CalVal and Continuity of Environmental Observations

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Cal/Val and Continuity of Environmental
Observations
Jack KayeErnest Hilsenrath NASA
HeadquartersASIC3 WorkshopMay 16,
2006Landsdowne, VA
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Outline

• Environmental observations
• A historical perspective
• Developing climate data sets
• Atmospheric composition, a success
• under way
• Role of cal/val
• Expectations for the future

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Beginnings of Earth Science
Nimbus-7
V-2 Rocket

• 1960s to 1980s Exploring the Possibilities
• Birth and early development of satellite remote
  sensing
• Technology demonstration was the driver

Apollo
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NASA Earth Science

• 1990 to 2000 Surveying the Earth System from
  Space
• Evolution of the Earth System Science concept
• Focus on providing a broad range of measurements
  to observe, document, and understand Earth system
  change
• 2000 to 2020 Focus on Societal Needs
• Answer high-priority science questions with
  relevance to national/international economic and
  policy
• End-to-end science, technology applications
  approach
• 2020 and Beyond Broad Use of the View From
  Space
• Providing information from space to
  decision-makers in a timely and affordable manner
• Global on-line data distribution and application

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Serving Societal Needs Requires Scientific
Understanding

• How is the Earth changing and what are the
  consequences for life on Earth?
• How is the global Earth system changing?
• What are the primary causes of change in the
  Earth system?
• How does the Earth system respond to natural and
  human-induced changes?
• What are the consequences of changes in the Earth
  system for human civilization?
• How well can we predict future changes to the
  Earth system?

The answer to these questions rely on Cal/Val
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Tools - 16 Satellites in Orbit with More to Come
TRMM
GRACE
Cloudsat
CALIPSO
NOAA POES
Aqua
TOPEX
TOMS Earth Probe
Terra
EO-1
SeaWiFS
Aura
Landsat
Jason
SORCE
ICESat
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Is the Earth Changing?

• How are global ecosystems changing?
• What are the causes?
• Marine productivity has been measured
• by multiple satellites
• 6 global decrease (2.8 Pg C/yr) in
• based on CZCS (1978 -1986) SeaWiFS
• (1997 - 2003) climatologies.
• 70 of change at high latitudes.
• Productivity tended to increase at low
• latitudes
• Cal/Val is essential connect data sets

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• For 1980 to 2000
• Statistically significant trends observed
• 17 per decade over China
• 10 per decade over India
• 20 drop per decade over Europe
• Consistent with sulfur emissions
• Aura OMI will continue the record.
• Cross calibration essential

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Stratospheric Ozone Monitoring
Clean Air Act mandates that NASA conducts
research and take observations in the stratosphere

• Stratospheric ozone has been
• observed by satellites since 1970
• Global ozone loss is about 5
• Antarctic Spring loss has been
• dramatic. Similar losses have
• appeared in the Arctic
• International treaties banning
• CFCs seems to have slowed down
• loss rate based on careful
• calibration of TOMS and now Aura/OMI data
• Climate change could effect recovery of ozone

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Stratospheric H2O

• Water vapor is chemically and radiatively active
• Tropopause temperatures have been decreasing.
• Balloon observations found H2O decrease
  consistent with tropopause temperature.
• UARS found no H2O decrease (1990-2000), but
  abrupt drop afterwards
• Aura will monitor H2O and temperatures Cross
  calibration needed

17 km global mean HALOE H2O from HALOE,
1991-2005(Randel et al. 2004 updated to the
present)
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Mission Cal/Val Paradigm

• Post launch and Data Analysis
• On-board calibration
• - Solar, lunar, vicarious
• Radiative transfer calculations
• - Comparisons
• - Atmospheric correction
• Algorithm testing and refinement
• Validation campaigns
• - QC and archival
• Mission product comparisons
• Provisional release (validation)

• Instrument and Prelaunch
• Satellite sensor analyses
• - Design evaluation
• - Prelaunch characterization
• Linearity, polarization,
• radiometric response, etc.
• Round robins
• - Calibration
• - Data Analysis
• Field measurement
• - instrument development
• - protocols and calibration

Cal/Val is an iterative process
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Prelaunch Calibration

• The EOS program has made major investments
• for pre-launch sensor calibrations
• Sensors operate from UV to millimeter wave
• EOS Project Scientist for calibration
• Supported in-house, NIST, and universities for
• calibration services and advice
• Organized intercomparisons of instruments
  sources
• and detector standards (round robins)
• Instrument and subsystem calibrations
• Spectral irradiance and radiance
• BRDF calibrations
• Detector characterization
• Instrument slit functions
• Straylight spectral and spatial

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HIRDLS Calibration

• UK (Oxford U.) partner makes major contribution
  to calibration
• Vigorous calibration because of 1 km vertical
  resolution and high absolute accuracy
• Space simulations
• Radiometric gain
• Spectral bandpass
• FOV (2 arc seconds)

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Post Launch Validation

• NASA employs multiple assets for validation
• A major component of mission with allocated
  resources for conducting and analyzing validation
  data
• Collaboration with National and International
  partners is essential for success

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MODIS/Aqua SeaWiFS Chlorophyll
ValidationSatellite vs. In Situ Observations
In Situ Statistics Observations 1293
Range 0.024-30.2 mg/m3 Median ratio 0.998
(satellite/in situ) Median abs. diff 26
In Situ Statistics Observations 263
Range 0.03-38 mg/m3 Median ratio 1.08
(satellite/in situ) Median abs. diff 40.4
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A-Train Validation and Science

• Unique Opportunity for validation
• and synergistic science
• Climate change
• OMI , MODIS, Parasol, CALIPSO Aerosols
  characteristics
• MLS, AIRS and Cloudsat Water vapor and clouds
• OMI and MODIS Clouds heights
• HIRDLS, AIRS and CALIPSO Cirrus clouds
• Ozone Trends
• OMI and AIRS Column ozone
• Air Quality
• TES and AIRS CO (also MOPITT)
• OMI and MODIS Smoke and Dust
• Calibrations across ES missions is essential for
  continuity
• Pre-launch calibration

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ICESat Validation

• ICESat accurately tracks ice surface height
• Cal/val methods include
• Detection of surface illumination and comparison
  with in-situ measurements
• Comparison with in situ measurements independent
  of data product
• Comparison of profiles with independently derived
  topographic surfaces from aircraft lidar
• Special maneuvers over the Pacific Ocean to
  determine laser pointing biases and their
  temporal variation

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Radar Altimetry Validation

• Validation using tide gauge measurements located
  throughout Pacific ocean
• Comparisons among Envisat, ERS-2, CALIPSO and
  ICESat?

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Scatterometer Vector Wind Validation
Wentz et al., 2005
Wentz Smith, 1999

• Open-Ocean Buoys
• Collocated surface wind speed/direction msmt
• Auxiliary buoy data used to transform
• anemometer data to 10 m neutral wind
• measured by scatterometer

• Statistical Comparison with
• NWP Surface Wind Analyses
• Highlights model function/
• retrieval errors, viewing
• geometry dependences

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TC4 Campaign

• Major A/C campaign for Cloudsat, CALIPSO, Aura
  validation
• Tropical Tropopause Layer
• Observations of cirrus anvils
• Water/chemicals across the tropopause
• Characterize heating rates
• NASA A/C platfoms DC-8, ER-2, WB-57

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NPP and NPOESS

• Joint effort between NOAA, NASA, and DoD to merge
  civilian and defense meteorological satellites
  Managed by the IPO
• Meet operational needs for NOAA
• Continuation of climate data records for NASA EO
  program
• Cal/Val effort is joint between contributing
  agencies and industrial partners (SSPR)
• Apply heritage capabilities from NASA EOS and
  NOAA POES
• Share responsibility
• NIST advice and services
• Instrument pre and post launch SSPR
• Vicarious a/c and ground validation -
  Government
• IPO developed on-line tools for tracking tasks
• Collaboration with Eumetsat

Satellite Instrument Calibration for Measuring
Global Climate Change, Edited by G. Ohring et
al., NISTIR 7047.
http//physics.nist.gov/Divisions/Div844/publicati
ons/NISTIR7047/nistir7047.pdf
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Summary

• Remote sensing of the environment has become
• of mature tool for observing habitability of
  the
• planet
• NASA has invested substantial resources from
• research missions towards cal/val
• Cal/val is essential for assessing the present
• and predicting the future
• Continued Cal/Val investments are necessary to
  insure
• compatibility of upcoming operational data
  sets and detecting
• long term environmental changes