The continuous nineteen-year time series of the data of daily observations of the submicron aerosol mass concentration M is analyzed. Some stable peculiarities of the intra-annual behavior of this parameter, smoothed by means of the moving average, are revealed. In two thirds of the intra-annual courses (12 years), high-frequency variations of M with periods 3-20 days are modulated by quasi-oscillatory processes reproducing from year to year. They are two peaks in M content in January-May with approximately equal duration of about 70 days, separated by a deep dip. Further, another deep dip of the M value follows with the same duration of ten weeks, and finally approximately from the end of August, one or two less pronounced peaks are observed. As for two other possible scenarios, their repeatability is less, and in the first one, two winter-spring peaks merge into wide one, and the February peak is missing in the second one.
submicron aerosol, mass concentration, intra-annual variations