Elucidating New Particle Formation in Complex Terrain During the Winter
2022 Cold Fog Amongst Complex Terrain (CFACT) Campaign
Abstract
New particle formation (NPF) is a complex atmospheric phenomenon defined
by the gas-to-particle conversion that leads to the sudden burst and
growth in aerosol particles. Extensive prior ambient, laboratory and
chamber studies have demonstrated chemical mechanisms within the
atmosphere that allow for aerosol nucleation and subsequent growth. A
deeper understanding of the physical mechanisms within the atmosphere
enhancing NPF are beginning to emerge with recent studies. For example,
processes within the atmospheric boundary layer (ABL), such as turbulent
mixing, can lead to the decoupling and recoupling of different
atmospheric reservoirs to create favorable conditions that help initiate
NPF. Using observations from the 2022 CFACT (Cold Fog Amongst Complex
Terrain) field study conducted in the Heber Valley of northern Utah,
this study demonstrates an interconnection between turbulence and the
occurrence of NPF. The CFACT field study incorporated spatially
distributed boundary layer instrumentation on a scale not typically seen
in previous literature. Three case studies are presented that depict
unique boundary layer conditions that modulate the development of NPF,
characterized by sustained turbulence and weak intermittent turbulence.
This analysis presents in situ measurements and derived variables to
quantify the relationship between specific boundary layer processes and
NPF.