Some connections between aerosols, atmospheric transport, and relative humidity at peak Musala

Abstract

Some connections between aerosols, atmospheric transport, and relative humidity are investigated based on measurements at Basic Environmental Observatory (BEO) station, peak Musala (2,925 masl) for the period January 2009–January 2010. Data are chosen at 0:00 and 12:00 GMT every day. Main methods employed in this research are statistical—nonparametric tests of Mann–Whitney and Spearman. The main conclusion is that greater aerosol load at peak Musala is connected with transport of air masses from north to east horizon quarters. Bigger particles with longer lifetimes come from there. Air coming from the south horizon quarter is aerosol clearer. Relative humidity shows opposite distribution—higher values for transport from south horizon quarter. Correlation between this parameter and aerosols is negative with significant but small value. Distribution of blue, green, and red scattering and backscattering coefficients is similar to distribution of total aerosol concentration. Correlations between scattering and backscattering coefficients and total aerosol concentration are significant and positive. Courses of total aerosol concentration; diameter of particles with maximum concentration; and blue, green, and red scattering and backscattering coefficients have summer maximum and winter minimum. Diurnal course of total aerosol concentration in the two main seasons, winter (January) and summer (July), has day maximum and night minimum. Aerosols at peak Musala are predominantly of transparent or translucent type. The calculation of Angstrom exponent α is more precise by using scattering coefficients. The nephelometers data could successfully characterize the haziness of the atmosphere above peak Musala.