Mixing of atmospheric gas concentrations

Atmospheric gas concentrations were measured at I s intervals in the upper troposphere during a flight through and near the anvil of a storm. The obse rved very high correlations between the concentrations of CO and CH4 are in terpreted as arising from the mixing of two distinct air masses with differ ing concentrations of each species, and is due to the nearly identical diff usivities of CO and CH4 in air. We find that the correlations depend on the period over which each concentration measurement was made. Correlations in measurements made over short periods decay with time, while correlations o ver larger scales remain high. We interpret this using a simple mixing mode l.