Objectives (5 yr plan)

• 3.3.1 To take high precision measurements of CO 2 concentrations and 14C at one to two tall towers at the in- and outflow of the domain.
• 3.3.2 To perform regular flights with small aircraft to sample the boundary evolution of CO 2 concentrations and 13C.
• 3.3.3 To perform at fixed locations continuous measurements of windspeed and temperature in the boundary layer with a profiling system.
• 3.3.4 To perform twice daily radio soundings at a regular radio sounding site in Bordeaux , augmented with an intensive campaign in the summer of 2005 where bi-hourly releases will track the evolution of the boundary layer.

Outline of work plan

Task 3.3.1 Tall tower-based scalar concentration measurements. The installation of the two towers is detailed in the 18 month workplan. At the inflow and outflow positions of the domain (near Toulouse and Bordeaux ) one to two towers equipped with high precision gas chromatographs will measure the concentrations of CO 2, and 14C (depending on national resources). CMDL NDIR-CO 2 sensors are built for this purpose. Implementation will start in 2005.

Task 3.3.2 Airborne flask sampling. A small commercial plane will sample the boundary layer structure for CO 2, 13C and CO for 3 to 5 days. Flask samples will be analysed at MPI-BGC. During the intensive campaign, flights are planned on 1 day every week to take 3 profiles at 5 levels in the boundary layer.

Task 3.3.3 Radio soundings. We will extend the routine WMO observations at Bordeaux during the test campaign and later during the full campaigns. We will also install UHF profile systems and RASS_Sodar systems at a location where they contribute most to our understanding of the heterogeneity of the area.