Motivations for the 2017 CPOC pilot study and ongoing studies at WFM
Aqueous chemical processing within cloud and fog water has been identified as a key process in the formation of secondary organic aerosol (SOA) mass.
Organic compounds are found abundantly within aerosol particles throughout the troposphere, but there remain major uncertainties regarding how organics
chemically transform and end up in the aerosol phase. While clouds clean the atmosphere by removing aerosol particles via rain and snow, clouds can also
impart mass to pre-existing aerosol particles by acting as aqueous phase micro-reactors. Aerosols, in turn, control cloud microphysical properties, which
can affect whether, when and where rain falls. Thus, aerosols and clouds are inextricably linked, and one cannot be understood without the other.
Decades of research suggests that the impact of human emissions on clouds exerts a net cooling effect that may be nearly as large as the warming effect
from CO2 (although over a much shorter timescale). However, the aerosol-cloud relationship continues to be a highly uncertain aspect of Earth’s climate.
Whiteface Mountain (WFM) in northern New York State is one of the highest peaks in the Adirondacks and is an important sampling site for cloud chemistry because:
- the mountain top is within cloud 25-60% of the time during summer months,
- automated cloud water sampling often produces ample cloud liquid water (~1 liter) for each cloud event,
- decades of chemically-speciated measurements of cloud and rain water have been collected at the site, and
- due to its strategic location, the summit frequently intercepts pollution plumes that have undergone varying degrees of ‘aging’ during transport from various sources.
The large volumes of cloud water that are routinely collected at WFM allow for the ability to characterize a wide array of chemical compounds.
Long-term measurements from WFM have provided a unique and broad view of regional air quality and cloud-aerosol interactions, particularly relevant for
acid deposition to the Adirondack ecosystem. The CPOC pilot study and future planned intensive measurement campaigns at WFM will help researchers better understand the impact
clouds have on the chemical processing of organics within our ever-changing atmosphere, at the intersection of air quality and climate research.
