222Rn observations for climate and air quality studies

Abstract

This paper identifies the current major applications for 222Rn in atmospheric research. Two of these applications, air mass transport and vertical mixing in the lower atmosphere, are illustrated by four separate case studies: (1) Using 222Rn to identify the geographical extent, strength and seasonal variability of land and oceanic emissions; (2) Using 222Rn in pollution studies to improve the performance of clustering algorithms used to define source regions; (3) Using near-surface hourly 222Rn gradient observations from towers as tall as 200 m to investigate diurnal dilution effects in the boundary layer with changing atmospheric stability; and (4) Using vertical 222Rn profile 'snapshots' measured from light aircraft up to 4 km above ground level to contrast boundary layer entrainment rates between clear-sky, convective and stratiform cloud cases. Lastly, a recent set of 222Rn and 222Rn progeny observations is used to discuss the 222Rn/progeny equilibrium factor and illustrate some common problems associated with using 222Rn progeny as a proxy for 222Rn.