ABSTRACT
Surface measurements of the atmospheric electric field, conductivity, and the concentration and size distribution of submicron aerosols were made at Maitri, Antarctica, during the summer Indian Antarctic Expedition of 1996–1997. The main results obtained from these observations are summarized below:
The classical concept of the global electric circuit is not validated from the diurnal variation curves of the atmospheric electric field observed during this period. The value of electrical conductivity at the ground surface does not show much diurnal variation.
Aerosol size distributions at Maitri are generally trimodal and remain almost similar for several hours or even days in the absence of any meteorological disturbance. Total aerosol concentration increases by approximately an order of magnitude whenever a low-pressure system passes over the station.
Observations of aerosols and conductivity made during the onward and return journeys of the cruise strongly support the transport of aerosol and trace gases with the seasonal northeasterly winds from the Indian subcontinent to the Indian Ocean. From the differences observed in latitudinal variation in aerosols and conductivity along the cruise route, one can conclude that the downward transport of the nucleation mode particles from the free troposphere to the marine boundary layer significantly contributes to the nucleation mode particle high concentrations observed up to ITCZ.
Changes in the values of conductivity during two episodes of warm and cold fog are studied. Observations are interpreted in terms of ion-attachment and new particle generation processes.
