Multi-Year Analysis of Aerosol Properties Retrieved from the AngstromParameters for Different Spectral Ranges over Pune

Amol R. Kolhe ； Ganesh V. Pawar ； Sandeep R. Varpe ； Pallath Pradeep Kumar ； Panuganti C. S. Devara ； Gajanan R. Aher

《Aerosol and Air Quality Research》 16卷12期 (2016/12) Pp. 3266-3280

https://doi.org/10.4209/aaqr.2016.06.0268

摘要

The present study evaluates the temporal variation of aerosol optical depth (AOD_(500 nm)) and the Angström parameters [viz., Angström exponent (AE, α), Angström turbidity coefficient (β) and second order Angström exponent (α')] at a tropical observing site, Pune (18°32'N; 73°49'E, 559 m AMSL) during 2008–15. Six-year means for winter and premonsoon seasons together are found to be 0.534 ± 0.13, 1.054 ± 0.27, 0.254 ± 0.08 and 0.167 ± 1.33 for AOD_(500 nm), AE, β and α' respectively. Average month-to-month variability of AOD_(500 nm), AE, β and α' during 2008–15 depicts seasonal cycle with strong departures with respect to long-term means. Frequency distributions for AOD, AE and β are positively skewed (skewness = 0.77, 0.32 and 1.14 respectively) while it is negatively skewed for α' (skewness = -0.18). Analysis of AE difference, curvature parameter difference (α2-α1) and AOD_(500 nm)-AE_(440-870) nm contour density map reveals that the aerosol ensemble at Pune consists of four aerosol types viz., UI (urban/industrial), CM (clear maritime), DD (desert dust) and MT (mixed type). Their relative magnitudes, however, differ during winter and pre-monsoon seasons. Thus, the contour density map shows dominance of UI and relatively less occurrence of MT type aerosols during winter. In pre-monsoon, however, the aerosol scenario is driven by MT type aerosol although UI and DD type aerosols show their remarkable existence.

關鍵字

Aerosol optical depth ； Angstrom exponent ； Angstrom turbidity coefficient ； Aerosol loading ； Aerosol sources