Influence of air temperature on air composition in Moscow

Abstract

Empirical relations between T and surface concentrations of CO2 and five minor air gases have been studied on a base of hourly data during 12 years. In wide range -6…+15 °C significant changes of minor gases are absent. Real tendencies are increase of O3 and, vice versa, fall of NO and NO2 with increasing T from +15.+17 to +38 °C. Both effects are a consequence of unstable stratification that enhances vertical mixing. In cool weather -7.-18 °C O3 falls whereas nitrogen oxides grow with decreasing T due to frequent inversions and slowing down the NO oxidation rate. At an even lower temperature up to -30 °C NO and NO2, vice versa, decrease with decreasing T – probably, due to strong cold advection of clean Arctic air. Unlike minor gases, CO2 decreases with increasing T up to 25 °C due to photosynthesis intensification from winter to summer. Seeming growth of CO at T>27 °C is fully explained by smoky haze during heat waves in 2010 and 2002. The CO2 growth in hot weather is also created by heat stress of trees. Thus, except only oxidation rate, any influence of T is indirect as a result of stratification, photosynthesis, smoky haze, advection, etc.