CAMM model performance assessed during DODO 2 Steph

Description of the CAMM: §Non-hydrostatic §Two-time level semi-implicit semi. Lagrangian scheme §Charney-Philips staggering in

Description of the CAMM: § Domain: - § Resolution: 0. 18°x 0. 18° resolution

Description of the dust scheme: § Dust scheme based on Woodward (2001) § 6

Description of the dust optical properties: § Mie scattering § Spherical particles § 6

Modifications when moving from climate model: § Soil data set in climate model -

Additional modifications: § The threshold friction velocities were reduced by 0. 15 ms-1 and

CASE STUDY – AUG 23 rd Met Office © Crown copyright 2007 Page 8

The dust forecast from the 21 st August Met Office © Crown copyright 2007

The dust forecast from the 21 st August Tropical storm Debbie Dust storm within

A t+9 forecast: Tropical storm Debbie Dust storm within range of BAe 146 Met

The problems of model validation are shown by the MISR coverage: Met Office ©

Therefore correlative methods of MISR-OMI are developed (Christopher et al): Met Office © Crown

Met Office © Crown copyright 2007 Page 16

Comparison of dust event with Dakar AERONET Met Office © Crown copyright 2007 Page

Flight pattern on the 23 rd August 2006 Met Office © Crown copyright 2007

MONTHLY MEAN COMPARISONS Met Office © Crown copyright 2007 Page 20

Can also look at the monthly means: Met Office © Crown copyright 2007 Page

Monthly mean comparisons: Met Office © Crown copyright 2007 Page 22

AERONET monthly means: Met Office © Crown copyright 2007 Page 23

Conclusions: Case study: § The CAMM model shows SKILL up to (and beyond? )

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CAMM model performance assessed during DODO 2 Steph Woodward – climate model dust scheme Glenn Greed – implementation of dust in the CAMM model – Running of operational forecasts for use in DODO 2 flight planning Mark Harrison – NAME model forecasts Jim Haywood – Analysis of aircraft data Sundar Christopher – Satellite retrievals/validation Met Office © Crown copyright 2007 Page 1

Description of the CAMM: §Non-hydrostatic §Two-time level semi-implicit semi. Lagrangian scheme §Charney-Philips staggering in the vertical §Arakawa C grid in the horizontal §Data assimilation (4 -D var) satellite, sonde, surface, and data from commercial aircraft Met Office © Crown copyright 2007 Page 2

Description of the dust scheme: § Dust scheme based on Woodward (2001) § 6 size bins in the range 0. 03 -30μm radius § Dust emission is based on the scheme by Marticorena and Bergametti (1995) § Dust flux a function of: clay, silt, and sand fraction, vegetative fraction, soil moisture, friction velocity threshold, and surface layer friction velocity. § Convection, turbulent mixing, gravitational settling accounted for § Dry and wet deposition Met Office © Crown copyright 2007 Page 4

Description of the dust optical properties: § Mie scattering § Spherical particles § 6 -wavebands in the solar spectrum § 9 - wavebands in the long-wave § AOD diagnostic developed at 0. 55μm Met Office © Crown copyright 2007 Page 5

Modifications when moving from climate model: § Soil data set in climate model - Wilson and Henderson-Sellers (1985) at 3. 75 o replaced by International Geosphere Biosphere Programme (IGBP, Loveland Belward, 1998) at 1 kmx 1 km. Met Office © Crown copyright 2007 Page 6

Additional modifications: § The threshold friction velocities were reduced by 0. 15 ms-1 and is now defined for all particle sizes spanning 0. 06 to 2000μm diameter (rather than 0. 06 to 60μm as in W 2001). § Horizontal dust flux calculations now include sand particles. The vertical flux is still assumed to consist only of particles between. 06 and 60μm. § A correction to the dust uplift code have also been introduced which inhibits emissions of dust from steep slopes. Met Office © Crown copyright 2007 Page 7

Conclusions: Case study: § The CAMM model shows SKILL up to (and beyond? ) 42 hours. § The horizontal position and vertical extent of the dust is well represented § The optical depth is reasonably well represented Monthly means: § The OMI/MISR comparisons show a reasonable agreement § AERONET shows a reasonable agreement Met Office © Crown copyright 2007 Page 24