1. Vertical diffusion in ERA-40 Dirk Olivié 12 November 2003 Vertical diffusion in ERA-40

2. Overview Vertical Diffusion Louis, Holtslag, ECMW6h –K z –profile –Radon distribution –Comparison with measurements Ecmwf3h, Ecmwf6h –Radon distribution –Comparison with measurements

3. What it’s all about … K z : diffusion coefficient [m 2 s -1 ] C : tracer concentration

4. Overview diffusion data time step Louis6h00instantaneous Holtslag3h00instantaneous Ecmwf-6h6h00accumulated Ecmwf-3h3h00accumulated

5. Louis – Holtslag – ECMWF6h K z profile Global Radon distribution Comparison with Radon measurement –daily cycle –correlation

6. K z : mean profile Louis Holtslag Ecmwf-6h August 1993 Global mean Over land

7. K z : daily cycle Louis Holtslag Ecmwf-6h 4h307h3010h30 13h3016h3019h3021h30 1h30

8. Radon : Holtslag - Louis

9. Radon : Ecmwf6h - Holtslag

10. Radon : Ecmwf6h - Louis

11. Radon : Surface Louis Holtslag Ecmwf-6h Measurement

12. Radon : 1200 m Louis Ecmwf-6hMeasurement HoltslagNo diffusion

13. Correlation : surface Jan Mar May Jul Sep Nov Louis Holtslag Ecmwf-6h

14. Correlation : 1200 m Louis Holtslag Ecmwf-6h Jan Mar May Jul Sep Nov

15. ECMWF3h-ECMWF6h Global Radon distribution Daily cycle Correlation

16. ECMWF3h-ECMWF6h

17. Radon - Daily cycle - surface Louis Holtslag Ecmwf-6h Ecmwf-3h Measurement

18. Radon - Daily cycle – 1200 m Louis Holtslag Ecmwf-6h Ecmwf-3h No diffusion Measurement

19. Correlation surface Jun Jul Aug Louis Holtslag Ecmwf-6h Ecmwf-3h No diffusion

20. Correlation : 1200 m Louis Holtslag Ecmwf-6h Ecmwf-3h No diffusion Jun Jul Aug

21. Radon profile Louis Holtslag Ecmwf-6h Ecmwf-3h No diffusion