Update on GSICS Inter Calibration Product Development

Transcription

1 Special Issue of the IEEE TGRS on Inter-Calibration of Satellite Instruments : Update on GSICS Inter Calibration Product Development Tim Hewison (EUMETSAT) [GSICS Research Working Group Chair] Dave Doelling (NASA) [VIS/NIR Sub Group Chair], Ralph Ferraro (NOAA) [Microwave Sub Group Chair], Rose Munro (EUMETSAT) [UV Sub Group Chair] + Many other members of GSICS Research Working Group

2 Overview Introduction to GSICS GEO LEO IR: Hyperspectral SNO GEO LEO VIS: Deep Convective Clouds VIS/NIR: Moon Microwave Sub Group UV Sub Group Prime GSICS Corrections Slide: 2

3 GlobalSpace based based Inter Calibration System What is GSICS? Global Space based Inter Calibration System Initiative of CGMS and WMO Effort to produce consistent, well calibrated data from the internationalconstellation of Earth Observing satellites What are the basic strategies of GSICS? Improve on orbit calibration by developing an integrated inter comparison system Initially for GEO LEO Inter satellite calibration Being extended to LEO LEO Using externalreferencesreferences as necessary Best practices for calibration & characterisation This will allow us to: Improve consistencybetween instruments Reduce bias in Level 1 and 2 products Provide traceability of measurements Retrospectively re calibrate archive data Better specify future instruments EUMETSAT CNES JMA NOAA CMA KMA ISRO NASA WMO USGS NIST JAXA Slide: 3 ROSHYDROMET IMD ESA

4 GSICS Principles Systematic generation of inter calibration products for Level 1 data from satellite sensors to compare, monitor and correct the calibration of monitored instruments to community references by generating calibration corrections on a routine operational basis with specified uncertainties through well documented, peer reviewed procedures based on various techniques to ensure consistent and robust results Delivery to users Free and open access Adopting community standards To promote Greater understanding of instruments absolutecalibration, by analysing the root causes of biases More accurate and more globally consistent retrieved L2 products Inter operability for more accurate environmental, climate and weather forecasting products TRACEABILITY / UNBROKEN CHAINS OF COMPARISONS Slide: 4

5 GSICS Bias Monitoring GSICS ProductTypes Routine comparisons of satellite radiances against reference GSICS Correction Function to correct issued radiances for consistent calibration with reference GSICS Calibration Alternative Calibration Coefficients = operational calibration + inter calibration corrections GSICS Reports & Guidelines Recommendations to modify processing/practices Design and Operation of future satelliteinstrumentsinstruments For Operational Environmental Satellites Infra red recalibration (GEO and LEO) Pre Operational & Demo status (current operational satellites) Near real time and re analysis Visible and near infrared recalibration (GEO and LEO) In development within GSICS Microwave Conical & Cross track Scanners (LEO) In development with GPM XCAL Historic Instruments In development for SCOPE CM Slide: 5

6 GEO LEO IR Hyperspectral SNO Simultaneous near Nadir Overpasses of GEO imager and LEO sounder Select Collocations Schematic illustration of the geostationary orbit (GEO) and polar low Earth orbit (LEO) satellites and distribution of their collocated observations. Slide: 6

7 GEO LEO IR Hyperspectral SNO Simultaneous near Nadir Overpasses of GEO imager and LEO sounder Select Collocations Spatial, temporal and geometric thresholds Spectral Convolution: Convolve o LEO Radiance a Spectra with GEO Spectral Response Functions to synthesise radiance in GEO channels Example radiance spectra measured by IASI (black), convolved with the Spectral Response Functions of SEVIRI channels 3-11 from right to left (colored shaded areas). Slide: 7

8 GEO LEO IR Hyperspectral SNO Simultaneous near Nadir Overpasses of GEO imager and LEO sounder Select Collocations LEO FoV~10km Spatial, temporal and geometric thresholds Spectral Convolution: Convolve o LEO Radiance a Spectra with GEO Spectral Response Functions to synthesise radiance in GEO channels Spatial Averaging Average GEO pixels in each LEO FoV Standard Deviation of GEO pixels as weight ~ 3x3 GEO pixels Illustration of spatial transformation. Small circles represent the GEO FoVs and the two large circles represent the LEO FoV for the extreme cases of FY2-IASI, where nxm=3x3 and SEVIRI-IASI, where nxm=5x5. Slide: 8

9 GEO LEO IR Hyperspectral SNO Simultaneous near Nadir Overpasses of GEO imager and LEO sounder Select Collocations Spatial, temporal and geometric thresholds Spectral Convolution: Convolve o LEO Radiance a Spectra with GEO Spectral Response Functions to synthesise radiance in GEO channels Spatial Averaging Average GEO pixels in each LEO FoV Standard Deviation of GEO pixels as weight WihtdR Weighted Regression of LEO v GEO rads Evaluate Bias for Standard Radiance Scene Weighted linear regression of L GEO REF and <L GEO > for Meteosat μm channel based on single overpass of IASI Slide: 9

10 GEO LEO IR Hyperspectral SNO Simultaneous near Nadir Overpasses of GEO imager and LEO sounder Select Collocations Spatial, temporal and geometric thresholds Spectral Convolution: Convolve o LEO Radiance a Spectra with GEO Spectral Response Functions to synthesise radiance in GEO channels Spatial Averaging Average GEO pixels in each LEO FoV Standard Deviation of GEO pixels as weight WihtdR Weighted Regression of LEO v GEO rads Evaluate Bias for Standard Radiance Scene Plot time series of Bias Time Series of Bias from inter-calibration of 13.4 m channel of Meteosat-10/SEVIRI with Metop-A/IASI expressed in Brightness Temperature Bias for Standard Scene Radiance Blue x = Daily Result, Blue Line=trend end Red dot = Monthly Average Slide: 10

11 GEO LEO IR Product Status GPRC Monitored Instrument Reference Instrument GSICS NRT Correction Re Analysis Correction GSICS Bias Monitoring EUMETSAT JMA NOAA Meteosat 8 10 } Meteosat 7 Metop A/IASI Pre operational Pre operational Prototype MTSAT 1R } MTSAT 2 } GOES 13 & 15 Imager GOES 11 & 12 Imager IASI (+ AIRS) Demonstration Demonstration Prototype IASI (+ AIRS) Pre operational Pre operational Demonstration Prototype GOES Sounder IASI (+ AIRS) In development In development In development CMA FY2C E IASI (+ AIRS) In development In development Prototype KMA COMS 1 IASI (+ AIRS) In development In development In development ISRO Kalpana 1/VHRR INSAT3D/VHRR IASI (+ AIRS) In development In development In development Full GSICS Product Catalog available at Slide: 11

12 Where to get the data? GSICS Bias Monitoring (prototype) Hosted on websites of GSICS Processing & Research Centres (GPRCs) GSICS Corrections GSICS Data & Products Servers THREDDS based system NetCDF format WMO GTS standard file names Unidata & CF conventions See gsics.wmo.int for links GTS = Global Telecommunication System CF = Climate and Forecast Slide: 12

13 GEO LEO VIS Deep Convective Clouds (DCCs) Bright, natural solar diffusers Near Top Of Atmosphere Little water vapour, aerosol Globally available In Equatorial Band Select coldest, brightest pixels Identify using T IR threshold Homogeneity Tests Limit viewing and solar geometry & Normalise Build up monthly PDF statistics Compare mode/mean with model/obs Derive Calibration lb Coefficients Seasonal and Land/Sea Variations Use as Pseudo Invariant Targets to transfer calibration MODIS >GEO Slide: 13 MTSAT-2 DCC detection T μm Gains for Meteosat 7/VIS TB using [K] Aqua/MODIS Reference via DCCs

14 GEO LEO VIS/NIR The Moon Dark, natural solar diffuser No kind of atmosphere Extremely stable Can apply retrospectively to generate FCDRs Globally available Select pixels of Moon Applying threshold to IR image Calculate integrated irradiance Compare with model ROLO developed by USGS <1% relative uncertainty Applicable to full Reflected Solar Band Use as Pseudo Invariant Targets to transfer calibration MODIS >GEO Lunar Calibration Workshop at EUMETSAT, 1 4 December 2014 Slide: 14 SEVIRI L1.0 image Meteosat-9/VIS06 Bias Change wrt ROLO Model Lunar Irradiance (after phase angle correction)

15 Microwave Sub Group Developments New Chair: Ralph Ferraro (NOAA) Moving ahead with ihgsics MW Scope: products/new opportunities: Imagers + sounders passive only, initially Understanding users requirements for microwave inter calibration products Identifying existing products that could meet those Encouraging their creators to submit them to the GSICS Procedure for Product Acceptance (GPPA) Reviewing them 1st candidate product is under review: Cheng Zhi Zou s MSU AMSU recalibration. GSICS Products could be developed within the Microwave Sub Group. Coordination with other groups (such as the CEOS Microwave Sub Group) would also be required to generate standards and best practices for microwave radiometer calibration. Continue to move forward on the NOAA MSU/AMSU product/methodology once the GDWG clearly defines generic standards for MW products Move forward with the EUMETSAT SSM/I (MW Imager) product/methodology Develop splinter group on bringing in SMMR data to MW imager time series Tying together other groups JAXA s participation with MW/imagers (e.g., AMSR E and AMSR 2) Engaging more closely GPM X Cal Linkages to CEOS MW subgroup future meeting in China? Slide: 15

16 UV Sub Group Developments New Chair: Rose Munro (EUMETSAT) Moving ahead with ihgsics UV Vice Chair: Lawrence Flynn (NOAA) products/new opportunities: Proposed projects up for consideration: 1. Reflectivity and Aerosol Index comparisons by using vicarious methods for ocean, desert and ice sheet targets. 2. Solar measurement comparisons by using high resolution reference data sets along with instrument bandpasses and Mg II scale factors. 3. Comparisons of radiance/irradiance measurements (240nm 290 nm) by using initial measurement residuals with respect to a priori ozone profiles [L. Flynn] 4. Identify calibration requirements and capabilities [R.Lang] Web meeting on use of hyperspectral reference instruments Definition of SBAF SNO Tying together other groups Slide: 16

17 New Prime GSICS Corrections Define one Primary GSICS Reference For each spectral band/application By consensus agreement within GSICS Use others as Transfer References Blend corrections from all references After modifying Corrections to Primary GSICS Reference Ensures long term continuity Without calibration jumps Ensures Traceability 40 back to single Primary Reference Simplifies users implementation Could also blend multiple methods? Slide: 17 ighting /% Wei Availability Modified of References Time /years Simple Weighting of Each Reference Time /years Mon Ref1 Ref2 Ref3 %Ref1 %Ref2 %Ref3

18 Correcting the Corrections and Blending References Reference-1 (Primary) Monitored Instrument Reference-2 (Secondary) Derived by GSICS GSICS Correction, g 1 Mon 1 Delta Correction, g 1/2 2 1 GSICS Correction, g 2 Mon 2 + g Prime GSICS Correction, g 0 Mon 1 Modified Correction, g 2,1/2 Mon 2 1 Slide: 18 Applied by User Mon Ref1

19 Users Application of Prime GSICS Correction Monitored Instrument Prime GSICS Correction, g 0 Mon 1 Slide: 19 Mon Ref1

20 GSICS Products Under Development GPRC Monitored Instrument Reference Instrument GSICS NRT Correction Re Analysis Correction Archive Re Calibration All All Current GEO imagers 0.6µm VIS channels Current GEO imagers 0.6µm VIS channels MODIS via DCC Demo 2014 Demo 2014 Demo 2014 MODIS via Moon Demo 2015 Demo 2015 Demo 2015 EUMETSAT Metop/AVHRR IASI EUMETSAT SCOPE CM Meteosat 2 10 } IR Meteosat 7 IASI AIRS, HIRS 2018 EUMETSAT SCOPE CM Meteosat 2 10 } VIS Meteosat 7 MODIS? 2018 NOAA AMSU/MSU NOAA14/AMSU In development Pre Operational In development NOAA TIROS N NOAA Patmos X Metop /AVHRR Aqua/MODIS Demonstration Full GSICS Product Catalog available at Slide: 20

21 Conclusions GSICS inter calibration products for IR channels of GEO imagers (prototype to pre op) VIS channels of GEO imagers by DCC (demo 2015) VIS/NIR channels of GEO+LEO imagers using Moon Prime GSICS Corrections will merge results from multiple reference instruments and maybe multiple methods and maybe multiple spectral bands Aim to simplify operational user implementation i Slide: 21

22 Thank You Any Questions? Slide: 22