© Crown copyright Met Office Implementation of a new dynamical core in the Met Office Unified Model Andy Brown, Director of Science.
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© Crown copyright Met Office
Implementation of a new dynamical core in the Met Office Unified ModelAndy Brown, Director of Science
© Crown copyright Met Office
DePreSys
TIGGE ensemble
GloSea4
MOGREPS-Rensemble
Coupled atmos/ocean
Earth System
Timescale36hrs 48hrs 5 days 15 days 6 months 10 years 30 years >100 years
1.5km
4km
12km
24km
40km
80km
150km
300km
Comple
xity
UKV
UK4 NAE
Global
HadCM3
HadGEM1
HadGEM2
Global atmosphere-only
Regional atmosphere-only
HadGEM3-RA regional HadGEM3
Atmospheric grid length
© Crown copyright Met Office
A new dynamical core: ENDGame Atmos Physics 1
Advection
Atmos Physics 2
HelmholtzSolver
x2
x2
• Evolution of existing dynamics• Same equation set & variables• Same horizontal staggering (Arakawa C-grid)• Same vertical staggering (Charney-Phillips)• Iterative Semi-implicit semi-Lagrangian• Simpler solver• Less damping ( = 0.55)• Fully 3D advection for θ • Reformulated continuity equation
More scalable More stable More accurate
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Model changes alongside ENDGame
• Package of physics changes• ENDGame+physics=
• GA6.0 (climate)• GA6.1 (weather)• GA6.0 and 6.1 extremely similar (more seamless than
ever)
• For global NWP• Model N512 (≈25km) → N768 (≈17km) • 4D-Var inner loop N216 (≈60km) → N320 (≈40km) • Satellite package
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Eddy Kinetic EnergyT+72hr EKE from 10 x ECMWF cases
Paul Earnshaw
9.0
7.0N96 N216 N512 N768
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Extra-tropical circulationEquivalent plots from PS32-based trials
See poster by David Walters
July
201
2
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Tropical circulationSignificant increases in variability
Equatorial precip frequency/wavenumber spectrum from 20yr climate runs:
Prince Xavier
GA4.0GA6.0TRMM obs
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Tropical circulation Major improvements in Tropical Cyclone forecasts
Impact of science upgradeN512 GA6.1 vs N512 GA3.1
Impact of science + resol’nN768 GA6.1 vs N512 GA3.1
Mean abs. PMSL error reduction 3.0 hPa 3.6 hPa
Central pressure reduction 7.1 hPa 11.1 hPa
Mean abs. |v| error reductions 6.7 kt 9.0 kt
Mean max. |v| increase 8.9 kt 13.4 kt
850hPa vorticity increase 79% 155%
Track error reduction 7.3% 8.6%*
Track skill score increase 3.8% 4.5%
Julian Heming, Keith Williams
* Biggest reduction in TC track error in a single UM upgrade for 20 years!
Average impacts from PS32-based trials:
© Crown copyright Met Office
New global versus 12km regional model
Surface weather impacts(Temperature, cloud cover, cloud base, ppn, visibility)
New global versus old global
Significant improvement in near-surface weather measures
Global outperforms 12km Limited Area Model – now retired
Global significantly behind 1.5km model for UK
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Outgoing SW radiation
New New minus Old
Old minus climatology New minus climatology
Dan Copsey
© Crown copyright Met Office
Kilometre-scale modellingCloser to a centred semi-implicit approach
Impact in UKV Lee Wave test: New DynamicsENDGame
Simon Vosper
© Crown copyright Met Office
DePreSys
TIGGE ensemble
GloSea4
MOGREPS-Rensemble
Coupled atmos/ocean
Earth System
Timescale36hrs 48hrs 5 days 15 days 6 months 10 years 30 years >100 years
1.5km
4km
12km
24km
40km
80km
150km
300km
Comple
xity
UKV
UK4 NAE
Global
HadCM3
HadGEM1
HadGEM2
Global atmosphere-only
Regional atmosphere-only
HadGEM3-RA regional HadGEM3
Atmospheric grid length
Dynamics matters!
Extremely significant model upgradeachieved in seamless framework
© Crown copyright Met Office
Physics changes
Significant physics differences between GA3.1 and GA6.1:
Total of 66 tickets (including ENDGame) in GA4, GA5 and GA6
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