Methane and other Trace Gases in the Indian Summer Monsoonal Outflow as Measured by the Civil Aircraft Based Research Project CARIBIC

Monthly recurring flights between Europe and India with the CARIBIC aircraft (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container, www.caribic-atmospheric.com) intercept the easterly outflow over the Indian subcontinent in summer at the cruising altitude of 10-12 km. While the route of the aircraft remains unchanged during the year, profound changes in the trace gas concentrations, particularly methane, and aerosol number densities are observed when the monsoon plume is crossed. The highly detailed information is used to estimate emission ratios for this continental type of emission plume, and to understand the processes. On this basis source strengths can be estimated. Comparisons with results from satellite observations and modeling are given.