Airborne measurements of nucleation mode particles I: coastal nucleation and growth rates
A light aircraft was equipped with a bank of Condensation Particle\nCounters (CPCs) (50% cut from 3�5.4�9.6 nm) and a nano-Scanning Mobility\nParticle Sizer (nSMPS) and deployed along the west coast of Ireland,\nin the vicinity of Mace Head. The objective of the exercise was to\nprovide high resolution micro-physical measurements of the coastal\nnucleation mode in order to map the spatial extent of new particle\nproduction regions and to evaluate the evolution, and associated\ngrowth rates of the coastal nucleation-mode aerosol plume. Results\nindicate that coastal new particle production is occurring over most\nareas along the land-sea interface with peak concentrations at the\ncoastal plume-head in excess of 106 cm-3. Pseudo-Lagrangian studies\nof the coastal plume evolution illustrated significant growth of\nnew particles to sizes in excess of 8 nm approximately 10 km downwind\nof the source region. Close to the plume head (<1 km) growth rates\ncan be as high as 123�171 nm h-1, decreasing gradually to 53�72 nm\nh-1 at 3 km. Further along the plume, at distances up to 10 km, the\ngrowth rates are calculated to be 17�32 nm h-1. Growth rates of this\nmagnitude suggest that after a couple of hours, coastal nucleation\nmode particles can reach significant sizes where they can contribution\nto the regional aerosol loading.