Use of Satellite Earth Observations in Operational Meteorology

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Use of Satellite Earth Observations in
Operational Meteorology

• 1. The state of EO use in NWP
• 2. Challenges and current priorities
• 3. Suggestions for the next 5-10 years

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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1.a. Who are the users ?

• the big ones a few 'large' numerical weather
  prediction centres, with own satellite
  assimilation teams good contact with data
  providers (e.g. ECMWF)?
• many smaller institutes, with regional models
  growing modelling capability, but tiny RD teams
  de facto excluded from complex organisations.
• (some universities research centres
  increasingly work like small NWP centres)?

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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The big ones global forecast scores
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(No Transcript)
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1.b. What are their objectives ?

• to improve the overall forecast quality cf.
  scores
• to improve forecasts of high impact events
• to provide numerical input (or coupled model
  systems) for non-meteorological environmental
  models ocean, chemistry, hydrology, etc. 'Earth
  model'
• Subject to unpredictable trends in institutional
  strategies, fashion and funding opportunitites...

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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1.c. How is EO data used in NWP ?

• as direct input to data assimilation (DA)?
• as ancillary data
• for verification validation
• for research

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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EO use in direct assimilation

• Most visible application, but not the only one -
  and it's not limited to global models.
• a major factor of improvement over the past 20
  years - in synergy with increased CPU power new
  algorithms
• current DA algorithms (3D-Var and 4D-Var) were
  primarily developed for EO data assimilation
• impact of 'old' radiances (AMSU, HIRS) large,
  and still growing in quality coverage
• DA of new instruments (GPS, scatterometres,
  spectrometres...) will take several years to
  develop fully.

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Example of beneficial satellitedata
assimilation SEVIRI radiances into ALADIN
regional model
precipitation forecast errors (top
rms, bottombias)?
without SEVIRI
with SEVIRI
forecast range (hours)?
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Regional impact of EO is severely limited by
their coverage (which is global-model oriented)?
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EO use as ancillary NWP data

• these issues are neither 'pure' NWP nor
  adequately solved by other communities (yet)?
• they often suffer from chronic understaffing and
  lack of structuration (with lots of uncoordinated
  initiatives)
• orphan problems at many NWP centres
• sea surface, sea ice, sea roughness
• lake temperature/ice
• snow on ground
• sources of sand/dust
• soil moisture, soil temperature/ice,
  soil/vegetation properties
• surface properties for radiation computations...

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Mapping of microwave surface emissivity for
radiance data assimilation
SSM/I, 19V-19H
November 2006
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Importance of soil moistureT forecast from 2
models with slightly different soil analyses
T(C)?
truth
Time (hours over one day)?
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EO use for verification validation

• needed in quasi real time (for application to
  current NWP system versions)?
• verification bias correction, quality control,
  score computation, e.g. rarity of good
  precipitation data
• validation
• to check tune some non-assimilable model
  aspects e.g. radiation balance, cloud cover
• as  ground truth  in case studies, e.g. imagery

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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EO use for NWP research

• mostly to improve key physical parametrisations
  subgrid convection turbulence, radiation,
  microphysics, surface processes.
• useful datasets
• instrumented sites (ARM)?
• field experiments (IHOP, COPS, CSIP, RICO,
  IPY...)?
• research satellites (EOS, Aquatrain, Envisat)
• use of EO data is still incomplete, but
  promising.

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Challenges for NWP 1/4

• Different players may have different priorities
• NWP user How to sustain the current spectacular
  improvement in NWP thanks to EO
• Data provider How to improve the use of EO in
  NWP
• Meteorologist What are the key needs of NWP
• Manager How to improve cooperation between
  institutes

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Challenges for NWP 2/4

• How can we sustain the current spectacular
  improvement in NWP thanks to EO ?
• Keep flying existing technologies as long as they
  do not saturate the DA systems
• well known IR and microwave radiances,
  scatterometre, AMW winds, GPS, etc.
• emphasis on improved coverage, spatial
  resolution, repeat frequency, programme
  continuity, instrumental quality, stability of
  data dissemination.
• Not 'sexy', but very valuable - such data can be
  assimilated nearly as soon as an instrument
  flies. Coverage repeat frequency requirements
  are crucial for new mesoscale NWP DA systems.

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Challenges for NWP 3/4

• How can we improve the use of EO in NWP ?
• i.e. can we avoid EO data being underused by NWP
  ?
• Main reasons for NOT using EO data include
• short instrument lifespan (actual or expected)?
• lack of visibility on successor missions, and
  increases in coverage
• duplication with other instruments in terms of
  observed frequencies/regions/orbits etc)?
• lack of added value (low information content,
  difficulty to incorporate into NWP DA software)?
• may require excessive CPU or RD staffing

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Challenges for NWP 4/4

• The key needs
• 3D information on T, wind, Hu everywhere, with
  emphasis on dynamically sensitive areas and high
  impact weather.
• actual dx,dt resolutions of NWP DA systems
  global 50km x 6h, regional 5km x 1h.
• vertical resolution should be about 300m (!)?
• current T coverage is adequate in upper
  troposphere, often poor below (under cloud tops
  over land)?
• lack of precise (bias-free) humidity observations
• wind coverage is very poor (except on sea
  surface)?
• ancillary data see above, e.g. soil moisture.

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Quikscat limitation in heavy rain (useful anyway)?
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example of sensitive forecast structure(COPS
campaign thunderstorms)?
Cloudy area
Data-poor area
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3. Suggestions DA

• For 'hard' DA of EO data, the SAF-NWP (and ITWG)
  approach may be the best it is helpful
  cost-effective to have an interface team between
  data providers and NWP institutes.
• The core of DA is still done by NWP RD teams,
  which is not affordable to smaller institutes
  software interoperability (e.g. obs handling,
  monitoring) should be improved, perhaps by
  creating ad hoc teams.
• More perennial structuration is needed to
  facilitate access to ancillary data (esp. data
  fusion from various sources) e.g. GHRSST-PP is a
  good approach ? Is it cost-effective to tackle
  permanent problems using short-lived projects ?

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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3. Suggestions programmes

• Fact long-lived instrument concepts are much
  better used in NWP than high-tech, isolated ones.
• Because it is very difficult to enlarge NWP teams
  to feed new instrument technologies into DA
  systems.
• New versions of older instruments should focus on
  backwards compatibility, (orbit) complementarity,
  and global long-term continuity.
• Innovative instruments are welcome if they can be
  flight-tested quickly and (if ok) made
  operational with a long-term perspective.
• The prove there's an impact in NWP and then
  we'll fund it approach is very slow and
  unefficient. Weather obs. show a benefit after
  they are given good coverage, not before...

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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3. Suggestions organisation

• The SAF concept has worked very well.
• The European NWP consortia (COSMO, HIRLAM,
  AALDIN, MetOffice) and Eumetnet/SRNWP provide
  convenient opportunities to reach many NWP
  institutes and users.
• for directly assimilated data, the emphasis
  should be on spreading common expertise
  software for the NWP centres foster networking,
  training interoperable solutions. (avoid
  excessive meetings paperwork)?
• for ancillary data, the data merging can/should
  be done upstream by specific teams and freely
  distributed. Activities on a single instrument
  are of limited usefulness.

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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3. Suggestions 'from the trenches'

• according to NWP staff
• data from new satellites should be accessible
  earlier to DA scientists, even if the data is not
  perfect. It would speed things up.
• discussion with the data providers should be
  easier and more interactive. (the US-led mail
  forums are more productive)?
• instruments simultaneously flown on several
  satellites can be used quickly because it is
  faster to accumulate statistics about them.
• high opinion of SAF-type work organisation
• no time to work on DA of many interesting
  instruments because they are too unusual.

Globmodel workshop, 12 Sept 2007 - F. Bouttier
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Conclusions current NWP trends

• Emphasis on 'severe' weather events growing need
  for data about cloudy precipitating areas.
• Decreasing funding for RD teams only a limited
  variety of EO data types can be used. (but many
  satellites are ok)?
• High CPU data handling costs informativity may
  matter more than data quantity. High potential
  value of currently poorly observed regions and
  parameters (e.g. polar AMWs).
• Multiplication of smaller NWP institutes more
  demand for regional, high resolution high
  frequency EO data.

Globmodel workshop, 12 Sept 2007 - F. Bouttier