1. Chemistry measurements In-situ measurements of NO 2 and tracers (like CH 4 or N 2 O to identify the origin of the air masses) Infra red Quantum Cascade Lasers (SPIRIT, lighter version of SPIRALE) Technique of measurement

2. Remote sensing measurements using Moon and Sun as light sources (line of sights at least ten times smaller than for satellite instruments) (lighter version of SALOMON) SALOMON NO 2 measurements

3. : In-situ measurements: Accurate estimation of the concentration, but lower probability to cross a local enhancement Remote sensing-measurements: Higher probability to detect the enhancement but underestimation of the absolute values of the concentrations (“dilution” effect) => Need to combine the two techniques (by using the two instruments in the same or in different gondolas)

4. Strategy of measurements Simultaneous measurements from satellites and balloon of the regions that produce the TLE and TGF Choice of a launching site: “Safe” tropical region with possibility of CNES installation Best probability of detection of TLE and TGF

5. TLE: a)a) b)b) c) d)d) Lightning

6. TGF:

7. Best solution : Launch from Kourou (at least for the first campaigns) Launch during weak stratospheric winds in order to stay close to the launching site for about 10 days

8. Recovery: - can we accept to lose the gondolas ? - recovery in the sea ? But 10 days of measurements is better than 10 flights of several hours … Several gondolas: Risk of losing the payloads Different scientific objectives (TLE, TGF, chemistry) 1 campaign per 18 months during the lifetime of Taranis and/or ASIM ?

9. Main issues to be solved Telemetry limitation Needs of technical flights to test the long duration balloons and the new instruments Project under construction Project submitted to CNES in 2009 Discussions with ESA for the project in the frame of ASIM