1. Convective intensification induced by a descending dry layer: a case study of CSIP IOP 9 Andrew Russell and Geraint Vaughan Centre for Atmospheric Sciences University of Manchester

2. 1. CSIP – The Convective Storm Initiation Project

3. CSIP observational campaign was a collaborative project United Kingdom Universities of: * Reading * Leeds * Manchester * Salford * Bath The Met Office Chilbolton Observatory Germany Institut für Meteorologie und Klimaforschung (IMK), Karlsruhe Universität Braunschweig GeoForschungsZentrum, Potsdam Courtesy of Cyril Morcrette

5. 2. Synoptic Background

6. 1645 UTC Rainfall radar IOP9: 18th July 2005

7. 1645 UTC MSG visible IOP9: 18th July 2005

8. 1530 UTC CAMRa 3GHz IOP9: 18th July 2005

9. MSG visibleMSG WV ECMWF PVTOMS O 3 1200 UTC

10. MSG visibleMSG WV ECMWF PVTOMS O 3 1200 UTC

11. MSG visibleMSG WV ECMWF PVTOMS O 3 1200 UTC

12. MSG visibleMSG WV ECMWF PVTOMS O 3 1200 UTC

13. 3. Observations of the dry layer

15. GPS Water Vapour - Linkenholt θ w (ºC) and 10% Relative Humidity (RH) from Radiosondes - Swanage SNR from wind profiling radar – Linkenholt (plotted over Swanage sonde data)

16. IOP9: 18 th July 2005 1645 UTC

17. LID θw decreases with height… … instability!

20. 3. How the convection was forced

21. 1600 UTC

22. MSG visibleMSG WV ECMWF PVTOMS O 3 1200 UTC

23. ECMWF RH (shading) and T (contours)

24. 1200 UTC ECMWF PV (shading and contours) and θ (dashed contours)

28. For more thoughts on the upper- level origin of atmospheric lids, see my poster…

29. 4. Conclusions Convective showers over southern England behind a cold front Dry intrusion overran moist surface layer resulting in potential instability Convection capped at 6 km by uppermost dry layer Interesting observations of the double descending layer, which had a role in both forcing and inhibiting the convection Andrew Russell Centre for Atmospheric Sciences University of Manchester andrew.russell-2@manchester.ac.uk www.andrewrussell.co.uk