Atmospheric Radiation Measurement Climate Research Facility US Department of Energy



Tropospheric Ozone Variability during LASIC

24 July 2017 - 5 October 2017

Lead Scientist: Gregory Jenkins

Observatory: AMF

A unique opportunity exists to examine high frequency vertical profiles of tropospheric ozone and its relationship to biomass burning aerosols and the African Easterly Jet- South during August/September 2017 during the wave-one ozone maximum over the South Tropical Atlantic (STA) when high quality ground based aerosol measurements are available during the LASIC field campaign at Ascension Island. The LASIC field campaign using the AMF1 during its intensives have launched 4-8 radiosondes per day Ascension Island. In addition the Micropulse lidar (MPL) provides vertical profiles of biomass burning aerosol layers that are transported from Africa. Since April 2016, the NASA SHADOZ site has begun taking vertical profiles of ozone at Ascension Island. However, these profiles of ozone occur only once per week. Daily AERONET data and reanalysis of the 700 hPa winds show that the limited ozonesondes are not capturing the variability of either aerosols or 700 hPa winds associated with the AEJ-S. Consequently, because aerosols and ozone plumes have their source of Southern Africa and are transported westward by the AEJ-S the ozone sampling that is currently taking place is most likely not capturing ozone variability.

There are three objectives that we wish to achieve in the proposed work:

1.Collect high frequency vertical profiles (3 additional) with a focus on tropospheric ozone to compliment the weekly SHADOZ ozone profiles at Ascension Island. Some of the ozonesonde launches should occur under limited cloudy conditions. 2.Document episodes of biomass burning aerosol events (using lidar) and its relationship to vertical profiles of ozone mixing ratios through high frequency ozonesonde launches. 3.Determine how vertical profiles of ozone mixing ratios vary in the active/inactive phases of the AEJ-S which is identified with high frequency LASIC radiosonde measurements and how it leads to variations in the lower to middle tropospheric ozone mixing ratios and aerosol loading at Ascension Island.