Vertical Profiles and Seasonal Variations of Key Parameters Controlling Particle Formation and Growth at Storm Peak Laboratory

Fangqun Yu,Gan Luo,A Gannet Hallar

doi:10.4209/aaqr.2015.05.0368

Abstract

ABSTRACTHere 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.

Highlights

New particle formation (NPF), frequently observed at various locations around the globe (Kulmala et al, 2004; Yu et al, 2008), largely determines the particle number concentrations in most part of troposphere and is an important source of cloud condensation nuclei (CCN) (Spracklen et al, 2008; Pierce and Adams, 2009; Yu and Luo, 2009)
The vertical profiles of key parameters relevant to new particle formation (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
With these limitations kept in mind, it can be seen from Fig. 1 and Table 1 that the model overall captures absolute values of condensation nuclei larger than 10 nm (CN10) and their variations, especially in the spring months (March–May) where regional scale NPF occurred frequently (Fig. 1(b))

Summary

Introduction

New particle formation (NPF), frequently observed at various locations around the globe (Kulmala et al, 2004; Yu et al, 2008), largely determines the particle number concentrations in most part of troposphere and is an important source of cloud condensation nuclei (CCN) (Spracklen et al, 2008; Pierce and Adams, 2009; Yu and Luo, 2009). Yu and Hallar (2014) investigated in detail the NPF during the two contrasting months (March and July, 2012) at SPL, through comparisons of aerosol measurements with model simulations based on a global chemical transport model (GEOS-Chem) coupled with a size-resolved advanced particle microphysics (APM) model.

Results

Conclusion