Use of AMVs in the Environment Canada model
- 1 Use of AMVs in the Environment Canada model
- Grid-point model 2x1287x417 Yin-Yang horizontal grid
- Horizontal resolution: ~25 km
- Vertical resolution: 80 levels, model top 0.1 hPa
Data assimilation method
- 4D-EnVar, 6-h assimilation window, 4DIAU, 0.33° x 0.33° increment resolution
- Time window: T ± 3 hr, analysis times (T): 00, 06, 12, 18 Z
- Time constraints (model runtime):
- Early analysis and forecast run: T+3 hr, forecast at 00 and 12Z only
- Update analysis run: ~T+9 hr at 00 and 12Z, T+6 hr at 06 and 18Z
25 time bins in the 6-h assimilation window.
AMV types assimilated
- Meteosat-11 IR, VIS, WV
- Meteosat-8 IR, VIS, WV
- GOES-15 IR 3.9 IR 10.7, VIS, WV
- NESDIS MODIS Terra IR, WV
- NESDIS MODIS Aqua IR, WV
- direct broadcast MODIS from Tromso, Fairbanks and McMurdo
- AVHRR NOAA-15/18/19 IR
- EUMETSAT Single Metop-A/B IR
- EUMETSAT Dual-Metop IR
- NPP IR
- Himawari-8/9 IR, VIS, WV 6.9
Global quality control
Blacklisting in space
- All geostationary winds beyond 68° satellite zenith angle
- All winds above 200 hPa (160 hPa over the Tropics)
- All winds below 1000 hPa (400 hPa over land)
- All VIS winds above 700 hPa
- All geostationary WV winds below 400 hPa
- All Meteosat-11, Meteosat-8 and Himawari-8/9 winds over land north of 25N, south of 20S and below 400 hPa
- All GOES winds over land north of 20N, south of 20S and below 400 hPa
- All polar WV winds below 550 hPa
- All polar IR winds below 700 hPa
- All polar winds over land below 400 hPa
- All Dual Metop outside the latitude bands 40-60 N/S
- All wind speeds below 2.5 m/s
Note: There are no QI thresholds applied to the polar winds except EUMETSAT Single Metop and Dual Metop (QI1>80)
extratropics: polewards of 20S/N
hl: 10-400 hPa
ml: 400-700 hPa
ll: 700-1000 hPa
QI1 – EUMETSAT QI with first guess check
QI2 – EUMETSAT QI without first guess check
RFF – Recursive Filter Function (CIMSS/NESDIS)
For information on how the quality indicators are formulated see Holmlund (1998, Weather Forecasting 13 1093-1104) and Hayden and Purser (1995, Journal of Applied Meteorology 34 3-15).
- The AMV are first sorted according to their quality index (QI1) from highest to lowest on 10 layers.
- For each satellite, the selection process starts from the AMV with the highest QI1.
- The next AMV is selected if all previous selected data in the same layer and within 6 time bins (1h30) are beyond 200 km.
- The selection process is repeated for all subsequent AMVs.
The background check is applied to the vector difference between the AMV and the corresponding background value. A variational quality control is then applied on each wind component during the minimization.
Similar to Met Office – observation errors calculated individually for each wind using estimates of the error in vector, error in height and variation in the background wind column.