Seasonal variability of aerosol properties at Issyk-Kul Station, Kyrgyzstan

This investigation quantifies the spatiotemporal variability of atmospheric aerosol properties at the Issyk-Kul AERONET site (42.48°N, 77.55°E, 1650 m ASL) through analysis of sun photometer measurements (2019-2024). Utilizing CIMEL CE318-derived Level 1.5 and 2.0 data products, we characterize aerosol optical depth (AOD500), Ångström exponent (AE440-870), and precipitable water (PW) dynamics in this topographically complex basin surrounded by the Tien Shan mountains. Key findings demonstrate: (1) bimodal AOD500 seasonality (spring: 0.18±0.05, summer: 0.20±0.06) linked to synoptic-scale dust transport and local anthropogenic sources; (2) distinct AE440-870 regimes (winter: 1.2±0.3, summer: 1.5±0.4) indicating variable fine/coarse particle mixing; (3) PW maxima (4.5±0.8 cm) during summer convective periods. Statistical analysis reveals significant (p<0.01) interannual trends in aerosol loading correlated with regional climate indices. The results highlight three critical mechanisms governing aerosol variability: orographic modulation of air masses, seasonal source regime shifts, and boundary layer - free troposphere exchange processes. These observations provide essential constraints for improving radiative forcing parameterizations in regional climate models (RegCM, WRF-Chem) and inform air quality management strategies across Central Asia’s mountain basins.