Study on surface O3 chemistry and photochemistry by UV energy conservation

AbstractThe point of view of transmission and conservation of UV energy was put forward to study O3 photochemical processes. Surface O3, NOX, UV radiation and meteorological parameters were monitored at three sites. An energy relationship between O3 and its affecting factors (NOX, photochemistry, scattering, UV radiation) was built, and used to analyze O3 and its relations with all factors. The calculated hourly and daily O3 agreed well with that observed under different sky conditions and at different sites. The interactions between O3 and its factors were analyzed, and it was found that UV is an important energy to trigger O3 chemical and photochemical (C&P) reactions in the atmosphere, and 1 hour is a suitable time for UV energy transfer and utilization. The important roles of main factors to O3 in clear and all skies were investigated and NO term was found to be more important than NO2 term for the contribution to O3. Direct and indirect UV energy (including chemical energy) utilization by NO, NO2, and other constituents in the atmosphere control the formation and destruction of O3. The photochemical term is an important bridge to relate O3 C&P processes and UV absorption. The sensitivity studies showed that O3 is more sensitive to its precursors than the other factors, and more sensitive to NO2 than NO in summer. The responses of O3 to the changes of all affecting factors are higher in summer than in autumn and higher in clear sky compared to cloudy sky conditions