New particle formation: Nucleation rates and spatial scales in the clean marine coastal environment

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Abstract
Nucleation of new, ultra‐fine, aerosol particles has been observed in the clean marine coastal atmosphere under a variety of conditions. These nucleation events were observed to occur frequently over spatial scales of 10's–100' of metres and temporal scales of seconds to minutes. Two conditions appeared to be necessary for nucleation event to occur: low tide and solar irradiation. The requirement of low tide conditions suggests that the exposed shore area provides the source of new particle precursors. It is speculated that VOC and/or alkyl halide derivatives contribute to nucleation under these conditions. Nucleation rates were calculated to be ≈ 10³ − 104 cm−3 s−1, suggesting that the coastal zone is an important source of atmospheric nuclei.