Variability of Atmospheric Aerosol Optical Depth over the Northern Tian Shan

N. I. Sizov, R. M. Akimenko, V. N. Aref’ev, F. V. Kashin, M. D. Orozaliev, V. P. Sinyakov, and L. I. Sorokina

Presented are the data of measurements of aerosol optical depth (AOD) of the atmosphere at the wavelength of 500 nm for the period from 1984 to 2009 at Issyk Kul monitoring station located in the central part of Eurasia. The decrease in AOD by about 4.3% took place during the measurement period. Revealed are the seasonal variations, linear trends, and periods of AOD increase associated with volcanic eruptions. The spectral analysis of measurement data using the Fourier and wavelet transforms enabled determining the basic characteristics of the constituents of AOD variations. The linear trend changes from positive to negative from 1995 to 2009 that may indicate increase in the amount of aerosol in these years. Proposed is a simple statistical model for describing the temporal variations of AOD.