Global Space-based Inter-Calibration System

Mitch GoldbergGSICS, Executive Chair

NOAA/NESDISChief, Satellite Meteorology and Climatology Division

Mitch.Goldberg@noaa.gov

1The 23rd CEOS Plenary I Phuket, Thailand I 3-5 November 2009

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

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)

Intercalibration of instruments achieves comparability of measurements from different instruments

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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

Calibration is Critical for 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)

More accurate satellite observations will facilitate discovery of model errors and their correction. Additional gains in forecast accuracy can be expected.

SSMIS calibration biases cause regional weather patterns

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

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 WMO’s 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).

Background

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, WMOXu 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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CSS GPRCGPRCCSS

GSICSExecutive Panel

GRWG GDWG

GPRCGCCCSS

Calibration Support Segments (reference sites, benchmark measurements, aircraft, model simulations)

Coordination Center Regional Processing ResearchCenters at Satellite Agencies

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

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

GOES vs. POES

POES intercalibration

•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

• 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

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Calibration Opportunity Prediction

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

Calibration Opportunity Register(COR)

Integrated Cal/Val System Architecture

Data Acquisition Scheduler

Raw Data Acquisition for Calibration Analyses

Store Raw Data for Calibration Analysis

2020

Ch6Ch4 Ch3

Ch2

IASI

AIRS

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

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).

IR3.9-IR12.0: Small, stable Biases <0.2K ± 0.05K

IR13.4: Larger Bias ~-1K

-0.05K/mnth+Jump

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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/IntercalibrationServices

• This webpage also allows access to coefficients required to apply GSICS Correction

• Users can implement this as change in calibration coefficients

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

GSICS – Feb 2008 – Claire Tinel / CNES 27

• 19 sites selected over North Africa and Arabia

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

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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Users

Satellites & sensors

Satellite data

Essential Climate products

GOS GSICS

ConsistentCalibrateddata sets

SCOPE-CM

• 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.

SCOPE-CM to maximize data usage

Sustained and Coordinated Processing of Environmental Satellite Data

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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