Contour diagram fuzzy model for maximum surface ozone prediction

2009 ◽  
Vol 36 (3) ◽  
pp. 6389-6402 ◽  
Author(s):  
Zekai Şen ◽  
Abdüsselam Altunkaynak ◽  
Kadir Alp
Keyword(s):  
Surface Ozone ◽  
Fuzzy Model ◽  
Maximum Surface ◽  
Ozone Prediction ◽  
Contour Diagram

Ozone Prediction Performance of HMM Based on the Data Compressed by Different Wavelet Basis Functions

2012 ◽  
Vol 518-523 ◽  
pp. 1586-1591
Author(s):  
Hao Zhang ◽  
Ze Meng Zhao ◽  
Ahmet Palazoglu ◽  
Wei Sun
Keyword(s):  
Information Content ◽  
Shannon Entropy ◽  
Air Pollutants ◽  
Surface Ozone ◽  
Prediction Performance ◽  
Basis Functions ◽  
Wavelet Basis ◽  
Human Beings ◽  
Ozone Prediction ◽  
Geometric Ratio

Surface ozone in the air boundary layer is one of the most harmful air pollutants produced by photochemical reaction between nitrogen oxides and volatile hydrocarbons, which causes great damage to human beings and environment. The prediction of surface ozone levels plays an important role in the control and the reduction of air pollutants. As model-driven statistical prediction models, hidden Markov Models (HMMs) are rich in mathematical structure and work well in many important applications. Due to the complex structure of HMM, long observation sequences would increase computational load by geometric ratio. In order to reduce training time, wavelet decomposition is used to compress the original observations into shorter ones. During compression step, observation sequences compressed by different wavelet basis functions keep different information content. This may have impact on prediction results. In this paper, ozone prediction performance of HMM based on different wavelet basis functions are discussed. Shannon entropy is employed to measure how much information content is kept in the new sequence compared to the original one. Data from Houston Metropolitan Area, TX are used in this paper. Results show that wavelet basis functions used in data compression step can affect the HMM model performance significantly. The new sequence with the maximum Shannon entropy generates the best prediction result.

scholarly journals Dynamic Adjustment of Climatological Ozone Boundary Conditions for Air-Quality Forecasts

2010 ◽  
Vol 10 (6) ◽  
pp. 13643-13688 ◽  
Author(s):  
P. A. Makar ◽  
W. Gong ◽  
C. Mooney ◽  
J. Zhang ◽  
D. Davignon ◽  
...  
Keyword(s):  
Air Quality ◽  
High Resolution ◽  
Boundary Conditions ◽  
Surface Ozone ◽  
Daily Maximum ◽  
Tropopause Height ◽  
Dynamic Adjustment ◽  
Air Quality Model ◽  
Maximum Surface ◽  
Ozone Profile

Abstract. Ten different approaches for applying lateral and top climatological boundary conditions for ozone have been evaluated using the off-line regional air-quality model AURAMS. All ten approaches employ the same climatological ozone profiles, but differ in the manner in which they are applied, via the inclusion or exclusion of (i) a dynamic adjustment of the climatological ozone profile in response to the model-predicted tropopause height, (ii) a sponge zone for ozone on the model top, (iii) upward extrapolation of the climatological ozone profile, and (iv) different mass consistency corrections. The model performance for each approach was evaluated against North American surface ozone and ozonesonde observations from the BAQS-Met field study period in the summer of 2007. The original daily one-hour maximum surface ozone biases of about +15 ppbv were greatly reduced (halved) in some simulations using alternative methodologies. However, comparisons to ozonesonde observations showed that the reduction in surface ozone bias sometimes came at the cost of significant positive biases in ozone concentrations in the free troposphere and upper troposphere. The best overall performance throughout the troposphere was achieved using a methodology that included dynamic tropopause height adjustment, no sponge zone at the model top, extrapolation of ozone when required above the limit of the climatology, and no mass consistency corrections (global mass conservation was still enforced). The simulation using this model version had a one-hour daily maximum surface ozone bias of +8.6 ppbv, with small reductions in model correlation, and the best comparison to ozonesonde profiles. This recommended and original methodologies were compared for two further case studies: a high-resolution simulation of the BAQS-Met measurement intensive, and a study of the downwind region of the Canadian Rockies. Significant improvements were noted for the high resolution simulations during the BAQS-Met measurement intensive period, both in formal statistical comparisons and time series comparisons of events at surface stations. The tests for the downwind-Rockies region showed that the coupling between vertical transport associated with troposphere/stratosphere exchange, and that associated with boundary layer turbulent mixing, may contribute to ozone positive biases.

Statistical modeling of daily maximum surface ozone concentrations

2010 ◽  
Vol 23 (4) ◽  
pp. 284-292 ◽  
Author(s):  
A. M. Zvyagintsev ◽  
I. B. Belikov ◽  
N. F. Elanskii ◽  
G. Kakadzhanova ◽  
I. N. Kuznetsova ◽  
...  
Keyword(s):  
Statistical Modeling ◽  
Surface Ozone ◽  
Daily Maximum ◽  
Maximum Surface ◽  
Ozone Concentrations

scholarly journals Development and evaluation of the Screening Trajectory Ozone Prediction System (STOPS, version 1.0)

2015 ◽  
Vol 8 (5) ◽  
pp. 1383-1394 ◽  
Author(s):  
B. H. Czader ◽  
P. Percell ◽  
D. Byun ◽  
S. Kim ◽  
Y. Choi
Keyword(s):  
Boundary Conditions ◽  
Initial Conditions ◽  
Surface Ozone ◽  
Prediction System ◽  
Atmospheric Conditions ◽  
Detailed Chemistry ◽  
Mixing Ratios ◽  
Ozone Prediction ◽  
The Mean ◽  
Simulation Results

Abstract. A hybrid Lagrangian–Eulerian based modeling tool has been developed using the Eulerian framework of the Community Multiscale Air Quality (CMAQ) model. It is a moving nest that utilizes saved original CMAQ simulation results to provide boundary conditions, initial conditions, as well as emissions and meteorological parameters necessary for a simulation. Given that these files are available, this tool can run independently of the CMAQ whole domain simulation, and it is designed to simulate source–receptor relationships upon changes in emissions. In this tool, the original CMAQ's horizontal domain is reduced to a small sub-domain that follows a trajectory defined by the mean mixed-layer wind. It has the same vertical structure and physical and chemical interactions as CMAQ except advection calculation. The advantage of this tool compared to other Lagrangian models is its capability of utilizing realistic boundary conditions that change with space and time as well as detailed chemistry treatment. The correctness of the algorithms and the overall performance was evaluated against CMAQ simulation results. Its performance depends on the atmospheric conditions occurring during the simulation period, with the comparisons being most similar to CMAQ results under uniform wind conditions. The mean bias for surface ozone mixing ratios varies between −0.03 and −0.78 ppbV and the slope is between 0.99 and 1.01 for different analyzed cases. For complicated meteorological conditions, such as wind circulation, the simulated mixing ratios deviate from CMAQ values as a result of the Lagrangian approach of using mean wind for its movement, but are still close, with the mean bias for ozone varying between 0.07 and −4.29 ppbV and the slope varying between 0.95 and 1.06 for different analyzed cases. For historical reasons, this hybrid Lagrangian–Eulerian based tool is named the Screening Trajectory Ozone Prediction System (STOPS), but its use is not limited to ozone prediction as, similarly to CMAQ, it can simulate concentrations of many species, including particulate matter and some toxic compounds, such as formaldehyde and 1,3-butadiene.

scholarly journals Dynamic adjustment of climatological ozone boundary conditions for air-quality forecasts

2010 ◽  
Vol 10 (18) ◽  
pp. 8997-9015 ◽  
Author(s):  
P. A. Makar ◽  
W. Gong ◽  
C. Mooney ◽  
J. Zhang ◽  
D. Davignon ◽  
...  
Keyword(s):  
Air Quality ◽  
High Resolution ◽  
Boundary Conditions ◽  
Surface Ozone ◽  
Daily Maximum ◽  
Tropopause Height ◽  
Dynamic Adjustment ◽  
Air Quality Model ◽  
Maximum Surface ◽  
Ozone Profile

Abstract. Ten different approaches for applying lateral and top climatological boundary conditions for ozone have been evaluated using the off-line regional air-quality model AURAMS, driven with meteorology provided by the GEM weather-forecast model. All ten approaches employ the same climatological ozone profiles, but differ in the manner in which they are applied, via the inclusion or exclusion of (i) a dynamic adjustment of the climatological ozone profile in response to the model-predicted tropopause height, (ii) a sponge zone for ozone on the model top, (iii) upward extrapolation of the climatological ozone profile, and (iv) different mass consistency corrections. The model performance for each approach was evaluated against North American surface ozone and ozonesonde observations from the BAQS-Met field study period in the summer of 2007. The original daily one-hour maximum surface ozone biases of about +15 ppbv were greatly reduced (halved) in some simulations using alternative methodologies. However, comparisons to ozonesonde observations showed that the reduction in surface ozone bias sometimes came at the cost of significant positive biases in ozone concentrations in the free troposphere and upper troposphere. The best overall performance throughout the troposphere was achieved using a methodology that included dynamic tropopause height adjustment, no sponge zone at the model top, extrapolation of ozone when required above the limit of the climatology, and no mass consistency corrections (global mass conservation was still enforced). The simulation using this model version had a one-hour daily maximum surface ozone bias of +8.6 ppbv, with small reductions in model correlation, and the best comparison to ozonesonde profiles. This recommended and original methodologies were compared for two further case studies: a high-resolution simulation of the BAQS-Met measurement intensive, and a study of the downwind region of the Canadian Rockies. Significant improvements were noted for the high resolution simulations during the BAQS-Met measurement intensive period, both in formal statistical comparisons and time series comparisons of events at surface stations. The tests for the downwind-Rockies region showed that the coupling between vertical transport associated with troposphere/stratosphere exchange, and that associated with boundary layer turbulent mixing, may contribute to ozone positive biases. The results may be unique to the modelling setup employed, but the results also highlight the importance of evaluating boundary condition and mass consistency/correction algorithms against three-dimensional datasets.

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