Correlation Analysis Of The Gas Concentration Field And The Wind Field In The Near-surface Environment

In recent years,with the urbanization and industrialization process,the hazardous gas leakage accidents due to improper operation or equipment malfunction occur frequently.It causes great harm to public safety and the environment.In the space near the ground,the wind is the main danger of the gas diffusion dynamic factors.However,due to the effect of pressure,temperature and other factors and complex terrain,the wind speed and the wind direction show uncertainty and non-stationary strongly.It is caused by the proliferation of dangerous gas concentration is extremely complex.So correlation analysis of the gas concentration field and the wind field in the near-surface environment has important value on the study.For this purpose,complex networks and fractal is used to interpret correlation between the gas concentration field and the wind field.The main works is as follows:1.Superfamily of complex networks are applied to interpret correlation between the gas concentration field and the wind field.The time series of the concentration and the wind field from the different spatial locations are collected and calculated network motif frequency.On this basis,subgraph ratio profile is drawn in order to classify network superfamily.The results show that,the time series of concentration,wind speed and wind direction belong to different superfamily of complex networks.Compared with wind direction,correlation between concentration and speed are stronger.2.Multivariate order-pattern recurrence network are proposed to interpret correlation between the gas concentration field and the wind field.Firstly,using order pattern constructed crossover recursive matrix,it can overcome difficulties of selecting the threshold.Secondly,crossover clustering coefficient of multivariate recurrence network is studied.The coupling direction is found that wind field coupling to the concentration field.Wind speed and concentration signal coupling strength is greater than the coupling strength of the wind and the concentration signal.Then,crossover transitivity of multivariate recurrence network is studied.It is indicated that the cross-connect relationships of wind speed and concentration increased gradually.In contrast,the cross-connect relationships of wind direction and concentration decreased gradually.3.Detrended cross-correlation analysis method based on fractal theory is used to interpret correlation between the gas concentration field and the wind field.It helps us to understand the dynamic evolution of the wind field and the concentration field.The wind rose is selected to determine the upwind and downwind in near-surface environment and the cross-correlation coefficient is studied.We found a power-law distribution of cross-correlation between the wind and the concentration field.Moreover,it is a positive correlation between the wind speed of upwind and the concentration of downwind.It is a negative correlation between the wind direction of upwind and the concentration of downwind.The cross-correlation strength increases with time scales.