Global Space-based Inter-Calibration System

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Global Space-based Inter-Calibration System

• Mitch Goldberg
• GSICS, Executive Chair
• NOAA/NESDIS
• Chief, Satellite Meteorology and Climatology
  Division
• Mitch.Goldberg_at_noaa.gov

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What is GSICS?

• Global Space-based Inter-Calibration System
  (GSICS)
• Goal - Enhance calibration and validation of
  satellite observations and to intercalibrate
  critical components global observing system
• Part of WMO Space Programme
• GSICS Implementation Plan and Program formally
  endorsed at CGMS 34 (11/06)

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GSICS Mission

• To provide sustained calibration and validation
  of satellite observations
• To intercalibrate critical components of the
  global observing system to climate quality
  benchmark observations and/or reference sites
• To provide corrected observations and/or
  correction algorithms to the user community for
  current and historical data

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Or in technical terms

• Quantify the differences magnitude and
  uncertainty
• Correct the differences physical basis and
  empirical removal
• Diagnose the differences root cause analysis

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Motivation

• Demanding applications require well calibrated
  and intercalibrated measurements
• Climate Data Records
• Radiance Assimilation in Numerical Weather
  Prediction
• Data Fusion
• Growing Global Observing System (GOS)
• Intercalibration of instruments achieves
  comparability of measurements from different
  instruments

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Space-Based component of the Global Observing
System (GOS)
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Intercalibration of instruments achieves
comparability of measurements from different
instruments
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Calibration is Critical for Climate Change
Detection
Before intercalibraion
After intercalibration
Trend of global oceanic total precipitable water
decreases from 0.54 mm/decade to 0.34 mm/decade
after intercalibrations! Calibration
uncertainties translate to uncertainties in
climate change detection
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Do we Care about Satellite Biases in NWP?After
McNally, Bell, et al. ECMWF, 2005 2009

• Yes! Because
• 1) We wish to understand the origin of the bias
  and ideally correct instrument / RT / NWP model
  at source
• 2) In principle we do not wish to apply a
  correction to unbiased satellite data if it is
  the NWP model which is biased. Doing so is likely
  to
• Re-enforce the model bias and degrade the
  analysis fit to other observations
• Produce a biased analysis (bad for re-analysis /
  climate applications)

SSMIS calibration biases cause regional weather
patterns
More accurate satellite observations will
facilitate discovery of model errors and their
correction. Additional gains in forecast accuracy
can be expected.
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Historical Background

• The GCOS Climate Monitoring Principles (GCMPs)
  were extended to address the problems associated
  with developing long-term climate data records
  from satellite observations
• Stable orbits
• Continuity and adequate overlap of satellite
  observations
• Improved calibration and validation

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Background

• In response to the request by WMO and CEOS on
  the calibration item of the GCMPs, the CGMS
  (Sochi, May 2004), the EUMETSAT SAF on Climate
  Monitoring (Hamburg, July 2004) and WMOs CBS
  (St. Petersburg, Feb. 2005) had detailed
  discussions and tasked the WMO Space Programme to
  help building an international consensus and
  consortium for a global space-based
  inter-calibration system for the World Weather
  Watch (WWW)/Global Observing System (GOS).

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GSICS Formulation

• The Space Programme of WMO initiated a
  discussion and held two meetings (June and July
  2005) to develop the concept of a Global
  Space-based Inter-Calibration System (GSICS).
• GSICS Implementation Plan and Program formally
  endorsed at CGMS 34 (11/06)

• Formulation team
• Mitch Goldberg NOAA/NESDIS (Chair)
• Gerald Fraser /Raju Datla NIST
• Donald Hinsman WMO
• Jerome Lafeullie, WMO
• Xu Jianmin (CMA)
• Toshiyuki Kurino (JMA)
• John LeMarshall - JC Sat. Data Assimilation
• Paul Menzel NOAA/NESDIS
• Tillmann Mohr WMO
• Hank Revercomb Univ. of Wisconsin
• Johannes Schmetz Eumetsat
• Jörg Schulz DWD, CM SAF
• William Smith Hampton University
• Steve Ungar CEOS, Chairman WG Cal/Val

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Building Blocks for Satellite Intercalibration

• Collocation
• Determination and distribution of locations for
  simultaneous observations by different sensors
  (space-based and in-situ)
• Collocation with benchmark measurements
• Data collection
• Archive, metadata - easily accessible
• Coordinated operational data analyses
• Processing centers for assembling collocated data
• Expert teams
• Assessments
• communication including recommendations
• Vicarious coefficient updates for drifting
  sensors

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Other key building blocks for accurate
measurements and intercalibration

• Extensive pre-launch characterization of all
  instruments traceable to SI standards
• Benchmark instruments in space with appropriate
  accuracy, spectral coverage and resolution to act
  as a standard for inter-calibration
• Independent observations (calibration/validation
  sites ground based, aircraft)

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GSICS Organization
Research working group - Consensus algorithms
Data working group - Formats, Servers
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Organizations contributing to GSICS

• NOAA
• NIST
• NASA
• EUMETSAT
• CNES
• CMA
• JMA
• KMA
• WMO

• Official observers
• JAXA
• ESA

GSICS current focus is on the intercalibration of
operational satellites, and makes use of key
research instruments such as AIRS and MODIS
to intercalibration the operational instruments
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Current focus of GSICS

• Interagency collaboration on algorithms (GRWG)
  and data (GDWG)
• Product acceptance and documentation
  requirements, metadata standards, data
  formats, website standards
• Routine intercalibration (monitor and correct) of
  all operational GEO Infrared imagers using IASI
  and AIRS
• MODIS and Deep Convective Clouds for visible
  channels
• Intercalibration of LEO instruments
• HIRS, SSMI, AMSU, MHS, AVHRR, AIRS, IASI, FY3,
• GOME-2, OMI, SBUV
• Traceability
• Campaigns
• Key collocation datasets
• Requirements for pre-launch calibration
• Root causes and corrections

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Best Practice Guidelines for Pre-Launch
Characterization and Calibration of Instruments
for Optical Remote Sensing
GSICS first guideline document
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Simultaneous Nadir Overpass (SNO) Method-a core
component of GSICS
POES intercalibration

• Useful for remote sensing scientists,
  climatologists, as well as calibration and
  instrument scientists
• Support new initiatives (GEOSS and GSICS)
• Significant progress are expected in GOES/POES
  intercal in the near future

• Has been applied to microwave, vis/nir, and
  infrared radiometers for on-orbit performance
  trending and climate calibration support
• Capabilities of 0.1 K for sounders and 1 for
  vis/nir have been demonstrated in pilot studies
• Method has been adopted by other agencies

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GOES vs. POES
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Integrated Cal/Val System Architecture
Calibration Opportunity Prediction
Data Acquisition Scheduler
Calibration Opportunity Register (COR)
Raw Data Acquisition for Calibration Analyses
Store Raw Data for Calibration Analysis
SNO/ SCO Rad. Bias and Spectral Analysis
Earth Lunar Calibration
Calibration Parameter Noise/ Stability Monitoring
RTM Model Rad. at Calibration Reference Sites
Inter-sensor Bias and Spectral Analysis
Geolocation Assessment (Coastlines, etc.)
Assessment Reports and GSICS Corrections
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First agency-wide coordinated GSICS project is
the intercalibration of geostationary infrared
channels with IASI and AIRS
Web Accessible
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Web-based Monitoring MTSAT-AIRS/IASI

• Monitoring Example
• from JMA website
• MTSAT-1R AIRS/IASI
• Time Series of Bias
• at 220, 250, 290K
• and lots more

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Monitoring GOES12-AIRS at NOAA
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Monitoring Meteosat9-IASI
IR3.9-IR12.0 Small, stable Biases lt0.2K 0.05K
IR13.4 Larger Bias -1K-0.05K/mnthJump
Time series of brightness temperature differences
between MSG2-IASI for typical clear-sky
radiances. Error bars represent statistical
uncertainty on each mean bias (may be very
small).
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GSICS Correction Algorithm for Geostationary
Infrared Imagers
The first major deliverable to the user community
is the GSICS correction algorithm for
geostationary satellites. The user applies
the correction to the original data using GSICS
provided software and coefficients. The
correction adjusts the GOES data to be consistent
with IASI and AIRS. The figures to the left show
the difference between observed and calculated
brightness temperatures (from NCEP analysis)
correction, respectively. The bias is reduced
from 3 K to nearly zero.
Before 3K Bias
After 0K Bias
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GSICS Correction available for MSG

• EUMETSAT routinely run prototype
  inter-calibration of MSG-IASI
• Results published on webpage for
  Inter-calibration Services
• http//www.eumetsat.int/Home/Main/Access_to_Data/I
  ntercalibrationServices
• This webpage also allows access to coefficients
  required to apply GSICS Correction
• Users can implement this as change in calibration
  coefficients

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Promoting access to instrument performance
monitoring is also part of GSICS

• GSICS beginning to develop observing system
  monitoring tools for all GSICS partners. Above
  is example of NOAA tool for NOAA-19 OV and
  long-term monitoring
• The system has detected instrument anomalies,
  provided an important tool for diagnoses, data
  quality assurance, and for short and long term
  applications

Courtesy of F.Weng
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CNES SADE Data Base is critical for assessing
stability of visible/near infrared reference
instruments for intercalibration
Time series of the ratio of the ESA MERIS to
NASA MODIS 0.665 micron visible channel
reflectance from observations at 19 desert sites
in North Africa and Saudi Arabia. The results
show very good agreement and stability between
the two sensors

• 19 sites selected over North Africa and Arabia

GSICS Feb 2008 Claire Tinel / CNES
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Now with a foundation, we are engaging the User
Community

• Satellite Community generation of CDRs
• New WMO Space Programme SCOPE-CM
• GRP (ISCCP)
• National programs - SDS, SAFs,
• Satellite Community - NWP direct radiance
  assimilation
• Reanalysis Community
• Next reanalysis 2012 - 2015
• GSICS major deliverable - intercalibrated
  geostationary data using IASI/AIRS from 2003
  2010
• Satellite Acquisition Programs
• Prelaunch instrument characterization guidelines
• Cal/Val Plans

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First GSICS User Workshop

• Sept. 22, 2009 at EUMETSAT Satellite Conference
  in Bath, UK
• Users included ECMWF, UKMO, JCSDA, CM-SAF, DWD,
  RMIB, KNMI, Hadley Centre, ISCCP
• Over 60 participants
• Very positive feedback, established beta users
  with ISCCP, CM-SAF, and NWP/Reanalysis groups
  (Met Office, ECMWF, JCSDA)

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SCOPE-CM to maximize data usage
Sustained and Coordinated Processing of
Environmental Satellite Data

• Regional/Specialized Satellite Centres
• Address the requirements of GCOS in a
  cost-effective, coordinated manner, capitalising
  upon the existing expertise and infrastructures.
• Continuous and sustained provision of
  high-quality ECVs
• GSICS enables the generation of Fundamental
  Climate Data records and provides the basis for
  sustained climate monitoring and the generation
  of ECV satellite products.

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Summary

• Coordinated international calibration program for
  sustained intercalibration by instrument
  operators
• Best practices/requirements for monitoring
  observing system performance (with CEOS WGCV)
• Best practices/requirements for prelaunch
  characterisation (with CEOS WGCV)
• Establish requirements for cal/val (with CEOS
  WGCV)
• Advocate for benchmark systems
• Quarterly reports of observing system performance
  and recommended solutions
• Improved sensor characterisation
• High quality traceable intercaibrated radiances
  for NWP, Climate and all satellite applications

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