1. LPCE:CETP: CESR: LONG DURATION FLIGHTS OF BALLOONS FOR THE STUDY OF STRATOSPHERIC CHEMISTRY IN THE FRAME OF THE TARANIS PROJECT LPCE:Gwenaël BERTHET CETP: Elena SERAN Valéry CATOIREMichel GODEFROY Michel CHARTIER Francis VIVAT Nathalie HURET Dominique LAGOUTTE CESR: Pierre-Louis BLELLY François LEFEUVRE Jean-André SAUVAUD Aurélie MARCHAUDON François FORME Jean-Louis PINCON Claude ROBERT Michel TAGGER

2. This is a starting project, linked with TARANIS Measurements from balloons on stratospheric chemistry, but also on TGF, on electric fields, and on TLE

3. Stratospheric chemistry context: Production of NOx (NO+NO 2 ) in the upper stratosphere by high energy phenomena For example after strong solar eruption (high energy protons) Detection using satellite instruments over polar cap GOMOS onboard Envisat Nighttime measurements

4. Smaller enhancements expected during TLE/TGF events Satellite data are difficult to use for detection of such « local » NOx enhancements - Line of sight of several hundreds of km in the stratosphere (=> dilution of the absolute values of the enhancements) - Need of nighttime measurements (long persistence of the enhancements due to the absence of photochemistry)

5. Best solution : Use of instruments onboard stratospheric balloons up to altitude of 40 km Remote sensing and in-situ measurements Gondolas up to few hundreds of kg Need of “long duration flights” (at least several days) to stay close to thunderstorm areas

6. At present, long duration flights (several days to several weeks) with: MIR (infrared balloons) BP (pressurized balloons)

7. Problems : - scientific payloads of few tens of kg maximum - need of using chemistry instruments of around 100 kg and TGF (and TLE) instruments of several tens of kg - flights not possible above storms and large cloud expanses Solution : use of conventional stratospheric balloons (BSO) - flights of at least 10 days - payloads up to 200 kg - flight altitude up to 40 km

8. We propose gondolas with different instruments for: - Measurements of stratospheric species by in-situ and remote sensing techniques - Detection of terrestrial gamma rays flashes - Electric fields measurements (to be defined …) - Detection of TLE by fast cameras

9. Terrestrial Gamma-ray Flashes Balloons can allow us to perform in situ measurements Between 20 and 40 km, good probability of detecting TGF Use of an already existing balloon-borne instrument (that needs to be improved …)

10. TLE: Fast cameras LONG DURATION FLIGHTS ATLEC Atmospheric Transient Luminous Event Camera Survey of lightning – TLE - 3D - spatial resolution of 2° (up to 0.5°) - temporal resolution/exposition: ~1 ms - dynamics: 0.01-100 MR - wave length: 380-850 nm

11. Stratospheric chemistry: SPIRIT – instrument under development In-situ measurements of NO 2 and tracers (CH 4, N 2 O to identify the origin of the air masses) Infra red tunable laser diode Typical NO 2 measurements above Brazil Mixing ratios Technique of measurement

12. SALOMON-JN Remote sensing measurements using Moon and Sun as light sources (line of sights at least ten times smaller than for satellite instruments) Improvement (under development) of the already existing SALOMON instrument SALOMON NO 2 measurements

13. : In-situ measurements: accurate estimation of the concentration, but lower probability to cross a local enhancements : Remote sensing-measurements: higher probability to detect the enhancements 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 gondolas or in different gondolas)

14. Strategy of measurements Choose of the launching site: “Safe” tropical regions with possibility of CNES installation North Brazil (Teresina) ? Kourou (French Guyana) ?

15. Needs of technical flights before the launch of TARANIS to test the long duration balloons and the new instruments … Launch during weak stratospheric winds in order to stay close to the launching site (better probability of safe recovery) At least two different gondolas (risk of loosing the payloads) ? 1 campaign per 18 month ?

16. Project under construction Submission of the project to the CNES balloon workshop (PAU September 2008) Final project submitted to CNES in 2009 New contributions welcome, including ground-bases measurements…