Cite this article: Yu, F., Luo, G. and Hallar, A.G. (2016). Vertical Profiles and Seasonal Variations of Key Parameters Controlling Particle Formation and Growth at Storm Peak Laboratory.
Aerosol Air Qual. Res.
16: 900-908. https://doi.org/10.4209/aaqr.2015.05.0368
Key parameters controlling particle formation at a mountain-top site are studied.
Reasons behind high frequency of nucleation in the spring and fall are discussed.
The model overall captures observed values of CN10 and their variations.
High CN10 concentrations are generally confined to the lower troposphere.
Here we compare model simulated number concentrations of condensation nuclei larger than 10 nm (CN10) in 2009 with those measured at the Storm Peak Laboratory (SPL), a high elevation mountain-top observatory in northwestern Colorado, US. We also investigate vertical profiles and seasonal variations of key parameters controlling particle formation and growth over this remote mountain-top site. The model overall captures absolute values of CN10 and their variations, especially in the spring months where regional scale new particle formation (NPF) occurred frequently. The model is able to predict the right magnitude of background CN10 values in July and August but it fails to reproduce the short-term spikes in CN10 and thus under-predicts the mean CN10 in these two months. The vertical profiles of key parameters relevant to NPF, including temperature and concentrations of SO2, secondary organic gases (SOG), OH, H2SO4 and low volatility SOG, show clear seasonal variations that lead to relatively high frequency of NPF in the spring and fall. Vertically, high concentrations of precursors and aerosol number concentrations are generally confined to the boundary layer and lower troposphere.
Keywords: New particle formation; Condensation nuclei; Mountain-top observatory; Global aerosol model; Ion-mediated nucleation