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

Autor: G. R. Aher, Panuganti C. S. Devara, Sandeep R. Varpe, G. V. Pawar, Amol R. Kolhe, P. Pradeep Kumar
Rok vydání: 2016
Předmět:
Zdroj: Aerosol and Air Quality Research. 16:3266-3280
ISSN: 2071-1409
1680-8584
DOI: 10.4209/aaqr.2016.06.0268
Popis: The present study evaluates the temporal variation of aerosol optical depth (AOD500 nm) and the Angstrom parameters [viz., Angstrom exponent (AE, α), Angstrom turbidity coefficient (β) and second order Angstrom 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 pre-monsoon seasons together are found to be 0.534 ± 0.13, 1.054 ± 0.27, 0.254 ± 0.08 and 0.167 ± 1.33 for AOD500 nm, AE, β and α′ respectively. Average month-to-month variability of AOD500 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 AOD500 nm–AE440-870 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.
Databáze: OpenAIRE
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