, but their utility in high-resolution dynamic downscaling has not been examined. As an attempt to fill such a gap, a suite of high-resolution (4 km) dynamical downscaling simulations is developed in this study with the Weather Research and Forecasting (WRF) Model and observation nudging over Liaoning in northeastern China. Three experiments, including no nudging (CTL), analysis nudging (AN), and combined analysis nudging and observation nudging with surface observations (AON), are conducted to downscale the CFSv2 reanalysis with the WRF Model for the year 2015. The three 1-yr regional climate simulations were compared with the independent surface observations. The results show that observational nudging can improve the simulation of surface variables, including temperature, wind speed, humidity, and pressure, more than nudging large-scale driving data with AN alone. The two nudging simulations can improve the cold bias for the temperature of the WRF Model. For precipitation, both the simulations with AN and observation nudging can capture the pattern of precipitation; however, with the introduction of small-scale information at the surface, AON cannot further improve the simulation of precipitation.

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