Certain meteorological features of submicron aerosols at schirmacher oasis, East Antarctica

Abstract

Using a Gardner Small Particle Detector, the concentrations of aerosol in the submicron size range 10 −7 to 10 −5 cm, also known as Aitken nuclei have been monitored at the Maitree Hills station in Antarctica during the summer from 14 January to 11 February 1987. In addition, the vertical distribution of concentrations of these nuclei from surface to 2 km level was measured both over the Maitree Hills region and in the vicinity of the Dakshin Gangotri station on the ice shelf. These observations reveal: 1. (i) maximum concentrations (46%) of Aitken nuclei are in the number density range up to 500 cm −3; 2. (ii) no systematic diurnal variation in nuclei concentrations was observed; 3. (iii) a close association between Aitken nuclei concentration and the intensity of vertical mixing was noticed. Low concentrations were found to be linked with convective clouds whereas the occurrence of stratus clouds was typical of high concentrations at the surface; 4. (iv) the vertical distributions showed higher nuclei concentrations at all levels over Maitree Hills region than over the ice shelf under clear sky conditions. For medium and high clouds, the Aitken nuclei counts at the surface were significantly higher over the ice shelf than over the Maitree Hills region; 5. (v) about 12 to 16 h in advance of an approaching frontal weather system, the nuclei count increased sharply sometimes to over 100,000 cm −3; 6. (vi) in situ formation of nuclei by gas to particle conversion together with wind erosion of exposed rocks and wave action on the nearby ocean surface are possible explanations for the high nuclei counts at the Maitree Hills station.