Contribution of Inversion Management to Controlling the Threshold of Urban Air Quality Index (Case Study: Isfahan City)

Introduction
Air inversion is a climatic phenomenon causing increases in the aggregation of pollutants in highly populated and industrial cities. Hence, changes exceeding the air quality threshold would have extensive problems for the citizens. Attention of managers to this problem is mainly referred to as polluting factors. However, in case this phenomenon exists during all the seasons and as the polluting factors have no great changes during the year, some factors can lead to exceed the air quality index from the threshold value. Hence, there can be an approach for reducing the continuity of this situation, if continuity of the inversion leads to such a condition.
The main problem in this study is whether there is the possibility of managing Esfahan air pollution in such a way for to prevent atmospheric pollution density to reach the critical threshold. Therefore, we try to find a model to control the air pollution crisis threshold by relying on the climatic management.
Materials and methods
The research method of this study is mainly relying on an analytical method and dependent on the principles of interpreting the data of climatic and atmospheric pollutants. The subject of air pollution critical thresholds is considered for analysis of the research purposes. Thus, these data are related to a 30-year statistics (1985-2015) from Meteorological Organization and balloon data including pressure, temperature, speed, wind direction, and rains, and the air pollution data from 14 pollution measurement stations belonging to Esfahan Environmental Organization. The analyses in various levels enabled us to find out the inversion conditions in different levels. Hence, only the levels of 1670, 1680, and 1860 m were selected due to formation of pressure and temperature among one hundred weather maps. Then, the cellular excitation index (C.E.=f/k) was calculated, where k=    and “f” is the Newton mass and the temperature and cellular pressure differences. The two indices showed the conditions and possibility of excitation of temperature and pressure closed cells for reducing the continuity of inversion time.
Results and discussion
Given the documentation data and extracted results, we have determined the inversion in the city of Esfahan in terms of the intensity, continuity, and altitude of the inversion in various levels. Thus, the temperature and pressure inversion conditions were investigated for different levels with regards to the balloon data. The inversion analysis for different levels became possible according to temperature and pressure closed cells. The analyses included 100 maps from different altitudes. According to the analysis results, two levels of 1670 m and 1680 m were for the temperature and the level of 1860 m was for the pressure in the closed cells. In fact, the above altitudes were the levels with temperature and pressure cells with the specific differences providing the possibility of excitation. The excitation conditions were finally calculated by the cellular excitation index. Threshold control models for November, December, and January in multiple basis are as follows:
- General model for November includes:
A.P.C^*_isf.Nov = (C.M^**) V (U.M^***)
A.P.C_isf.Nov = (C.E^****) V (C.CO or C.SO2)
A.P.C_isf.Nov = (C.E) V (C.NO2 or C.O3)
*Air Pollution Control
** Climatic Management
*** Urban Management
**** Cell Excitability
- General model for December includes:
A.P.C_isf.Dec = (C.M) V (U.M)
A.P.C_isf.Dec = (C.E) V (C.CO or C.SO2)
A.P.C_isf.Dec = (C.E) V (C.NO2 or C.O3)
- General model for January includes:
A.P.C_isf.Jan = (C.M) V (U.M)
A.P.C_isf.Jan = (C.E) V (C.CO or C.SO2)
A.P.C_isf.Jan = (C.E) V (C.NO2 or C.O3)
Conclusion
Statistical analysis of the obtained information from the balloons and atmospheric profile indicate that the inversion phenomenon in Esfahan occurs in different days of the year. In other words, inversion phenomenon may not be considered as the main factor in emergence of pollution crisis, but its continuity in the condition is a factor for increasing the density of atmospheric pollutants to exceed the critical threshold (AQI 150). Hence, it can be stated that continuity of inversion condition can force the concentration of pollutants to exceed the permissible range.      
It can be concluded from the statement that occurrence of atmospheric pollution condition can be prevented by two different methods: (1) reducing inversion continuity, (2) management of urban pollutants. Thus, the following statements can be considered as the achievements of this study:

In the most intensive dominating days of air inversion, pressure and temperature cellular nuclei provide the possibility to manage the continuity duration of air inversion by exciting the cells,
Regarding the intensity of inversion phenomenon exceeding quality index from the permissible range can be avoided in November and December by controlling the inter-city traffic control, and in January by controlling the industrial pollutants.