The optical and physical properties of atmospheric aerosols over the Indian Antarctic stations during southern hemispheric summer of the International Polar Year 2007–2008

Abstract. The properties of background aerosols and their dependence on meteorological, geographical and human influence are examined using measured spectral aerosol optical depth (AOD), total mass concentration (M_T) and derived number size distribution (NSD) over two distinct coastal locations of Antarctica; Maitri (70° S, 12° E, 123 m m.s.l.) and Larsemann Hills (LH; 69° S, 77° E, 48 m m.s.l.) during southern hemispheric summer of 2007–2008 as a part of the 27th Indian Scientific Expedition to Antarctica (ISEA) during International Polar Year (IPY). Our investigations showed comparable values for the mean columnar AOD at 500 nm over Maitri (0.034±0.005) and LH (0.032±0.006) indicating good spatial homogeneity in the columnar aerosol properties over the coastal Antarctica. Estimation of Angstrom exponent α showed accumulation mode dominance at Maitri (α~1.2±0.3) and coarse mode dominance at LH (0.7±0.2). On the other hand, mass concentration (M_T) of ambient aerosols showed relatively high values (≈8.25±2.87 μg m⁻³) at Maitri in comparison to LH (6.03±1.33 μg m⁻³).