annual minimum
2.The inter-annual change of precipitation was analyzed through the ratio of maximum and minimum precipitation.
9.The results indicated that the average value of the mass annual concentration of OC and EC was 60.84 μg/m3 and 11.51 μg/m3, respectively. The ratio of OC and EC exceeded 2.0, which revealed serious secondary pollution in Chongqing. The maximum and minimum of OC appeared in autumn, summer, respectively.

