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Use of satellite data at Météo-France. Élisabeth Gérard Météo-France/CNRM/GMAP/OBS, Toulouse, France on behalf of: É. Gérard, F. Rabier, N. Fourrié and D. Lacroix (ATOVS) C. Payan and F. Rabier (Météosat). ATOVS data. Operational implementation of

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use of satellite data at m t o france

Use of satellite data at Météo-France

Élisabeth Gérard

Météo-France/CNRM/GMAP/OBS, Toulouse, France

on behalf of:

É. Gérard, F. Rabier, N. Fourrié and D. Lacroix (ATOVS)

C. Payan and F. Rabier (Météosat)

25thEWGLAM/10thSRNWP

Lisbon, Portugal

6-9 October 2003

atovs data
ATOVS data
  • Operational implementation of
    • Raw radiances instead of preprocessed radiances: 22 October 2002 (+ European & American profilers)
    • NOAA17 on top of NOAA15 & NOAA16: 17 December 2002
    • AMSUA data only in operations
  • AMSUA data denial experiments (OSEs)
  • Research experiments with locally received data
    • Lannion/EARS in addition to Nesdis/Bracknell
  • Research experiments with HIRS

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

raw radiances instead of preprocessed radiances
Raw radiances instead of preprocessed radiances
  • No more 1DVar pre-processing
    • Ts in the control variable
    • Extrapolation above the top of the model (1 hPa) up to 0.1 hPa by regression
    • « Rain contamination » test
      • observation rejected if |obs-guess|channel 4 > 1.5 K
  • 250 km thinning
  • Data coverage more regular, less missing orbits, less scan border pixel removal
  • Use of more channels over land

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

raw radiances instead of preprocessed radiances4
Raw radiances instead of preprocessed radiances

Time series of rms errors and biases

24 hour forecast 200 hPa geopotential scores over 1 month 22 Aug - 22 Sep 2002

Northern Hemisphere

Southern Hemisphere

scores computed wrt their own analysis

Preprocessed radiances

Raw radiances

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

amsua data denial experiments
AMSUA data denial experiments
  • Uniform (unstretched) ARPEGE:
    • 4DVar analysis T107C1L41 (up to 1hPa)
    • Forecast T359C1L41 with 1800 s time step
  • Experiments with and without AMSUA data: 23 Dec 2002  12 Jan 2003
  • One forecast a day from 00 UTC analysis:
    • Short cut-off time: 03h50 (production)
    • Long cut-off time: 09h55 (assimilation)
  • Impact of AMSUA data wrt cut-off time

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

benefit of amsua data
Benefit of AMSUA data

Time series of rms errors and biases

24 hour forecast 500 hPa geopotential scores over 3 weeks 23 Dec 2002 - 12 Jan 2003

Northern Hemisphere

rms difference

scores wrt long cut-off analysis with AMSUA data

Southern Hemisphere

With AMSUA (long cut-off)

Without AMSUA

rms difference

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

amsua data denial experiments7
AMSUA data denial experiments
  • Positive impact of using AMSUA data
  • More pronounced benefit
    • over Southern Hemisphere than Northern Hemisphere,
    • over North America than Europe,
    • when cut-off time is long
  • Increase of gain with forecast range more regular with long cut-off time over North America (more robust signal)
  • When AMSUA data are used, more gain wrt cut-off time is expected if short cut-off time is shorter (i.e. 1h50 @ 00 UTC in oper stretched ARPEGE model)

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

research experiments with locally received amsua data

EARS data

  • Eumetsat ATOVS Retransmission Service
  • Data rapidly available
  • No blind orbit for NOAA17
  • (reception centres: Greenland, Norway, Canary Islands)
Research experiments with locally received AMSUA data

13 March 2003 12 UTC

Data available for the operational production, 1h50 cut-off time

Nesdis/Bracknell data

  • Lannion data 45W/40E/70N/30N
  • Even more rapidly available, but smaller area & only NOAA16/NOAA17

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

impact of ears and lannion data in addition to bracknell data rms bias wrt radiosondes
Impact of EARS and Lannion data in addition to Bracknell data (rms/bias wrt radiosondes)

Temperature @ 250 hPa

forecast range (hour)

12

36

48

BracknellBracknell+EARS+Lannion

First step: assimilation in operational model ARPEGE

Next step: assimilation in regional model ALADIN (… AROME) in research mode

AMSUA, HIRS, AMSUB (observation density, bias correction, …)

research experiments with hirs
Research experiments with HIRS
  • On top of AMSUA data over 23 Dec 2002 – 12 Jan 2003
  • 250 km thinning (as for AMSUA)
  • Cloud contamination test with channel 8
      • rejection if x < obs-guess < y, (x,y)=f(latitude)

water vapour channels

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

forecast scores rms bias over europe with hirs without hirs
Forecast scores (rms & bias) over Europewith HIRSwithout HIRS

scores computed wrt own analysis

24 hour

48 hour

72 hour

forecast range 

geopotential

temperature

wind

rel. humidity

results of last experiments with hirs
Results of last experiments with HIRS
  • Occurrence of « ringing » problem in stratosphere this summer
    • channels 5, 6, 7, 14, 15 blacklisted over seaice
    • channels 4 & 15 (tail up to 1hPa) to be blacklisted ?
    • only channels 11 & 12 to be assimilated ?
    • Cloud contamination test to be revised ?
    • First guess check to be revised ?

(obs-guess)2 <(o2+b2)

… under investigation …

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

assimilation of meteosat data
Assimilation of Meteosat data

Use of BUFR winds produced by EUMETSAT with a quality index and disseminated every 90 minutes

compared to

Use of currently operational SATOB winds produced every 6 hours

… as a preparation towards the use of other geostationary satellite data (GOES, etc.)…

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

assimilation of meteosat data14
Assimilation of Meteosat data
  • Experiments with the uniform ARPEGE configuration
  • 23 Dec 2002 - 12 Jan 2003
  • SATOB winds
    • Only data with QI>0.8 are transmitted
  • BUFR winds conditional use
    • Weak constraint: QI>0.6 for upper level winds and over sea for mid-level winds
    • Strong constraint: QI>0.8-0.9 elsewhere as a function of latitude, level, channel Vis/IR/mw

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

meteosat 5 7 observation fit to first guess and analysis area 50n 50s 113e 50w
Meteosat 5&7 observation fit to first guess and analysisarea=50N/50S/113E/50W

Used U component

  • BUFR versus SATOB
  • more data used
  • rms and bias reduction

Used V component

present time near next future
Present time, near/next future

… for satellite observations…

  • Tuning of AMSUA data: density, rain detection
  • HIRS use, cloud detection, obs error tuning, blacklist
  • ATOVS bias correction wrt analysis (?)
  • Assimilation of BUFR winds on going
  • AIRS: screening, bias correction already performed, first assimilation experiments on going

Next future: AMSUB, SeaWinds, MSG, MODIS, SSM/I(S)

25thEWGLAM/10thSRNWP, Lisbon, Portugal, 6-9 October 2003

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