Influences of initial conditions and boundary conditions on regional and urban scale Eulerian air quality transport model simulations

Abstract. Source apportionment modeling provides valuable information on the contributions of different source sectors and/or source regions to ozone (O3) or fine particulate matter (PM2.5) concentrations. This information can be useful in designing air quality management strategies and in understanding the potential benefits of reducing emissions from a particular source category. The Comprehensive Air quality Model with Extensions (CAMx) offers unique source attribution tools, called the Ozone and Particulate Source Apportionment Technology (OSAT/PSAT), which track source contributions. We present results from a CAMx source attribution modeling study for a summer month and a winter month using a recently evaluated European CAMx modeling database developed for Phase 3 of the Air Quality Model Evaluation International Initiative (AQMEII). The contributions of several source sectors (including model boundary conditions of chemical species representing transport of emissions from outside the modeling domain as well as initial conditions of these species) to O3 or PM2.5 concentrations in Europe were calculated using OSAT and PSAT, respectively. A 1-week spin-up period was used to reduce the influence of initial conditions. Evaluation focused on 16 major cities and on identifying source sectors that contributed above 5 %. Boundary conditions have a large impact on summer and winter ozone in Europe and on summer PM2.5, but they are only a minor contributor to winter PM2.5. Biogenic emissions are important for summer ozone and PM2.5. The important anthropogenic sectors for summer ozone are transportation (both on-road and non-road), energy production and conversion, and industry. In two of the 16 cities, solvent and product also contributed above 5 % to summertime ozone. For summertime PM2.5, the important anthropogenic source sectors are energy, transportation, industry, and agriculture. Residential wood combustion is an important anthropogenic sector in winter for PM2.5 over most of Europe, with larger contributions in central and eastern Europe and the Nordic cities. Other anthropogenic sectors with large contributions to wintertime PM2.5 include energy, transportation, and agriculture.

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The impact of multi-species surface chemical observations assimilation on the air quality forecasts in China

10.5194/acp-2018-768 ◽

2018 ◽

Author(s):

Zhen Peng ◽

Lili Lei ◽

Zhiquan Liu ◽

Jianning Sun ◽

Aijun Ding ◽

...

Keyword(s):

Air Quality ◽

Transport Model ◽

Initial Conditions ◽

Yangtze River Delta ◽

River Delta ◽

Chemical Transport Model ◽

The North ◽

Surface Measurements ◽

Haze Episode ◽

The Impact

Abstract. An Ensemble Kalman Filter data assimilation (DA) system has been developed to improve air quality forecasts using surface measurements of PM10, PM2.5, SO2, NO2, O3 and CO together with an online regional chemical transport model, WRF-Chem (Weather Research and Forecasting with Chemistry). This DA system was applied to simultaneously adjust the chemical initial conditions (ICs) and emission inputs of the species affecting PM10, PM2.5, SO2, NO2, O3 and CO concentrations during an extreme haze episode that occurred in early October 2014 over the North China Plain. Numerical experimental results indicate that ICs play key roles in PM2.5, PM10 and CO forecasts during the severe haze episode. The 72-h verification forecasts with the optimized ICs and emissions performed very similarly to the verification forecasts with only optimized ICs and the prescribed emissions. For the first-day forecast, near perfect verification forecasts results were achieved. However, with longer range forecasts, the DA impacts decayed quickly. For the SO2 verification forecasts, it was efficient to improve the SO2 forecast via the joint adjustment of SO2 ICs and emissions. Large improvements were achieved for SO2 forecasts with both the optimized ICs and emissions for the whole 72-h forecast range. Similar improvements were achieved for SO2 forecasts with optimized ICs only for just the first 3 h, and then the impact of the ICs decayed quickly. For the NO2 verification forecasts, both forecasts performed much worse than the control run without DA. Plus, the 72-h O3 verification forecasts performed worse than the control run during the daytime, due to the worse performance of the NO2 forecasts, even though they performed better at night. However, relatively favorable NO2 and O3 forecast results were achieved for the Yangtze River delta and Pearl River delta regions.

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Assimilation of OMI NO<sub>2</sub> retrievals into the limited-area chemistry-transport model DEHM (V2009.0) with a 3-D OI algorithm

Geoscientific Model Development ◽

10.5194/gmd-6-1-2013 ◽

2013 ◽

Vol 6 (1) ◽

pp. 1-16 ◽

Cited By ~ 17

Author(s):

J. D. Silver ◽

J. Brandt ◽

M. Hvidberg ◽

J. Frydendall ◽

J. H. Christensen

Keyword(s):

Air Quality ◽

Data Assimilation ◽

Transport Model ◽

Initial Conditions ◽

Three Dimensional ◽

Optimal Interpolation ◽

Limited Area ◽

Background Error ◽

Geophysical Field ◽

Chemistry Transport Model

Abstract. Data assimilation is the process of combining real-world observations with a modelled geophysical field. The increasing abundance of satellite retrievals of atmospheric trace gases makes chemical data assimilation an increasingly viable method for deriving more accurate analysed fields and initial conditions for air quality forecasts. We implemented a three-dimensional optimal interpolation (OI) scheme to assimilate retrievals of NO2 tropospheric columns from the Ozone Monitoring Instrument into the Danish Eulerian Hemispheric Model (DEHM, version V2009.0), a three-dimensional, regional-scale, offline chemistry-transport model. The background error covariance matrix, B, was estimated based on differences in the NO2 concentration field between paired simulations using different meteorological inputs. Background error correlations were modelled as non-separable, horizontally homogeneous and isotropic. Parameters were estimated for each month and for each hour to allow for seasonal and diurnal patterns in NO2 concentrations. Three experiments were run to compare the effects of observation thinning and the choice of observation errors. Model performance was assessed by comparing the analysed fields to an independent set of observations: ground-based measurements from European air-quality monitoring stations. The analysed NO2 and O3 concentrations were more accurate than those from a reference simulation without assimilation, with increased temporal correlation for both species. Thinning of satellite data and the use of constant observation errors yielded a better balance between the observed increments and the prescribed error covariances, with no appreciable degradation in the surface concentrations due to the observation thinning. Forecasts were also considered and these showed rather limited influence from the initial conditions once the effects of the diurnal cycle are accounted for. The simple OI scheme was effective and computationally feasible in this context, where only a single species was assimilated, adjusting the three-dimensional field for this compound. Limitations of the assimilation scheme are discussed.

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On the influence of chemical initial and boundary conditions on annual regional air quality model simulations for North America

Atmospheric Environment ◽

10.1016/j.atmosenv.2009.07.019 ◽

2009 ◽

Vol 43 (32) ◽

pp. 4873-4885 ◽

Cited By ~ 25

Author(s):

Mehrez Samaali ◽

Michael D. Moran ◽

Véronique S. Bouchet ◽

Radenko Pavlovic ◽

Sophie Cousineau ◽

...

Keyword(s):

Air Quality ◽

North America ◽

Boundary Conditions ◽

Air Quality Model ◽

Quality Model ◽

Model Simulations ◽

Regional Air Quality ◽

Initial And Boundary Conditions

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The impact of multi-species surface chemical observation assimilation on air quality forecasts in China

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-17387-2018 ◽

2018 ◽

Vol 18 (23) ◽

pp. 17387-17404 ◽

Cited By ~ 10

Author(s):

Zhen Peng ◽

Lili Lei ◽

Zhiquan Liu ◽

Jianning Sun ◽

Aijun Ding ◽

...

Keyword(s):

Air Quality ◽

Transport Model ◽

Initial Conditions ◽

Yangtze River Delta ◽

River Delta ◽

Chemical Transport Model ◽

The North ◽

Surface Measurements ◽

Haze Episode ◽

The Impact

Abstract. An ensemble Kalman filter data assimilation (DA) system has been developed to improve air quality forecasts using surface measurements of PM10, PM2.5, SO2, NO2, O3, and CO together with an online regional chemical transport model, WRF-Chem (Weather Research and Forecasting with Chemistry). This DA system was applied to simultaneously adjust the chemical initial conditions (ICs) and emission inputs of the species affecting PM10, PM2.5, SO2, NO2, O3, and CO concentrations during an extreme haze episode that occurred in early October 2014 over East Asia. Numerical experimental results indicate that ICs played key roles in PM2.5, PM10 and CO forecasts during the severe haze episode over the North China Plain. The 72 h verification forecasts with the optimized ICs and emissions performed very similarly to the verification forecasts with only optimized ICs and the prescribed emissions. For the first-day forecast, near-perfect verification forecasts results were achieved. However, with longer-range forecasts, the DA impacts decayed quickly. For the SO2 verification forecasts, it was efficient to improve the SO2 forecast via the joint adjustment of SO2 ICs and emissions. Large improvements were achieved for SO2 forecasts with both the optimized ICs and emissions for the whole 72 h forecast range. Similar improvements were achieved for SO2 forecasts with optimized ICs only for the first 3 h, and then the impact of the ICs decayed quickly. For the NO2 verification forecasts, both forecasts performed much worse than the control run without DA. Plus, the 72 h O3 verification forecasts performed worse than the control run during the daytime, due to the worse performance of the NO2 forecasts, even though they performed better at night. However, relatively favorable NO2 and O3 forecast results were achieved for the Yangtze River delta and Pearl River delta regions.

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DYNAMICS OF THERMAL LOSSES BY CONVECTION AND RADIATION OF THE SPHERICAL HEAT ACCUMULATOR OF SOLAR PLANTS

Elektrotekhnologii i elektrooborudovanie v APK ◽

10.22314/2658-4859-2020-67-4-57-62 ◽

2020 ◽

Vol 4 (41) ◽

pp. 57-62

Author(s):

SHAVKAT KLYCHEV ◽

◽

BAKHRAMOV SAGDULLA ◽

VALERIY KHARCHENKO ◽

VLADIMIR PANCHENKO ◽

...

Keyword(s):

Boundary Conditions ◽

Heat Loss ◽

Initial Conditions ◽

Water System ◽

Heat Losses ◽

Research Purpose ◽

Heat Accumulator ◽

Water Heaters ◽

Intrinsic Radiation ◽

Over Time

There are needed energy (heat) accumulators to increase the efficiency of solar installations, including solar collectors (water heaters, air heaters, dryers). One of the tasks of designing heat accumulators is to ensure its minimal heat loss. The article considers the problem of determining the distribution of temperatures and heat losses by convection and radiation of the heat insulation-accumulating body (water) system for a ball heat accumulator under symmetric boundary conditions. The problem is solved numerically according to the program developed on the basis of the proposed «gap method». (Research purpose) The research purpose is in determining heat losses by convection and radiation of a two-layer ball heat accumulator with symmetric boundary conditions. (Materials and methods) Authors used the Fourier heat equation for spherical bodies. The article presents the determined boundary and initial conditions for bodies and their surfaces. (Results and discussion) The thickness of the insulation and the volume of the heat accumulator affect the dynamics and values of heat loss. The effect of increasing the thickness of the thermal insulation decreases with increasing its thickness, starting with a certain volume of the heat accumulator or with R > 0.3 meters, the heat losses change almost linearly over time. The dynamics of heat loss decreases with increasing shelf life, but the losses remain large. (Conclusions) Authors have developed a method and program for numerical calculation of heat loss and temperature over time in a spherical two-layer heat accumulator with symmetric boundary conditions, taking into account both falling and intrinsic radiation. The proposed method allows to unify the boundary conditions between contacting bodies.

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AN ASSEMBLY OF PRESCRIBED BOUNDARY CONDITIONS FOR THE CLIMATE-MODEL SIMULATIONS ACROSS THE PERMO-TRIASSIC BOUNDARY(PTB)

10.1130/abs/2020sc-343389 ◽

2020 ◽

Author(s):

Mitali D. Gautam ◽

◽

Arne Winguth ◽

Cornelia Winguth ◽

Christopher Scotese ◽

...

Keyword(s):

Boundary Conditions ◽

Climate Model ◽

Triassic Boundary ◽

Model Simulations ◽

Climate Model Simulations

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Urban Air Quality Modeling Using Low-Cost Sensor Network and Data Assimilation in the Aburrá Valley, Colombia

Atmosphere ◽

10.3390/atmos12010091 ◽

2021 ◽

Vol 12 (1) ◽

pp. 91

Author(s):

Santiago Lopez-Restrepo ◽

Andres Yarce ◽

Nicolás Pinel ◽

O.L. Quintero ◽

Arjo Segers ◽

...

Keyword(s):

Air Quality ◽

Data Assimilation ◽

Transport Model ◽

Cost Model ◽

Low Cost ◽

Model Performance ◽

Monitoring Network ◽

Correlation Factor ◽

Chemical Transport Model ◽

High Quality

The use of low air quality networks has been increasing in recent years to study urban pollution dynamics. Here we show the evaluation of the operational Aburrá Valley’s low-cost network against the official monitoring network. The results show that the PM2.5 low-cost measurements are very close to those observed by the official network. Additionally, the low-cost allows a higher spatial representation of the concentrations across the valley. We integrate low-cost observations with the chemical transport model Long Term Ozone Simulation-European Operational Smog (LOTOS-EUROS) using data assimilation. Two different configurations of the low-cost network were assimilated: using the whole low-cost network (255 sensors), and a high-quality selection using just the sensors with a correlation factor greater than 0.8 with respect to the official network (115 sensors). The official stations were also assimilated to compare the more dense low-cost network’s impact on the model performance. Both simulations assimilating the low-cost model outperform the model without assimilation and assimilating the official network. The capability to issue warnings for pollution events is also improved by assimilating the low-cost network with respect to the other simulations. Finally, the simulation using the high-quality configuration has lower error values than using the complete low-cost network, showing that it is essential to consider the quality and location and not just the total number of sensors. Our results suggest that with the current advance in low-cost sensors, it is possible to improve model performance with low-cost network data assimilation.

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The Environmental Effects of the April 2020 Wildfires and the Cs-137 Re-Suspension in the Chernobyl Exclusion Zone: A Multi-Hazard Threat

Atmosphere ◽

10.3390/atmos12040467 ◽

2021 ◽

Vol 12 (4) ◽

pp. 467

Author(s):

Rocío Baró ◽

Christian Maurer ◽

Jerome Brioude ◽

Delia Arnold ◽

Marcus Hirtl

Keyword(s):

Air Quality ◽

Nuclear Power ◽

Transport Model ◽

Atmospheric Transport ◽

Point Of View ◽

Plume Dispersion ◽

Exclusion Zone ◽

Fire Plume ◽

Mean Values ◽

The Impact

This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of April 2020 in and around the highly contaminated Chernobyl Exclusion Zone (CEZ). Due to the critical fire location, concerns arose about secondary radioactive contamination potentially spreading over Europe. The impact of the fire was assessed through the evaluation of fire plume dispersion and re-suspension of the radionuclide Cs-137, whereas, to assess the smoke plume effect, a WRF-Chem simulation was performed and compared to Tropospheric Monitoring Instrument (TROPOMI) satellite columns. The results show agreement of the simulated black carbon and carbon monoxide plumes with the plumes as observed by TROPOMI, where pollutants were also transported to Belarus. From an air quality and health perspective, the wildfires caused extremely bad air quality over Kiev, where the WRF-Chem model simulated mean values of PM2.5 up to 300 µg/m3 (during the first fire outbreak) over CEZ. The re-suspension of Cs-137 was assessed by a Bayesian inverse modelling approach using FLEXPART as the atmospheric transport model and Ukraine observations, yielding a total release of 600 ± 200 GBq. The increase in both smoke and Cs-137 emissions was only well correlated on the 9 April, likely related to a shift of the focus area of the fires. From a radiological point of view even the highest Cs-137 values (average measured or modelled air concentrations and modelled deposition) at the measurement site closest to the Chernobyl Nuclear Power Plant, i.e., Kiev, posed no health risk.

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Solving nonlinear third-order three-point boundary value problems by boundary shape functions methods

Advances in Difference Equations ◽

10.1186/s13662-021-03288-x ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Ji Lin ◽

Yuhui Zhang ◽

Chein-Shan Liu

Keyword(s):

Boundary Conditions ◽

Boundary Value Problems ◽

Initial Conditions ◽

Boundary Value ◽

Accurate Solution ◽

Point Boundary ◽

Third Order ◽

Boundary Shape ◽

Free Function ◽

New Algorithms

AbstractFor nonlinear third-order three-point boundary value problems (BVPs), we develop two algorithms to find solutions, which automatically satisfy the specified three-point boundary conditions. We construct a boundary shape function (BSF), which is designed to automatically satisfy the boundary conditions and can be employed to develop new algorithms by assigning two different roles of free function in the BSF. In the first algorithm, we let the free functions be complete functions and the BSFs be the new bases of the solution, which not only satisfy the boundary conditions automatically, but also can be used to find solution by a collocation technique. In the second algorithm, we let the BSF be the solution of the BVP and the free function be another new variable, such that we can transform the BVP to a corresponding initial value problem for the new variable, whose initial conditions are given arbitrarily and terminal values are determined by iterations; hence, we can quickly find very accurate solution of nonlinear third-order three-point BVP through a few iterations. Numerical examples confirm the performance of the new algorithms.

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