Seasonal significance of new particle formation impacts on cloudcondensation nuclei at a mountaintop location

New particle formation (NPF) events are defined as asudden burst of aerosols followed by growth and can impact climate bygrowing to larger sizes and under proper conditions, potentially formingcloud condensation nuclei (CCN). Field measurements relating NPF and CCN arecrucial in expanding regional understanding of how aerosols impactclimate. To quantify the possible impact of NPF on CCN formation, it isimportant to not only maintain consistency when classifying NPF events butalso consider the proper timeframe for particle growth to CCN-relevantsizes. Here, we analyze 15 years of direct measurements of both aerosol sizedistributions and CCN concentrations and combine them with novel methods toquantify the impact of NPF on CCN formation at Storm Peak Laboratory (SPL),a remote, mountaintop observatory in Colorado. Using the new automaticmethod to classify NPF, we find that NPF occurs on 50 % of all daysconsidered in the study from 2006 to 2021, demonstrating consistency withprevious work at SPL. NPF significantly enhances CCN during the winter by afactor of 1.36 and during the spring by a factor of 1.54, which, when combined withprevious work at SPL, suggests the enhancement of CCN by NPF occurs on aregional scale. We confirm that events with persistent growth are common inthe spring and winter, while burst events are more common in the summer andfall. A visual validation of the automatic method was performed in thestudy. For the first time, results clearly demonstrate the significantimpact of NPF on CCN in montane North American regions and the potential forwidespread impact of NPF on CCN.