Average diurnal cycles of both gas- and aerosol-phase nitrate, ammonia, and sulphate for (left) Portland and (right) Alabama sites.
Atmospheric aerosols exert a large but uncertain negative (cooling) radiative forcing on regional climate.
Their chemical composition affects this climate forcing via aerosol hydroscopicity and consequential cloud interactions, as well as providing clues to the chemical origins of the aerosol.
MARGA
A Metrohm Monitor for AeRosol and GAses in ambient air (MARGA) instrument was used in summer 2013 as part of the Southeastern Oxidant and Aerosol Study (SOAS), a large field campaign that took place in Centerville, Alabama, USA.
MARGA was used to measure the inorganic composition of aerosols and the key gases (HNO3, NH3, SO2) in equilibrium with each aerosol, enabling elucidation of aerosol composition and inferences about origin.
The data from this summer field study are compared to data collected in the Pacific Northwest in autumn 2013, a comparison which helps to isolate the roles of varying regional SO2 sources, humidity, and temperature on aerosol composition and loading.
