Transcript GSICS - Main Site

Global Space-based InterCalibration System (GSICS)
Mitchell D. Goldberg, Chief
NOAA/NESDIS
Center for SaTellite Applications and Research (STAR)
Satellite Meteorology and Climate Division
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Outline
• What is GSICS
• Why GSICS?
• How to implement GSICS
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What is GSICS?
• Global Space-based Inter-Calibration
System (GSICS)
• WMO sponsored
• Goal - Enhance calibration and validation
of satellite observations and to
intercalibrate critical components global
observing system
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Motivation
• Applications are becoming more demanding
• Demanding applications require accurate,
well calibrated & characterized
measurements
• Intercalibration of instruments achieves
comparability of measurements from different
instruments.
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Climate & Weather Requirements
• Need excellent accuracy and long-term
stability
• Instruments must be inter-calibrated
• Need high precision (low noise)
• Measurements must be well characterized
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Error Characteristics
y(t2)
• Accuracy (bias)
• Precision (standard
deviation)
p(t2)
p(t1)
• Stability
y(t1)
True y
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GSICS formulation
• 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
• CGMS tasked the WMO
Space Programme to
build an international
consensus and
consortium for a global
space-based intercalibration system for the
World Weather Watch
(WWW)/Global Observing
System (GOS).
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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).
The following experts participated:
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Mitch Goldberg – NOAA/NESDIS (Chair)
Gerald Frazer – NIST
Donald Hinsman – WMO (Space Program Director)
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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WMO has approved the development of an
Implementation Plan
• Co-ordination Group of Meteorological Satellites (CGMS)
XXXIII WMO- WP-21 presented a draft concept and
strategy for a Global Space-based Inter-calibration
System (GSICS)
• Action 33.15: CGMS Members to establish a Task Force
lead by NESDIS (Mitch Goldberg) with participation by
EUMETSAT (Johannes Schmetz), JMA (Toshiyuki
Kurino), CMA (Xu Jianmin) and assisted by the WMO
Space Programme to prepare a draft Implementation
Plan for GSICS by 1 July 2006 for review by CGMS
Members by 1 August 2006 and approval at CGMS
XXXIV.
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GSICS Objectives
• To improve the use of space-based global observations
for weather, climate and environmental applications
through operational inter-calibration of satellite sensors.
• To provide for the ability to re-calibrate archived satellite
data using the GSICS intercalibration system to enable
the creation of stable long-term climate data sets
• To ensure that instruments meet specification, prelaunch tests are traceable to SI standards, and the onorbit satellite instrument observations are well calibrated
by means of careful analysis of instrument performance,
satellite intercalibration, and validation with reference
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sites
Benefits - High Level
• Improved satellite products to observe climate
variability and trends, and to support
reanalysis projects.
• Improved utility (ease of use) of satellite
radiances in NWP
• Reduced cost-benefit ratio from an optimized
global system of satellites
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Benefits - Technical
• Consistent calibration of space-based radiometers
• Significantly improved characterization of space-based
radiometers
• Improved overall performance by moving towards
absolute calibration
• Improved understanding of physical processes in
atmospheric models
• Improved detection of climate trends, by tying entire
intercalibrated system to absolute SI standards and
ensuring that any drift of the entire intercalibrated
system truly reflects changes of the Earth System.
• Improved assessment of sensor performance to
validate that contractors meet the performance
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standards in their SOW.
Prerequisites
 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 intercalibration
 Independent observations (calibration/validation
sites – ground based, aircraft)
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Building Blocks for Satellite Intercalibration
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Collocation
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Data collection
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Archive, metadata - easily accessible
Coordinated operational data analyses
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Determination and distribution of locations for
simultaneous observations by different sensors
(space-based and in-situ)
Collocation with benchmark measurements
Processing centers for assembling collocated
data
Expert teams
Assessments
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communication including recommendations
Vicarious coefficient updates for “drifting”
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sensors
Global Space-based Inter-Calibration System
(GSICS)
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GSICS Organizational Chart
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GSICS Executive Panel
• Monitor and evaluate the evolution and operations of the GSICS.
• Provide guidance and advice on the development and enhancement
of the GSICS.
• Consist of representatives from the WMO and each satellite
agency.
• Establish the GSICS Research Working Group (GRWG) and a Data
Working Group (GDWG) to assist in the coordination, planning and
implementation of GSICS research and data management activities
• The GRWG will consist of scientists and the GDWG of data
management experts representing the participating agencies.
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The GSICS Coordination Centre (GCC)
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The GSICS Coordination Centre (GCC)
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GSICS Processing and Research Centers
(GPRC)
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Toward an Integrated System for Intersatellite Calibration of POES and GOES
using the SNO Method
POES
GOES vs. POES
SNO: Simultaneous Nadir Overpass
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GSICS Processing and Research Centers
(GPRC)
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Satellite Intercalibration improves MSU
time series
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NESDIS Operational Calibration
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NOAA10
NOAA11
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NOAA12
NOAA14
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Linear (NOAA10)
Trend:
-1
N10 = - 0.40 K Dec ,
Linear (NOAA11)
-1
N11 = 0.80 K Dec ,
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N12 =
-1
0.36 K Dec ,
N14 = 0.43 K Dec
Linear (NOAA12)
-1
Linear (NOAA14)
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1987
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1989
1991
1993
1995
1997
1999
2001
2003
Improved Calibration
NOAA10
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NOAA11
NOAA12
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NOAA14
Linear (NOAA10)
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Simultaneous Nadir Overpass (SNO)
Trend:
N10 = -0.39 K Dec -1,
N12 = 0.43 K Dec
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-1
,
N11 = 0.58 K Dec -1
N14 = 0.31 K Dec
Linear (NOAA11)
-1
Linear (NOAA12)
Linear (NOAA14)
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1987
1989
1991
1993
1995
1997
1999
2001
2003
Improved calibrated radiances using SNO- improved
differences between sensors by order of magnitude.
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Combined
Trend = 0.17 K Dec -1
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Linear (Combined)
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0.17 K Decade-1
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250
1987
Trends for nonlinear
calibration algorithm using
SNO cross calibration
1989
1991
1993
1995
1997
1999
2001
2003
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Intersatellite Calibration using Overlapping
Records
•Global ozone time series from 5
overlapping satellites
• Each satellite’s measurements have
been subtracted from ground based
Dobson instrument observations
Ozone time series courtesy of A.J. Miller
• All satellite observations are adjusted to
those of (NOAA – 9 minus Dobson) by
taking advantage of overlapping satellite
data records
• These adjustments minimize inter-satellite
instrument biases and produce a more
stable and reliable ozone time series
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Calibration Support Segments (CSS)
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Pre-launch Instrument Characterization
Earth-based Reference Sites
Extraterrestrial Calibration Sources
Model Simulations
Benchmark Measurements
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AVHRR VIS/NIR Vicarious Calibration
using the Libyan Desert Target
–NOAA 16 AVHRR Albedo
–NOAA 17 AVHRR Albedo
CH1
CH2
CH3
Courtesy of X. Wu
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AVHRR 0.86um channel
(with vicarious calibration)
N-16
coeff.
update
N-17
coeff.
update
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Understanding Global Biases and Developing
Calibration Algorithms for Bias Correction
SSMIS (54.4 GHz)
•SSMIS is the first conical microwave sounding instrument, precursor of NPOESS
CMIS.
•Shown are the differences between observed and simulated measurements.
Biases are caused by 1) antenna emission, 2) direct solar heating to warm load and
3) stray light contamination to its calibration targets.
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National Roadmap
Produce high-quality and well characterized
measurements from domestic and foreign satellites for
weather and climate applications through the state-ofthe art calibration, intercalibration and validation
procedures
National contribution to GSICS
•Prelaunch Instrument Characterization
•On-orbit Calibration, Intercalibration and Validation
•Reference Sites
•Data Management
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