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

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

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

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

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

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

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

Radon : Holtslag - Louis

Radon : Ecmwf6h - Holtslag

Radon : Ecmwf6h - Louis

Radon : Surface Louis Holtslag Ecmwf-6h Measurement

Radon : 1200 m Louis Ecmwf-6hMeasurement HoltslagNo diffusion

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

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

ECMWF3h-ECMWF6h Global Radon distribution Daily cycle Correlation

ECMWF3h-ECMWF6h

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

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

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

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

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