Calculation
The programs are based on the SYMOS'97 methodology, which is designed primarily for scattering studies as a basis for assessing air quality.
The values of the calculated concentrations at the reference point depend inter alia on the shape of the terrain between source and reference point. For calculation, the terrain enters the form of the altium value matrix in desired regions of any cell size.The calculation may include the effect of canting at small distances because in a number of cases it is necessary to calculate the pollution even at small distances from the chimney where the siding does not reach yet of its maximum height. The methodology includes the shape of the curve, after which the exhalations rise, and thus calculate concentrations even at a very small distance from the source. If there are several chimneys close together so that their smoke sidings can interact with each other, the total cant the siding grows. The calculation model includes relationships to calculate this increase.
The program also includes weakening the impact of low sources on air pollution in the mountains because in the atmosphere there are retaining layers above which pollution from low sources can not get. The model contains relationships expressing the statistical frequency of occurrence of the upper limit of inversion derived from aerological measurements temperature air layer and 850 hPa at the meteorological station Praha-Libuš.
For the calculation of annual averages, the relative annual utilization of the maximum is also given for each source performance.
In the case where the terrain is elevated between the source and the reference point, it is assumed that the smoke siding protrudes along
uphill slopes and the effective chimney height correction is used. Pollutants are different in the atmosphere
processes that are eliminated from the atmosphere. These are either chemical or physical processes.
Physical processes are further divided into wet and dry deposition, according to the manner in which the impurities
removed.
Dry deposition: is the capture of gaseous or solid matter on the Earth's surface.
Wet deposition: is the uptake of these substances by falling precipitation.
Category of pollutants
The model considers the average residence time of the substance in the atmosphere, which can be determined for a number of substances. For the first the approach is divided into three categories and the resulting concentration is calculated by including correction for deposition a transformation according to given relationships for the given pollutant category. The individual pollutants are divided into categories according to the average residence time in the atmosphere.- Cat. I - 20 hoursn
- Cat. II - 6 days
- Cat. III - 2 years
Calculation of concentrations from surface sources
The surface source is divided into a sufficient number of square surface elements. Element size is selected depending on the size at the distance of the nearest reference point.Calculation of concentrations from line sources
As with planar sources, we calculate the concentration from the line source by dividing the line source into sufficient number of length elements.Note: Linear sources are mainly automobile roads.
Calculation of average annual concentrations
- it is necessary to construct a detailed wind rose, ie to determine the wind direction frequency for each azimuth from 0 ° to 359 ° for all stability classes and wind speed classes. The input wind roset contains the relative percentages for 8 basic wind directions and windless rates in all stability classes.
- The program allows you to perform calculations not only after 1 ° (preset), but also in the range from 0.5 ° to 5 °.
Climate input data
Climate input data usually refers to a one-year period. Attention should be paid to whether data from that meteorological or climatic station representative of the place of calculation. Assess this representativeness is a matter of a lot complicated, depends not only on terrain topography and station distance from the place of calculation, but also to the type of climatic data.As the most important climatic input, the rosette is differentiated according to wind speed and temperature stability of the atmosphere.
Wind speed
are divided into three speed classes:- light wind 1.7 m/s
- medium wind 5 m/s
- strong wind 11 m/s
Temperature stability of the atmosphere
its measure is a vertical temperature gradient describing its temperature layer. The Stability Classification contains five of air stability classes:- superstabil - strong inversions, very poor scattering conditions
- stabil - common inversions, poor scattering conditions
- izotermn - weak inversions, isothermia or a small positive temperature gradient often occurring mildly impaired dispersion conditions
- normal - indifferent temperature coating, a common case of good scattering conditions
- labile - labile temperature coating, rapid dispersion of pollutants.
Related
| Calculating | A brief description of the program section |
|---|---|
| SYMOS'97 | Product description |
| WindRose | WindRose rotation for the JTSK system |