1. Tropical Convection and UTLS Transport
Jean-Pierre Pommereau
CNRS Service d’Aéronomie,
Verrières le Buisson, France

2. Troposphere-Stratosphere Transport
0-14 km Fast (hours) convective transport up to Layer of Neutral Buoyancy (LNB), the base of Tropical Tropopause Layer (TTL)
14-20 km Current understanding: Slow (6 months) ascent by radiative heating
Question: contribution of fast (hours) cumulonimbus overshooting ?
0.4 km/month
Corti et al 2005

3. IMPACT OF OVERSHOOTING UPDRAFTS ?
C PT
STRATOSPHERE
TROPOSPHERE
O km
1O km
16-17 km
20 km
14 km
Top TTL
Bottom TTL ?
Temperature
TTL
How high ? Where ? How frequent ? How important at global scale?

4. Where and When ? SH Summer NH Summer
Hibiscus / Troccinox Feb 2004 and 2005
SCOUT Darwin Dec 2005
NH Summer
SCOUT-AMMA Aug 2006, Aug 2008
TRMM Radar: Frequency of Overshooting Precipitation Features (OPFs) at altitude > 14 km
Parts per thousand
(Liu and Zipser, 2005)

5. TRMM Lightning Imaging Sensor (LIS)
SH Summer
Hibiscus / Troccinox Feb 2004 and 2005
SCOUT Darwin Dec 2005
NH Summer
SCOUT-AMMA Aug 2006, Aug 2008
Lightning where vertical velocity is the fastest

6. WHERE ? Max Height Lightning
Yearly average percentage of TRMM extreme events in each 2-degree box
Zipser et al. 2006

7. How studying TST with balloons ?
1. Short flights as close as possible from storms

8. Rubber sounding balloons
SCOUT-AMMA
Niamey, Aug 2006, Aug 2008
1200 g balloons
Payload <5kg

9. Plastic sounding balloons
Hibiscus, Brazil Feb 2004
SCOUT -AMMA Niamey Aug 2006, Aug 2008 m3
Payload 5-30 kg

10. Small Zodiac ZL & SF balloons
Hibiscus, Brazil, Feb 2004
Scout-Amma
Aug 2006 m3
Several instruments
Total up to 120 kg
Light telemetry/ command

11. FIGHT STRATEGY
As close as possible from fast developping storms (few hours)
strong diurnal variation, unpredicted by NWP meteorological models
Now forecast only (GOES or MSG pictures, Radars in Bauru and Niamey)
High flexibility required : 2-3 hours max between decision and flight
MSG picture