Primary marine aerosol-cloud interactions off the coast of California

R. L. Modini, A. A. Frossard, L. Ahlm, L. M. Russell, C. E. Corrigan, G. C. Roberts, L. N. Hawkins, J. C. Schroder, A. K. Bertram, R. Zhao, A. K.Y. Lee, J. P.D. Abbatt, J. Lin, A. Nenes, Z. Wang, A. Wonaschütz, A. Sorooshian, K. J. Noone, H. Jonsson, J. H. SeinfeldD. Toom-Sauntry, A. M. Macdonald, W. R. Leaitch

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


Primary marine aerosol (PMA)-cloud interactions off the coast of California were investigated using observations of marine aerosol, cloud condensation nuclei (CCN), and stratocumulus clouds during the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE) and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets (SOLEDAD) studies. Based on recently reportedmeasurements of PMA size distributions, a constrained lognormal-mode-fitting procedure was devised to isolate PMA number size distributions fromtotal aerosol size distributions and applied to E-PEACEmeasurements. During the 12 day E-PEACE cruise on the R/V Point Sur, PMA typically contributed less than 15% of total particle concentrations. PMA number concentrations averaged 12 cm-3 during a relatively calmer period (average wind speed 12m/s1) lasting 8 days, and 71 cm-3 during a period of higher wind speeds (average 16m/s1) lasting 5 days. On average, PMA contributed less than 10% of total CCN at supersaturations up to 0.9% during the calmer period; however, during the higher wind speed period, PMA comprised 5-63% of CCN (average 16-28%) at supersaturations less than 0.3%. Sea salt was measured directly in the dried residuals of cloud droplets during the SOLEDAD study. The mass fractions of sea salt in the residuals averaged 12 to 24% during three cloud events. Comparing the marine stratocumulus clouds sampled in the two campaigns, measured peak supersaturations were 0.2 ± 0.04% during E-PEACE and 0.05-0.1% during SOLEDAD. The availablemeasurements show that cloud droplet number concentrations increased with > 100 nmparticles in E-PEACE but decreased in the three SOLEDAD cloud events.

Original languageEnglish (US)
Pages (from-to)4282-4303
Number of pages22
JournalJournal of geophysical research
Issue number9
StatePublished - 2015

ASJC Scopus subject areas

  • Geophysics
  • Oceanography
  • Forestry
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology


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