Deterministic models assimilating RO
- Global model (ARPEGE):
- Spectral model T798C2.4
- 70 vertical levels from 17m to 0.05 hPa.
- Run four times per day: 102H at 00 UTC, 72H at 06 UTC, 84H at 12 UTC, 60H at 18 UTC.
- Limited area model (ALADIN):
- Resolution 7.5km
- 70 vertical levels (same as for the global model)
- Run four times per day: 54H at 00 UTC, 48H at 06 UTC, 42H at 12UTC, 36H at 18 UTC.
- Cutoff times:
- Synoptic time:
- 00UTC
- 06UTC
- 12UTC
- 18UTC
- Standard run:
- 2h15
- 3h00
- 1h50
- 3h00
- Update run:
- 8h00
- 6h55
- 8h05
- 7h15
- Synoptic time:
Data assimilation method
- Global model:
- 4D VAR with a 6-hour time window (T+-3h)
- Limited area model:
- 3D-VAR with a 6-hour time window (T+-3h)
RO quantity assimilated
- Bending angle
- 1D operator
- Tangent point drift included
- Vertical thinning: none – removing it improved FSO scores
- No bias correction
Observation error characteristics
- 5.4% of observed value near the surface decreasing linearly to 1.8% at 10km high, 1.8 % between 10 and 15 km, 2.7% from 15 to 46km
- An absolute minimum bending angle error of 3 micro radians
Impact
The impact and impact per observation computed with the FSO tool over 1 month in September 2013, with the operational model:
