Seasonal variability of diurnal behavior of concentrations of submicron aerosol and absorbing substance in coordinates of sun elevation

摘要

Main regularities of the normalized (to the daily mean values) diurnal behaviors of the concentrations of the aerosol dry matter and soot (black carbon, BC) in the near-ground air layer in Siberia are revealed on the basis of long-term measurements at the aerosol monitoring station of IAO SB RAS. It is revealed that the diurnal behavior at radiative type of weather is the same in all seasons and contains morning and evening maximums and nighttime and daytime minimums. The positions of maximums in the diurnal behaviors and their amplitudes show stable seasonal variability which is observed as approaching of the maximums in winter (9-11 a.m. and 8 p.m.) and their moving from each other in summer (7-9 a.m. and 10-11 p.m.). The differences in diurnal behaviors of aerosol and soot lie in the fact that the morning maximum of the concentration of soot is better pronounced than aerosol in all seasons. These signs are evidence of some independence of diurnal dynamics of BC and submicron aerosol. A new approach is proposed and tested for description of the diurnal behaviors of the aerosol characteristics as functions of a parameter related with solar radiation. It is shown that the normalized sun elevation as such parameter is effective for analysis of the structure of diurnal behavior. The extremes of the diurnal behavior are closely related with the characteristic values of the normalized sun elevation. Statistically significant decrease of the daily mean variation coefficients of aerosol and soot occurs is all seasons in the sun related coordinates. The greatest changes are observed in spring and autumn (up to 6%). It provides for some promises for decreasing the errors in parameterization of the diurnal behaviors of the concentrations of aerosol and soot.