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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 l.jpg

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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg

  • 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 l.jpg
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 l.jpg
Research experiments with HIRS data

  • 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 l.jpg
Forecast scores (rms & bias) over Europe data with 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 l.jpg
Results of last experiments with HIRS data

  • 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 l.jpg
Assimilation of Meteosat data 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


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Assimilation of Meteosat data 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 l.jpg
Meteosat 5&7 observation fit to first guess and analysis data area=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 l.jpg
Present time, near/next future data

… 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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