NOAA18 Instrument Calibration and Validation Briefing

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NOAA-18 Instrument Calibration and Validation
Briefing

• NOAA/NESDIS/Office of Research and Applications
• As of Week of June 13-17, 2005
• For archived activities and latest news, please
  visit
• http//www.orbit.nesdis.noaa.gov/smcd/spb/n18calva
  l

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Weekly Highlights (June 13 - 17)

• AVHRR
• AVHRR on-orbit verification of calibration
  results (Sullivan)
• A few minor revisions in geolocation pixel
  offsets (Sullivan)
• Vicarious calibration results (Wu and Sullivan)
• HIRS
• Correct HIRS geolocation confirmed by Chalfant
• HIRS noise analysis and a few telecon with NASA,
  OSD and ITT (Cao, Reale )
• A website developed for displaying HIRS
  calibration trending (Cao)
• Intercomparison with NOAA-16 (Reale)
• AMSU-A
• Characterization of instrument asymmetry and
  angular dependent biases (Weng)
• On orbit AMSU NEDT table (Tsan)
• Geolocation error (Weng)
• MHS
• On orbit MHS NEDT table (Tsan)
• MHS and AMSU-B inter-comparison (Reale and
  Ferraro)
• SBUV/2
• No report

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NOAA-18 Instrument Payload
We focus on these instruments

• AVHRR/4 Advanced Very High Resolution Radiometer
• HIRS/4 High Resolution Infrared Sounder
• AMSU-A Advanced Microwave Sounding Unit-A
• MHS Microwave Humidity Sounder
• SBUV/2 Solar Backscattered Ultraviolet Radiometer

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Calibration and Validation Legend

• PRT Platinum Resistance Thermometers
• NEDN/T Noise Equivalent Delta Radiance/Temperatur
  e
• ATOVS Advanced TIROS Operational Vertical
  Sounder (TOVS)
• TOAST Total Ozone Analysis using SBUV/2 and TOVS
• MSPPS Microwave Surface and Precipitation
  Product System
• NDVI Normalized Difference Vegetation Index
• SST Sea Surface Temperature
• UV Ultraviolet
• TPW Total Precipitable Water
• CLW Cloud Liquid Water

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ORA NOAA-18 Instrument Cal/Val Mission Goals

• Monitor and improve NOAA-18 instrument
  post-launch calibration
• Assess and quantify instrument noises though
  analyzing calibration target counts and channel
  measurements
• Monitor possible instrument anomaly and provide
  recommended solution
• Quantify satellite navigation and geolocation
  errors
• Characterize other biases in radiance and
  products such as cross-track asymmetry through
  forward modeling and inter-satellite calibration
• Validate NESDIS NOAA-18 products (ATOVS and
  MSPPS, TOAST, UV index, NDVI, SST) for
  operational implementation
• Provide early demonstration and assessments of
  NOAA-18 data for improving numerical weather
  prediction through JCSDA

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Our Team

• Mitch Goldberg ORA/SMCD Division Chief, -
  Management and Technical Oversight
• Fuzhong Weng ORA/SMCD/Sensor Physics Branch
  Chief and NOAA-18 cal/val team leader, instrument
  asymmetry and microwave products and algorithms,
  radiance bias assessments for NWP model
  applications
• Changyong Cao HIRS instrument calibration
• Fred Wu AVHRR VIS/IR instrument calibration
• Tsan Mo AMSU/MHS instrument calibration
• Jerry Sullivan AVHRR thermal channel
  calibration/ NDVI validation
• Tony Reale HIRS/AMSU/MHS sounding
  channel/products validation
• Mike Chalfant HIRS/AMSU/MHS sounding
  channel/products validation /geolocation
• Ralph Ferraro AMSU/MHS window channels/MSPPS
  products validation
• Larry Flynn SBUV product validation
• Tom Kleespies AMSU on-orbit verification
• Hank Drahos Sounding product validation
• Dan Tarpley AVHRR product NDVI monitoring
• John LeMashall Impacts assessments of NOAA-18
  data for NWP applications

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HIRS Cal/Val News

• A telecon was held by NASA for the HIRS/NOAA-18
  investigation. Evidence suggests that the noise
  in HIRS/NOAA-18 longwave channels are decreasing
  slowly after the initial drop last Friday.
• A calibration trending website showing NEDN to
  assist in the diagnosis of the HIRS NEDN problem
• http//www.orbit.nesdis.noaa.gov/smcd/spb/multis
  ensor/hirs/nedn
• Developed experimental web based trending system
  in 2 days led by Dr. Changyong Cao
• Longterm trend of all calibration cycles clearly
  shows that ch1 spaceview drifted out of range a
  large upspike in count std before the noise drop
• Web based trending time series is extremely
  useful for instrument diagnosis
• More intercomparison results with NOAA-16 HIRS

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HIRS/4 On-Orbit NEDN (6/14/2005)
On-orbit NEDN needs to be fully assessed and is
needed for NCEP data assimilation system and
physical sounding retrieval system Red channel
noise can not be assessed Yellow Noise level
is assessed but out of spec.
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N18 (left) vs N16 (right) for calibrated HIRS
radiance temperature for channel 6 (upper) and 9
(lower) June 6-7, 18Z to 6Z. The color scales
per channel, respectively are identical allowing
direct color comparison. N18 channels are more
noisy but less than for lower frequency channels
1 thru 5.
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AVHRR Cal/Val News

• AVHRR on-orbit verification of calibration target
  counts
• Space and blackbody counts are stable
• 4 PRT temperatures approach the same values,
  implying blackbody is in the equilibrium state as
  satellite moves into the dark part
• AVHRR calibration algorithms work well
• The blackbody temperature changes are monitored
  and shows in a small range of variability (only
  2K)
• Thermal channel (3-5) calibration is healthy
• Wus Vis/IR calibration algorithms are working
  well
• AVHRR NDVI products from NOAA-18 are of the
  similar quality to NOAA-16s due to robust
  visible channel calibration
• AVHRR geolocation error
• 3 pixels (N-S) and 2 pixels (E-W) offsets are
  identified using the NDVI vegetation index as a
  land-sea tag

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AVHHR Space and Blackbody Count
SPACE The Space Count is
electronically clamped and should remain constant
over many orbits. BLACKBODY The blackbody
temperature changes during an orbit, so the
Blackbody Count also changes. However, for
almost all 1-minute intervals, the temperature
only varies by about 0.02K. An average blackbody
count for 1 minute is computed, then the RMS
(root-mean-square) around this average. The
1-minute RMS is plotted for many orbits this is
a measure of AVHRR stability when viewing a
constant-temperature blackbody.
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AVHRR Blackbody Temperature Monitoring
When the NOAA-18 satellite moves into the dark
(black portion of Solar Zenith Angle curve) the
temperatures measured by the 4 PRTs approach each
other, indicating a more uniform temperature
across the blackbody. This is an important part
of C. Caos assertion that the dark part of the
orbit is the most accurate place to estimate the
true AVHRR gain, a strategy well use to
preprocess the 25-year AVHRR data set.
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AMSU Cal/Val News

• It appears that AMSU-A2 has a geolocation error
  with one pixel offset in both E-W and N-S
  directions
• AMSU-A2 and A1 window channel channels scan
  dependent biases are derived by differentiating
  radiative transfer simulations and measurements.
  Our preliminary results show AMSU-A2 module show
  less asymmetry than the previous AMSU-A2.
  However, AMSU-A1 module channel3 display larger
  asymmetry. The characterization of these
  asymmetry is needed for microwave products and
  improving NWP data assimilation quality control
  of using AMSU data
• AMSU-A NEDT on orbit is calculated and shows
  nearly all channel meet specification
• AMSU post-launch calibration parameter
  information data base (CPIDS) were successfully
  updated for larger cold space calibration counts
• AMSU-A2 cold space calibration count errors
  tolerance is increased from 25 counts to 50
  counts
• Overall AMSU calibration algorithms are healthy
  with reasonable gains, and variability in cold
  and warm calibration targets

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AMSU-A On-Orbit NEDT
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NOAA-18 AMSU Asymmetry Characterization
Vertical coordinate shows the mean differences
between simulations and observations. Horizontal
coordinate is the local zenith angle which
corresponds to beam position from 1 to 30.
AMSU-A2 module includes two frequencies of 23.8
and 31.4 GHz, A1 module include 50.3 and 89 GHz.
It appears A2 module does not show any asymmetric
features as previous AMSU-A2 which is very
positive news. The results are preliminary and
are based on 6 days of average.
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NOAA-18 AMSU Geolocation Offset
AMSU-A channel 1 image over the west coast of
California. The striking contrast between land
and ocean from microwave window channel is
normally used for a sanity check for geolocation.
It appears that there is one pixel offset in AMSU
earth location in both E-S and N-S directions.
This offset is being under investigation
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MHS Cal/Val News

• MHS was verified as being properly geolocated
• he NOAA-18 MHS NEDT for each channel was
  calculated and is better than AMSU-B
• MHS looks overall nominal except for a possible
  slight warm bias for the 183 /- 1 and /- 3 GHz
  channels.
• MHS produces robust rainfall products and detect
  more light precipitation

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MHS On-Orbit NEDT
MHS
AMSU-B
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(No Transcript)
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SBUV/2 Status

• SBUV/2 is making some measurements in its
  standard operating mode
• Ozone retrieval is performed. The change in total
  ozone behavior yesterday is probably related to a
  test switching from anode to cathode mode for the
  PMT

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Overall Summary

• Most instruments are meeting specification with
  the current exception of HIRS
• AMSU-A NEDT meets specification
• AVHRR NOAA-18 NDVI product appear to be
  consistent with NOAA-16
• MHS noise is lower than AMSU-B
• All instruments except AVHHR/3) have been
  verified as being properly geolocated

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Next Step

• Continue monitoring HIRS/4 noises with the
  trending website and trending website updated for
  other sensors
• Inter-satellite calibration using simultaneous
  nadir overpassing (SNO) method
• Assess the readiness of AMSU and MHS with global
  forward model simulations for NWP applications