Physical properties of aerosols at Maitri,Antarctica |
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Authors: | C G Deshpande A K Kamra |
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Institution: | (1) Indian Institute of Tropical Meteorology, Pune, India |
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Abstract: | Measurements of the submicron aerosol size distribution made at the Indian Antarctic station, Maitri (70‡45′S, 11‡44′E) from
January 10th to February 24th, 1997, are reported. Total aerosol concentrations normally range from 800 to 1200 particles
cm−3 which are typical values for the coastal stations at Antarctica in summer. Aerosol size distributions are generally trimodal
and open-ended with a peak between 75 and 133 nm and two minima at 42 and 420 nm. Size distributions remain almost similar
for several hours or even days in absence of any meteorological disturbance. Total aerosol concentration increases by approximately
an order of magnitude whenever a low pressure system passes over the station. Based on the evolution of aerosol size-distributions
during such aerosol enhancement periods, three types of cases have been identified. The nucleation mode in all three cases
has been suggested to result from the photochemical conversion of the DMS emissions transported either by the marine air or
by the air from the ice-melt regions around Maitri. Subsidence of midtropospheric air during the weakening of radiative inversion
is suggested as a possible source of the nucleation mode particles in the third case. Growth of the nucleation mode particles
by condensation, coagulation and/or by cloud processes has been suggested to be responsible for other modes in size distributions. |
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Keywords: | Antarctic aerosols coastal aerosols aerosol size distribution aerosols transport with polar lows Maitri aerosols |
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