Comparisons between GOES and LEO hyperspectral
IR soundings over CONUS
Jun Li#, Elisabeth Weisz#, Tim Schmit@, Jim Nelson#,
Jinlong Li#, Hui Liu& and Zhenglong Li#
#Cooperative Institute for Meteorological Satellite Studies
University of Wisconsin-Madison
1225 West Dayton Street
Madison, WI 53706
@Center for Satellite Applications and Research
NESDIS/NOAA
&National Center for Atmospheric Research
Supported by GOES-R Program Office
16th Conference on Satellite Meteorology and Oceanography
Phoenix, AZ, 12 – 15 January 2009
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Outline
ƒ GOES Sounder data and applications
ƒ Sounding comparisons between GOES and
AIRS
ƒ Why hyperspectral IR sounder on GOES
satellite ?
ƒ Demonstration of GEO hyperspectral IR
sounder and applications
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T – WFs
Advanced
Sounder
T -WFs
GOES
Sounder
W – WFs
Advanced
Sounder
W –WFs
GOES
Sounder
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Low vs High Spectral Resolution
The current GOES Sounder has only 18 IR spectral data points, while a high
spectral resolution sounder may have between 800 and 8000 spectral points.
The broad-band nature of the current GOES limits the vertical resolution.
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Spectral coverage (18 IR + 1 Visible band) for current GOES Sounder
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Current Sounder Operational Uses
GOES Sounder Product
Operational Use within the NWS
Clear-sky Radiances
Assimilation into NCEP operational regional & global NWP
models over water
Layer & Total Precipitable Water
Assimilation into NCEP operational regional & global NWP
models; display and animation within NWS AWIPS for use
by forecasters at NWS WFOs & National Centers in
forecasting precipitation and severe weather
Cloud-top retrievals (pressure,
temperature, cloud amount)
Real Time Mesoscale Analysis
(RTMA)
Assimilation into NCEP operational regional NWP models;
display and animation within NWS AWIPS for use by
forecasters at NWS WFOs; supplement to NWS/ASOS
cloud measurements for generation of total cloud cover
product at NWS/ASOS sites
Surface skin temperature
Image display and animation within NWS AWIPS for use by
forecasters at NWS WFOs
Profiles of temperature & moisture Display (SKEW-Ts) within NWS AWIPS for use by forecasters
at NWS WFOs in forecasting precipitation and severe
weather
Atmospheric stability indices
Image display and animation within NWS AWIPS for use by
forecasters at NWS WFOs in forecasting precipitation and
severe weather
Water Vapor Winds
Image display and animation within NWS AWIPS for use by
forecasters at NWS WFOs
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AWIPS Display
Lifted Index from T/q
soundings in clear skies
Total Precipitable Water
Cloud-Top Height
Surface Skin Temperature
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AIRS granules (ascending only) for 06-10-2008
AIRS Granule
AIRS Start Time
06-10-2008 20 UTC, Temperature at 700 hPa
(K)
(K)
GOES
Sounder
+ GFS
AIRS single field-of-view retrievals
in both clear and cloudy skies
AIRS +
GFS
GFS forecast
(first guess for
GOES and
AIRS)
06-10-2008 20 UTC, Humidity [g/kg] at 700 hPa
GOES
Sounder
+ GFS
AIRS single field-of-view retrievals
in both clear and cloudy skies
AIRS +
GFS
GFS forecast
(first guess for
GOES and
AIRS)
GOES/AIRS comparison of TPW (06-10-2008, 20UTC)
GOES Sounder TPW in clear skies
AIRS TPW in clear skies
Although patterns are similar, there are still TPW differences between
GOES Sounder and AIRS due to different spectral resolutions
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GOES/AIRS comparison of LI (06-10-2008, 20UTC)
Cloudy
GOES Sounder LI in clear skies
AIRS LI in clear skies
Cloud mask differences are due to the different spatial resolutions
between AIRS (13.5 km at nadir) and GOES Sounder (10 km at nadir)
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Why GEO hyperspectral IR
sounding system ?
ƒ To support regional and convective-scale NWP over CONUS,
through unprecedented detail on 3D fields of wind,
temperature and humidity, at high vertical, horizontal and
temporal resolution.
ƒ To support nowcasting and very-short range forecasting
(VSRF). For example, to use 3D fields of wind, temperature
and humidity for monitoring moisture convergence and
convective instability, to help improve warnings of location
and intensity of convective storms.
ƒ High spatial and temporal resolution GEO soundings with
high accuracy provide important information for hurricane
track and intensity forecast. This has been demonstrated by
single field-of-view AIRS soundings.
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AIRS measurements overlay on GOES IR image (Hurricane Dean)
LEO data have
limitation on
monitoring
hurricane due to
orbital gap and
low temporal
resolution.
Why GEO? We can have data
almost anytime, anywhere !
High temporal
resolution is
unique aspect of
GEO IR
measurements
A geostationary hyperspectral sounder could provide full hourly disk coverage15
rather than the partial coverage available with polar orbiting sounders.
Retrieved 500 hPa temperature
(2008.09.06 – Used in assimilation)
(K)
(K)
CIMSS/UW
Clear sky AIRS SFOV temperature retrievals at 500 hPa on 06 September
2008, each pixel provides vertical temperature and moisture soundings.
These data are used in Hurricane Ike (2008) forecast.
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Retrieved 500 hPa temperature
(2008.09.07 - Used in assimilation)
(K)
(K)
CIMSS/UW
Clear sky AIRS SFOV temperature retrievals at 500 hPa on 07 September
2008, each pixel provides vertical temperature and moisture soundings.
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Assimilation Experiments
ƒ NCAR WRF/DART ensemble assimilation is performed at
36 km resolution during September 6-8 00UTC, 2008.
ƒ NCEP 1 degree global analysis is used as initial
condition.
ƒ CTL run: Assimilate radiosonde, satellite cloud winds,
aircraft data, ship, and land surface data.
ƒ AIRS (CIMSS) run: Same as CTL run plus CIMSS single
field-of-view AIRS T and Q soundings (13.5 km at Nadir).
ƒ Ensemble analysis is generated every 6 hours.
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Tracks of ensemble mean analysis on Hurricane IKE
CTL run: Assimilate radiosonde, satellite
cloud winds, aircraft data, and surface data.
AIRS
Hui Liu (NCAR) and Jun Li (CIMSS)
Analysis from 06 UTC 6 to 00UTC 8 September 2008
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Track errors of on Hurricane IKE
AIRS
Hui Liu (NCAR) and Jun Li (CIMSS)
Analysis from 06 UTC 6 to 00UTC 8 September 2008
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SLP Intensity on Hurricane IKE
AIRS
Hui Liu (NCAR) and Jun Li (CIMSS)
Analysis from 06 UTC 6 to 00UTC 8 September 2008
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Demonstration of GEO advanced
sounder for storm nowcasting
ƒ The IHOP (June 12, 2002) numerical model output (WRF,
2 km, 15 minutes) are used to simulate the radiances of
ABI/GOES Sounder like and GEO HES like instruments
ƒ Retrieval method is applied to convert the radiances into
temperature and moisture profiles
ƒ Derived product (e.g., Lifted Index) from true (WRF), HES
like, ABI/GOES Sounder like are demonstrated along with
the simulated Radar imagery
ƒ Moisture profiles from HES like and ABI like are compared
with true, HES like depicts detailed and accurate moisture
vertical structures.
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HES like
True
Red = extreme instability
Simulated Radar
ABI/GOES Sounder like
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True
GEO Advanced Sounder
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Summary
ƒ Current GOES Sounder provides useful information for
severe weather forecast over CONUS, comparisons between
GOES Sounder and AIRS show that both provide similar
TPW but AIRS provides much better vertical moisture
structures
ƒ High spatial and high temporal GEO advanced sounder can
provide needed instability and warning information hours
early than the current GOES Sounder
ƒ Radar shows information after storm development
ƒ GEO advanced sounder can significantly improve hurricane
track and intensity forecast
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