Aircraft measurements of CO2, O3, water vapor, aerosol fluxes and, turbulence over Lake Michigan

Abstract

Using an instrumented aircraft we made a constant altitude flight over lake Michigan near the Chicago shoreline and about 50 km downwind of it. The flight was made on June 18, 1992 between about 1:30 and 3:30 pm. The wind was southwesterly averaged about 12 m s^-1. Employing the eddy correlation method we calculated the fluxes of CO₂, O₃, water vapor and aerosols in the diameter range of 0.1 to 3.0 µm. The fluxes near the shoreline were found to be significantly higher than those in the middle of the lake. The fluxes near the shoreline for O₃ and aerosols were directed toward the surface and corresponding to transfer (deposition) velocities of 0.15 cm s^-1 and 0.86 cm s^-1, respectively. For CO₂, and water vapor, the fluxes were directed upward and corresponding to transfer velocities of 0.04 cm s^-1 and 0.54 cm s^-1, respectively. At mid-lake the fluxes of O₃ and water vapor were directed upward and corresponding to transfer velocity of 0.045 cm s^-1 and 0.003 cm s^-1. For CO₂ and aerosols the fluxes were directed downward and corresponding to transfer (deposition) velocities of 0.006 cm s^-1 and 0.226 cm s^-1.