Effect of NO2 on O3 Using Complex Network Topology Analysis

In order to study the variation law of the influence degree of air quality factors under time series, this article selects the hourly concentration values of NO
₂
and O
₃
from November 2017 to October 2018 in Lanzhou city as the research object, and based on the coarse granulation method, NO
₂
and O
₃
. The correlation value of hourly concentration value is transformed into the influence degree symbol, and the sequence of effect degree variation under time series is obtained. The network model is constructed by using complex network theory to analyze the time series of NO
₂
and O
₃
influence degree series, and the differences and changes in network topology characteristics in overall and different season effect degree symbols of Lanzhou are analyzed. The results show the following. First, from the network analysis, the number of negative correlations of NO
₂
to O
₃
is far greater than that of positive correlation and basic noncorrelation effect degree, indicating that NO
₂
and O
₃
are negatively correlated. From the factor of season, the law of negative correlation is summer > autumn > spring > winter, indicating that light and temperature are the main factors for the conversion of NO
₂
to O
₃
. Second, through the analysis of Lanzhou's overall and seasonal related network topological features, such as node degree distribution, node intensity distribution, and network betweenness, the change sequence consisting of the influence degree symbols h, H, and m plays an important role in each network. The sequence of changes consisting of M, H, and S has the lowest effect in each network, indicating that in the day of the time series, the conversion of NO
₂
to O
₃
in Lanzhou is mainly dominated by different degrees of negative correlation. Third, through the analysis of network cluster degree, it is found that most of the changes in the degree of change have a transformation and a high degree of transformation, indicating that the effect of NO
₂
on O
₃
in the original sequence is less stable. Fourth, through the network average shortest path and diameter analysis, it is found that the conversion between the changes in the degree of influence requires at least one day and at most three days. That is to say, the influence of NO
₂
on O
₃
can be maintained for up to three days. From the network, the complexity of the influence of NO
₂
on O
₃
in the original sequence of four seasons was founded.