Measurements of the entrainment of hydrogen peroxide into cloud systems

Abstract

Detailed measurements from an aircraft of the vertical structure of hydrogen peroxide with detailed ground-based measurements of the chemistry of an aistream entering a hill cap cloud are presented together with measurements of the microphysics and chemistry of the cloud. Two case studies have been selected in which the cloud is being affected by the entrainment of air from outside its boundaries. The major findings are: (1) when the boundary layer is polluted the concentration of gas-phase hydrogen peroxide was observed to increase markedly with altitude in the lower troposphere; (2) the maximum concentrations of hydrogen peroxide were found close to the surfaces of clouds and were up to 10 times greater than concentrations in the boundary layer on the same day and (3) the entrainment of this hydrogen peroxide into the cap cloud had a profound effect on the chemistry of the cloud.