The use of satellite data has the potential to significantly improve weather forecasts.

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The use of satellite data has the potential to
significantly improve weather forecasts.

• NWP models needs knowledge of the state of the
  atmosphere and surface.
• Satellites provide an excellent avenue to acquire
  global data using the same suite of instruments.
• Future significant improvements in weather
  prediction need significant improvements in the
  accuracy of satellite products.

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Improved product accuracy will be achieved with
new advanced infrared sounders

• Current low spectral resolution sounders, with
  relatively few spectral bands, are being phased
  out by advanced high spectral resolution infrared
  sounders with thousands of narrow spectral bands
  (channels).
• The Atmospheric Infrared Sounder (2002) will be
  the first high spectral resolution infrared
  sounder to be used routinely in numerical weather
  forecasting.
• AIRS will be followed by CrIS and IASI (both
  2006)

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Spectral coverage of AIRS, IASI and CrIS
Number of channels
2378
AIRS
IASI
8461
IASI
8461
19 HIRS Channels
1300
CrIS
CrIS
1300
500 1000
1500 2000
2500 3000
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Each channel has a weighting function
With one channel the retrieval is the observed
brightness temperature which can be thought of as
deep-layer mean temperature. The layer is
defined by the weighting function. Need many
overlapping weighting functions to derive an
accurate pointwise temperature profile.
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Benefits of high spectral resolution

• Improved spectral resolution results in
• Sharper weighting functions
• Clean channels (e.g. temperature channels
  not contaminated by water vapor lines)
• Many channels with sharp weighting functions
  combined with low noise improves vertical
  resolution
• Retrieval accuracy is greatly improved
• (atmospheric temperature , moisture , ozone,
  skin temperature and surface emissivity)

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More channels low instrumental noise
better retrievals
AIRS temperature Weighting functions
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Temperature and moisture retrieval accuracy from
AIRS is much improved when compared to
current operational sounder ATOVS
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AIRS Real-Time Products from NESDIS

• Clear and cloud-cleared radiance datasets for
  direct assimilation of radiances.
• Full resolution retrievals for assimilation of
  retrievals.
• Users - NCEP, ECMWF, Goddard DAO,
  Meteorological Service of Canada , Met. Office,
  and Meteo France
• Products based on real-time simulations are now
  available

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Example of simulated AIRS window channels LW,
SW



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• For additional information on AIRS and
  availability of AIRS products in near real-time
  contact Mitch Goldberg
• Mitch.Goldberg_at_NOAA.GOV