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Development of the deterministic forecast system (June 2006). Martin Miller (Head of Model Division) with input from many colleagues. Operational changes from June 2004 up to June 2005 (the last User Meeting). 29 June 2004 – Early Delivery System 28 September 2004 – IFS cycle 28r3
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(Head of Model Division)
with input from many colleagues
Anomaly correlation of 500hPa forecasts for Europe
Mean from 1 Dec 2004 to 28 June 2005
Track forecasts from 12 UTC 11 Aug 2004
Comparison of cycle 29r2
e-suite and operations
with independent TCWV retrievals from Jason
Global 1.74 1.90
N. Hemisphere 1.63 1.71
Tropics 2.12 2.43
S. Hemisphere 1.53 1.62
N. Atlantic 1.63 1.69
N. Pacific 1.57 1.69
Assimilation of rain-affected microwave radiances
and improvement of humidity analysis
Mean sea-ice concentration 5 - 24 January 2004
- Use of grid-point humidity and ozone
- Revised ozone chemistry
Position of levels and pressure layer thickness of L60 (blue) and L91 (red)
L60Vertical Resolution Increase
increased from 60 to 91.
V-wind in NH extra-tropics
Green numbers: T799L91 better than T511L60,red numbers: T799L91 is worse
27th 00UTC 2.5 days
This upgraded forecasting system provides:
Applied statically, but derived from variational scheme to be implemented with cycle 31r1
Sonde-bg New bias correction
Sonde-an New bias correction
RMS error of 300hPa tropical temperature forecasts
New bias correction
Mean from 8-31 Jan 2006
31r1 – 30r1 annual mean difference
Largest changes in the tropical upper troposphere
CY31R1: New vegetation roughness + turbulent orographic form drag scheme (TOFD)
Examples of orographic spectra from 100m data over the USA
Measure spectral amplitude from 1 km data.
Extrapolate spectrum by making assumption about power law.
Smaller drag coefficients: diff stress/wind(level48)^2
Higher 10m wind
Without stochastic physics
With stochastic physics
Only this height is used to excite gravity waves.
Lott and Miller 1997
T511 average vertically integrated zonal wind error from 96h CY29R1 forecasts from 12Z on each day of January 2005 using the new turbulent orographic drag scheme and cutoff mountain.
1D-Var Performance Mean TCWV Increments Mean TCWV Increments
>0: CY30R2 better
<0: CY31R1 better
(August 2005, T511L60)
And over course of the year: