Mesometeorological Model Research Articles

Simulation of European air quality by WRF–CMAQ models using AQMEII-2 infrastructure

The air quality modeling system WRF–CMAQ was applied to the European domain for the year 2010 in the frame of the Air Quality Model Evaluation International Initiative (AQMEII), Phase 2. The model system was set up for a domain of 5000×5000 km2 size with horizontal resolution of 25km. The emissions at European level were available through AQMEII and further processed in a way to feed the chemistry transport model CMAQ. The meso-meteorological model WRF was driven by NCEP GFS data with 1°×1° resolution. The chemical boundary conditions were extracted from MACC global simulation data. Model performance was investigated by means of AQMEII-2 web based evaluation platform and the monitoring data gathered for this activity. A preliminary model evaluation for ozone, nitrogen dioxide and particulate matter was conducted. The statistical analysis was based on comparison between simulated and observed concentrations at different type of surface stations in the EU wide domain (rural, urban, suburban), as well as for selected four cities. Model performance was characterized by overestimation for ozone and underestimation for the other pollutants. The relative statistical indicators were discussed also in view of recently published performance criteria.

Modeled large-scale warming impacts on summer California coastal-cooling trends

[1] Regional Atmospheric Modeling System (RAMS) meso-meteorological model simulations with a horizontal grid resolution of 4 km on an inner grid over the South Coast Air Basin of California were used to investigate effects from long-term (i.e., past 35 years) large-scale warming impacts on coastal flows. Comparison of present- and past-climate simulations showed significant increases in summer daytime sea breeze activity by up to 1.5 m s−1 (in the onshore component) and a concurrent coastal cooling of average-daily peak temperatures of up to −1.6°C, both of which support observations that the latter is an indirect “reverse reaction” to the large-scale warming of inland areas.

Chemical weather forecasting: a new concept of integrated modelling

Abstract. During the last decade a new field of atmospheric modelling – the chemical weather forecasting (CWF) – is quickly developing and growing. However, in the most of the current studies and publications, this field is considered in a simplified concept of the off-line running chemical transport models with operational numerical weather prediction (NWP) data as a driver. A new concept and methodology considering the chemical weather as two-way interacting meteorological weather and chemical composition of the atmosphere is suggested and discussed. The on-line integration of mesometeorological models and atmospheric aerosol and chemical transport models gives a possibility to utilize all meteorological 3-D fields in the chemical transport model at each time step and to consider feedbacks of air pollution (e.g. urban aerosols) on meteorological processes/climate forcing and then on the atmospheric chemical composition. This very promising way for future atmospheric simulation systems (as a part of and a step to Earth System Modelling) will lead to a new generation of models for meteorological, environmental and chemical weather forecasting. The methodology how to realise the suggested integrated CWF concept is demonstrated on the example of the European Enviro-HIRLAM integrated system. The importance of different feedback mechanisms for CWF is also discussed in the paper.

NUMERICAL STUDY OF WIND VELOCITY MEASURED ON THE ROOFTOP OF A TALL BUILDING IN CITY

The measurement wind velocity on the rooftop of the tall building is usually utilized as a reference wind velocity. However, after many new tall buildings have been constructed around the specified tall building, it becomes difficult to use the rooftop data as a reference. While, the wind velocity predicted by the meso-meteorological model (MM5) without the urban-canopy model has been little affected by surface shapes of buildings on the ground and expected to be accurate at sufficiently higher position. This paper examines the regional representativeness of MM5 wind velocity data by comparing the full-scale measurement data at open area. Also, in the case of measurement point within the urban canopy, rooftop wind velocity computed by large-eddy simulation (LES) is estimated by matching MM5 wind profile. The method determining an appropriate height for a reference wind velocity is provided.

The "MAESTRO system 1.0": a new modelling system for impact studies over complex terrain

To perform realistic impact studies over complex terrain, ATM-PRO s.p.r.l. developed a new 3-D dispersion model, MAESTRO system 1.0*. This system effectively couples a 3-D meso-meteorological model to a Lagrangian dispersion model and runs on a PC at reasonable CPU costs. It takes into account topography and land use. It simulates dry and wet deposition, gravitational settling and plume rise. Validation of the system extends from analytical solution to comparisons with field experiments. The MAESTRO system 1.0 manages multiple sources (punctual, linear, surface or volume) and compounds. It generates classical statistics like annual mean concentration, maxima, percentiles and rolling averages. Moreover, it produces time-series of concentration or deposition over a high density network. This is of paramount importance to enable detection, analysis and understanding of critical situations which depend on emission, meteorology and location. The results obtained for real situations clearly show that topography and meteorology effects on dispersion have to be considered within impact studies over complex terrain.

Intercomparison of two meso-meteorological models applied to the Lisbon region

In this paper two mesoscale meteorological models are applied to the Lisbon region. A special concern is directed to the initial conditions and input parameterization in order to assure that equal simulation constraints were imposed to both models. Results obtained for 4 August 1992 (a typical summer day) are compared to meteorological data acquired in three monitoring stations. Both simulations show similar reactions to the mesoscale forcings that occur in the modelling region. The minor differences found between simulation and reality for the meteorological situation can cause major errors in predicting air quality.

Evaporation from Lake Kinneret: 2. Estimation of the Horizontal variability using a two‐dimensional numerical mesoscale model

The horizontal distribution of evaporation over a small lake surrounded by heterogeneous terrain is quite complex. It is therefore usually not possible to provide accurate evaporation estimates for the whole lake based upon a single observational site, even if this site is located offshore. In the present study, a numerical two‐dimensional terrain‐following mesometeorological model is applied to Lake Kinneret (area of 170 km2, located in northern Israel) to obtain appropriate spatial and temporal resolution of the climatic parameters needed to estimate evaporation. The model is verified by comparing its calculated evaporation rates with those measured at an offshore site by the eddy correlation system and by its ability to reproduce well‐established characteristics of the microclimate over the lake. Results indicate that, for the typical meteorological conditions characterizing the experimental period, a concave horizontal distribution of evaporation rate is predicted across the lake. Consequently, the assumption of a uniform evaporation rate over the whole lake equal to that at the measuring site could lead to a misestimation of the amount of water lost through the evaporative process.

A cold air lake formation in a basin ? a simulation with a mesoscale numerical model

Summary A formation of a cold air lake in a basin is studied with a mesometeorological model. A dynamic Boussinesq hydrostatic mesoscale numerical model is developed in a staggered orthogonal grid with a horizontal resolution of 1 km and with a varying vertical grid. The topography is presented in a block shape so that computation levels are horizontal. The mesometeorological model is tested in three idealized topography cases (a valley, a single mountain, a basin) and test results are discussed. In an alpine basin surrounded by mountains and plateaus the air is supposed to be stagnant at the beginning of the night. Due to differences in radiation cooling an inversion layer is formed in the basin and local wind circulation is studied by model simulations.

On the enhanced smoothing over topography in some mesometeorological models

An equation is derived for the components of the horizontal (turbulent) frictional force in the Σ-coordinate system with special attention to mesometeorological flow models. The starting point is the horizontal equation of motion in its “flux-form” in the Σ-system in which we replace (following Reynolds' procedure) the velocity components u,v and % MathType!MTEF!2!1!+- % feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafq4WdmNbai % aaaaa!37B8! \[ \dot \sigma \] aswell as other relevant quantities by terms of the form u = ū + u′,..., Σ = ±Σ + % MathType!MTEF!2!1!+- % feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafq4WdmNbai % Gbauaaaaa!37C3! \[ \dot \sigma ' \] ′, etc. (ū = time average of u; u′ = fluctuating part of u.) Next, the equation is averaged with respect to time and terms which we believe are small in mesometeorological flows, are neglected. On expressing Σ′ by an appropriate expression that involves w′, the result shows the appearance of two new terms which, have not been considered previously in the published literature. While the expression earlier used in the literature involved the Σ-derivative of % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaaceWG3bGbauaaaaaaaa!380B!\[\overline {u'w'} \] alone, the new terms add the Σ-derivatives of ρα % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaadaahaaWcbeqaaiaaikdaaaaaaaaa!37EC!\[\overline {u'^2 } \] and ρβ % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaaceWG2bGbauaaaaaaaa!380A!\[\overline {u'v'} \] for the x-component of the force, and the Σ-derivatives of ϱβ % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG2bGbauaadaahaaWcbeqaaiaaikdaaaaaaaaa!37ED!\[\overline {v'^2 } \]} and ϱα % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaaceWG2bGbauaaaaaaaa!380A!\[\overline {u'v'} \] for the y-component, where α and β are the slopes of the Σ-surfaces in the x- and y-directions, respectively. Further, a few numerical simulations of the sea-breeze over topography are carried out with and without the correction terms. It is shown that when corrections terms are not included the effective smoothing is stronger above the sloping regions and may amount to as high as 50 percent of the convergence with slopes of ~.04. The inclusion of the new terms does not lead to any special computational difficulties and for that reason there is no compelling reason to neglect them, all the more so because, as is shown, the addition of the new terms results in a consistent apportioning of the ‘degree’ of horizontal diffusion.

Spurious mass loss in some mesometeorological models

The spurious mass losses or gains due to the anelastic continuity equation are assessed, and the implications of this effect are discussed for the case of the simulation of sea breezes.