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AMV usage in the Met Office NWP model

Last updated Mar 2014

Back to use in NWP table

Physical characteristics
  • Grid-point model (1024 E-W x 769 N-S)
  • Horizontal resolution: 0.35 x 0.23 degrees
  • Vertical resolution: 70 vertical levels, hybrid-eta configuration
Data assimilation method
  • 4D-Var, 6 hr time window
  • Time window: T ± 3 hr, analysis times (T): 00, 06, 12, 18 Z
  • Time constraints (model runtime):
    • Main forecast run: 20 min before time window ends
    • Update run: 3 hr 15 min after time window ends
AMV types assimilated
  • Meteosat-10 IR, cloudy WV 7.3, VIS and HRVIS
  • Meteosat-7 IR, VIS, cloudy WV
  • MTSAT-2 IR, VIS, cloudy WV
  • GOES-15 IR, cloudy WV
  • GOES-13 IR, cloudy WV
  • NESDIS and direct broadcast Terra IR
  • NESDIS and direct broadcast Aqua IR, cloudy WV, clear sky WV
  • CIMSS and direct broadcast NOAA-16 IR
  • CIMSS and direct broadcast NOAA-18 IR
  • CIMSS and direct broadcast NOAA-19 IR
  • CIMSS Metop-A IR
  • CIMSS Metop-B IR
Quality Control
Blacklisting in space
  • All geostationary winds beyond 68° satellite zenith angle
  • All winds reporting in height at or above 160 hPa and all extratropical (polewards of 20N/S) winds above 200 hPa
  • All VIS winds at 700 hPa and above
  • Meteosat-7 WV below 400 hPa in extratropics (polewards of 30N/S) and below 280 hPa in tropics
  • MSG WV below 400 hPa, MTSAT-2 WV below 300 hPa, GOES WV below 400 hPa
  • All polar WV and CSWV winds below 600 hPa
  • All Meteosat-7 and MSG winds below 500 hPa and 600 hPa respectively over land north of O degrees
  • All MTSAT and GOES winds below 600 hPa over land north of 20N
  • All polar winds below 600 hPa over land and sea ice
  • All polar winds below 400 hPa over Greenland and Antarctica
  • Low-mid level winds dependent on topography
  • All AVHRR polar winds at or above 350 hPa in SH
  • All daytime MTSAT IR below 700 hPa
  • Seasonal rejection of MTSAT IR winds in NH jet region: above 400 hPa north of 20N (applied approx Dec-Feb).
  • Seasonal rejection of Meteosat-7 IR winds in SH jet region: above 600 hPa south of 40S (applied SH winter).
  • MSG IR below 600 hPa in the Mediterranean, Red Sea and Gulf
  • MSG VIS and IR below 600 hPa over sea near Guinea
  • GOES below 500 hPa assigned using CO2 slicing method
  • All geostationary below 400 hPa assigned using WV intercept method
QI thresholds
No QI thresholds applied to the polar data.

  extratropics tropics
Meteosat-7/10 QI1 IR 85 80 80 90 90 90
VIS - - 65 - - 90
WV 80 - - 90 - -
GOES-15/13 QI1 IR 85 80 80 90 90 90
WV 80 - - 90 - -
MTSAT-2 QI1 ALL 85 85 85 85 85 85

tropics: 20S-20N
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).

  • All geostationary winds thinned in 2° by 2° by 100 hPa boxes.
  • All polar winds thinned in 200 km by 200 km by 100 hPa boxes.
  • Wind selected by lowest error for all geostationary winds
  • Wind selected by closest to centre of box for all polar winds.
  • Assimilated in 2-hour time slots
Background check
  • Background check: comparison with 6-hour forecast from previous model run (asymmetric adjustment removed)
Observation errors

Observation errors calculated individually for each wind using estimates of the error in vector, error in height and variation in the background wind column. For more information see AMV errors: a new approach in NWP (9IWW paper).

The mean profile and zonal plots in the table below give an indication of the typical observation errors used. Statistics calculated for June 2012 with QI2 > 80.

satellite NH TR SH Zonal

History of Changes
The list includes the main AMV or model changes implemented operationally in the Met Office global model.

21/01/14 Reinstate low level MSG winds.
19/02/13 Start assimilating CIMSS MetOp-B AVHRR polar winds.
21/01/13 Switch from Meteosat-9 to Meteosat-10 winds.
16/01/13 Remove temporal blacklisting and implement 2-hour temporal thinning (PS31)
09/10/12 Blacklist all low level MSG winds
13/12/11 Switch from GOES-11 to GOES-15 winds.
20/07/11 Revision to AMV height errors and spatial blacklisting (PS27).
15/02/11 Start assimilating CIMSS MetOp-A AVHRR polar winds.
11/08/10 Switch from MTSAT-1R to MTSAT-2 winds.
20/04/10 Switch from GOES-12 to GOES-13 winds.
09/03/10 Global model resolution upgrade to 25 km.
16/02/10 Start assimilating NOAA-19 and direct broadcast polar winds from Sodankyla, Fairbanks, Barrow and Rothera.
10/11/09 Changes to AMV background check, vertical resolution upgrade from 50 to 70 levels.
23/07/08 Switch to new observation error scheme.
20/05/08 Start assimilating NOAA 15-18 AVHRR polar winds.
17/04/07 Switch from Meteosat-8 to Meteosat-9.
06/03/07 Switch from MTSAT-1R SATOB to BUFR.
13/12/06 Replaced Meteosat-5 with Meteosat-7 and started assimilating the MODIS direct broadcast winds from Tromso and McMurdo Station.
18/07/06 Switch from GOES-10 to GOES-11 winds.
14/03/06 Switch from Meteosat-7 to Meteosat-8 winds.
13/12/05 Global model resolution upgrade to 40 km, 50 levels.
01/09/05 Start using MTSAT-1R SATOB winds (after removal of GOES-9).
14/06/05 Switch from GOES-10/12 IR satob to GOES-10/12 IR and cloudy WV BUFR winds
08/02/05 Use of NESDIS MODIS Terra and Aqua winds.
05/10/04 4D-Var replaces 3D-Var
20/01/04 Blacklist high level extratropical GOES-9 IR winds
08/07/03 Start using GOES-9 winds (after removal of GMS-5)
19/05/03 Start using GOES-12 winds (after removal of GOES-8)
11/12/02 Switch from Meteosat SATOB to BUFR
Aug 02 New dynamical core for UM
17/10/01 Updated satwind observation errors.