Airborne measurements of the number concentration and size distribution of aerosols from 13 to 700 nm diameter have been made at four vertical levels across a coastline at Bhubaneswar (20° 25′N, 85° 83′E) during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) programme conducted in March–April 2006. The measurements made during the constant-level flights at 0.5, 1, 2 and 3 km altitude levels extend ∼100 km over land and ∼150km over ocean. Aerosol number concentrations vary from 2200 to 4500 cm-3 at 0.5 km level but are almost constant at ∼6000 cm-3 and ∼800 cm-3 at 2 and 3 km levels, respectively. At 1km level, aerosol number concentration shows a peak of 18,070 cm-3 around the coastline. Most of the aerosol size distribution curves at 0.5 km and 1 km levels are monomodal with a maxima at 110nm diameter which shifts to 70 nm diameter at 2 and 3 km levels. However, at the peak at 1 km level, number concentration has a bimodal distribution with an additional maximum appearing in nucleation mode. It is proposed that this maxima in nucleation mode at 1 km level may be due to the formation and transport of new particles from coastal regions.
Volume 129, 2020
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