Biogenic Aerosols - Effects on Clouds and Climate (C-band radar)

The Biogenic Aerosols - Effects on Clouds and Climate (BAECC) experiment provided a bridge from a 19-year long in-situ observation record to the impact of biogenic aerosol on clouds, precipitation and climate. This was achieved by simultaneous observations of precursor vapor emission, aerosol, cloud and precipitation microstructure. This dataset was used to: (1) link precursor emissions and aerosol, (2) link aerosol at the surface to aerosol in the mixed layer, (3) investigate the aerosol indirect effect on clouds and precipitation. To achieve those goals the Atmospheric Radiation Measurement Mobile Facility (AMF) was deployed in Hyytiälä, Finland, for a period of 7.5 months starting in January 2014, to capture the seasonal variability of biogenic aerosol at this boreal environment site. The experiment took place at the University of Helsinki SMEAR II research station, which has been monitoring biosphere-atmosphere interactions continuously since 1996.

The ARM AMF observations were supplemented by tower and surface-based measurements of aerosol and precursor gases. During intensive observation periods (IOPs) aircraft observations of aerosol microphysics were performed. The experiment also benefited from existing measurements of precipitation provided by the Finnish Meteorological Institute observational network. The 7.5 month dataset was placed in perspective with the long time series available from Hyytiälä, and utilized in modeling efforts ranging from process models to global climate models, capitalizing on the ability to perform radiative transfer calculations with full closure.