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P.v. Joshi - One of the best experts on this subject based on the ideXlab platform.

  • Distribution of atmospheric ions and Aitken Nuclei over southern oceans and polar regions
    Environment International, 1992
    Co-Authors: P.v. Joshi
    Abstract:

    Abstract In the Eighth Indian Antarctic Expedition, measurements on atmospheric ions and Aitken Nuclei were carried out over southern oceans and at an oasis in the Antarctica. The levels are found to be decreasing towards high latitudes. They are found to be log-normally distributed. Based on these data, some inferences have been made. Background levels of both the species have been described. Their dependence on background levels has been discussed. It seems that at background levels, the inverse relationship between atmospheric ions and Aitken Nuclei may not hold.

Peter V. Hobbs - One of the best experts on this subject based on the ideXlab platform.

D. Nganga - One of the best experts on this subject based on the ideXlab platform.

  • Ozone and Aitken Nuclei over equatorial Africa: Airborne observations during DECAFE 88
    Journal of Geophysical Research, 1992
    Co-Authors: Meinrat O. Andreae, Jacques Fontan, A. Chapuis, B. Cros, G. Helas, Christopher O. Justice, Yoram J. Kaufman, A. Minga, D. Nganga
    Abstract:

    We determined the distribution of ozone (O3) and Aitken condensation Nuclei (CN) over the rain forest in equatorial Africa during February 12–25, 1988. A pronounced O3 maximum with levels up to 70 ppbv was present in a layer between 1 and 3 km altitude throughout the period. It coincided with a CO maximum and with high levels of CO2 and gaseous organic acids. In general, the vertical distribution of CN was similar to that of O3, with number densities ranging up to approximately 3000 cm−3. Dense haze was visible within this layer. O3 and CN decreased sharply above the haze layer to values typical of the remote troposphere. Survey flights showed little change in levels of O3 and CN or in their vertical distribution over distances of hundreds of kilometers. Meteorological observations suggest that this ozone and particulate enriched layer is formed from air masses which originate in northern Africa and subsequently advect over dry tropical regions where biomass burning emits large amounts of aerosols, CO, NO, and hydrocarbons. These air masses then become trapped in the equatorial region between the near-surface monsoon flow from the southeast and the permanent easterly flow above 3–4 km. Differences in the vertical distribution of O3 and CN result from the removal of O3 by surface uptake and reactions with NO and hydrocarbons, leading to surface O3 concentrations near zero and a steep O3 gradient through the subcloud layer at night. During the day this gradient is reduced by convective mixing. CN concentrations showed no pronounced gradients in the subcloud layer, consistent with the absence of a strong sink for CN at the ground. CN gradients near the surface suggest emission of particles from the forest vegetation or from biomass burning.

Dean A. Hegg - One of the best experts on this subject based on the ideXlab platform.

P.s. Prakasa Rao - One of the best experts on this subject based on the ideXlab platform.

  • Some observations on the characteristics of aerosols at traffic junctions in Pune city
    2004
    Co-Authors: P.d. Safai, G. A. Momin, P.s. Prakasa Rao, Kaushar Ali, D. M. Chate, P. S. Praveen
    Abstract:

    Vehicular emissions are one of the potential sources of air pollution, especially in the urban regions. Pune, one of the rapidly growing cities of India, faces a severe threat from this problem. Observations of Total Suspended Particulates (TSP) and Aitken Nuclei (AN) were conducted at four traffic junctions in the city during summer (May 2000) and winter (Jan-Feb 2001). Concentrations of TSP were very high at all the traffic junctions and also the number density of AN was very high. Concentrations of all the measured constituents were more, except NH4 and Cu, at traffic junctions than those reported at Pashan, a semi-rural location, comparatively away from vehicular effects.

  • Characteristics of aerosols at traffic junctions in Pune city
    2004
    Co-Authors: P.d. Safai, G. A. Momin, P.s. Prakasa Rao, Kaushar Ali, Naik, D. M. Chate, P. S. Praveen
    Abstract:

    Vehicular emissions are one of the potential sources of air pollution in the urban regions. Pune, one of the rapidly growing cities of India, faces the severe threat from this problem. Observations of total suspended particulates and Aitken Nuclei were conducted at 4 traffic junctions in Pune city during summer (May 2000) and winter (Jan-Feb. 2001). Concentrations of TSP crossed the CPCB limit, recommended for commercial zone, at all the traffic junctions and also the number density of Aitken Nuclei was very high. However, aerosols were alkaline in nature, in spite of high concentrations of SO4 and NO3, mainly due to the neutralizing effect of Ca, NH4, Na, Mg and K.

  • Studies of trace gases and Aitken Nuclei at inland and coastal stations - A part of INDOEX programme
    Current Science, 1999
    Co-Authors: P.s. Prakasa Rao, G. A. Momin, Pramod D. Safai, Kaushar Ali, Naik, A.g. Pillai
    Abstract:

    As a part of the Indian Ocean Experiment (INDOEX) programme, ground-based measurements of trace gases (SO2, NO2, NH3 and O3) and Aitken Nuclei (AN) were carried out at Pune during March-April 1998. Also, measurements of surface ozone and AN were made during 5-10 January 1998, the inter comparison campaign of various instruments at Thiruvananthapuram. The mean concentrations of SO2, NO2, NH3 and O3 at Pune were 3.75, 5.81, 3.21 and 57.8 I¼g/m3 respectively and that of O3 at Thiruvananthapuram was 44 I¼g/m3. The average concentration of AN was about five times higher at Pune (19,000/cm3) than that at Thiruvananthapuram (4,400/cm3), indicating more pollution at Pune than at Thiruvananthapuram. The diurnal variation of surface ozone showed high concentrations during the day and low concentrations during the night at both the locations. Diurnal variation of AN at Pune showed a daytime maximum and a night-time minimum. Whereas, at Thiruvananthapuram night-time values were higher than the daytime values which can be attributed to the influence of the land and sea breeze.

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