1. Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Double Differences of BTs in AVHRR Ch4 from MICROS Climate Quality Calibration for Generating Long-term Fundamental Climate Data Records from Optical Instruments (AVHRR/HIRS/IASI/GOES-R/CLARREO) C. Cao 1 (Government Principal Investigator), R. Chen 2, S. Uprety 3, L. Wang 3, A. Ignatov 1, X. Wu 1, A. Heidinger 1, P. Ciren 3, F.Yu 4, F. Kogan 1, W. Guo 2, F. Padula 5, B. Iacovazzi 4, M. Grotenhuis 4, and M. Goldberg 1 1 NOAA/NESDIS/STAR, 2 IMSG, 3 DPSGS, 4 ERT, 5 IAI Requirement: “ Sustaining production of satellite-based Climate Data Records which ensures the continuity of the climate record (historical and future) derived from satellite measurements that are needed to monitor and evaluate decadal to centennial climate change on a global scale.“- NOAA five research year plan Science: How can satellite data be accurately calibrated to meet the challenging requirements of climate change detection specified in GCOS? Benefit: Enable the detection of small signals of climate change with credible, consistent, and high quality long-term time series of satellite observations. Science Challenges: Producing climate quality long-term time series that meet the stability, accuracy, and consistency requirements for the detection of small signals of climate change. Next Steps: Establish climate quality stability standards, and make satellite observations traceable to SI (International System of Units). Transition Path: Develop & demonstrate innovative calibration techniques, publish peer reviewed papers, apply for funding, recalibrate historical data, contribute to the reanalysis and reprocessing for FCDRs. Goal: Develop more reliable 30+ yr HIRS Fundamental Climate Data Records Strategies: -Make HIRS/MetOP calibration traceable to IASI on MetOP -Make other HIRS traceable to MetOP/HIRS through SNO inter- calibration Progress: -Completed spectral bias study of HIRS using IASI (Cao, et al. 2008) -Analyzed relative bias between IASI and HIRS on MetOP -Results show most HIRS channels have excellent agreement with IASI, while some channels require spectral and radiometric recalibration Going forward: Develop comprehensive calibration model to make recalibrated HIRS traceable to IASI STAR Developed HIRS Long-term SNO Time Series for Consistent Inter-satellite Calibration Goals: –Assess the HIRS stability, and inter-satellite consistency for generating fundamental climate data records (FCDRs), and quantify the radiometric and spectral biases. –Establish and apply an accurate inter-satellite calibration procedure to develop inter-satellite calibration data sets, which will be useful for developing time series from historical NOAA satellite data –Ensure the calibration consistency and quality for long-term climate studies, facilitate the construction of long-term climate data records, and therefore reduce the uncertainties about critical climate trends. Strategies: –Inter-compare HIRS observations from different satellites at the SNOs –Evaluate the spectral and radiometric biases between satellites –Identify the stability characteristics of different HIRS channels Progress and going forward: –SNO time series developed from NOAA-6 to NOAA-18 and results confirmed through independent analysis –Large bias oscillation in some sounding channels while very stable for surface channel, caused by both natural differences and uncertainties in spectral response functions, in combination with the spectral features of the surface and atmosphere. –Identified candidate channels for phase 1 development of FCDRs –Tie HIRS calibration to other instruments such as AIRS, IASI, and CLARREO Improving the HIRS Fundamental Climate Data Records using IASI Recalibrating AVHRR Reflective Solar Bands for FCDRs Lunar NDVI & Dome C standards for climate change detection Goal: -Make operations satellite observations traceable to SI Strategies: -Calibrate NOAA satellites at the SNOs using CLARREO -Transition the CLARREO science to operations Progress and going forward: -Working closely with the CLARREO science team -A CLARREO compatible light version of the HIRS long-term time series is under development at STAR. MetOP IASI/HIRS footprint match-up Channel brightness temperature differences between MetOP IASI/HIRS for one selected orbit Spectral bias study of HIRS/NOAA6-18 using IASI Goals: -Resolve the disparities in the operational calibration of the AVHRR solar bands (up to 40% difference between satellites; operational Level 1b data not yet suitable for climate change detection) -Develop a consistent 30+ yr AVHRR solar band fundamental climate data record Strategies: -Establish stability standards such as MODIS/SeaWiFS, Dome C and lunar NDVI -Make AVHRR solar band calibration traceable to other instruments such as MODIS, stable targets such as Dome C, and/or the moon Progress: -Inter-comparison with MODIS reveals major discrepancies in traceability and standard -Good progress in desert based recalibration -Lunar NDVI technique demonstrated for NOAA-14 -Dome C standard is being established in collaboration with CEOS agencies Going forward: -Apply lunar calibration to all AVHRRs -Calibrate all AVHRR solar bands using Dome C -Revise AVHRR desert standard AVHRR lunar observations in the space view can be used to study instrument response and lunar band ratio drifts for climate change detection Lunar calibration applied to NOAA-14 NDVI time series and compared favorably to other calibrations Spectral characterization of Dome C and other vicarious sites using NASA’s Hyperion observations Inter-comparison of six radiometers at the Dome C site show AVHRR is biased low by 9% -The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a climate-focused mission, with the ability to produce irrefutable climate records through the use of exacting onboard traceability of calibration accuracy. -Spectral reflected solar and emitted infrared radiances and Global Positioning System (GPS) Radio Occultation refractivities measured by CLARREO will be used to detect climate trends and to test, validate, and improve climate prediction models. Developing Robust FCDRs by Making Satellite Measurements Traceable to On-orbit SI Standard Goal: -Assess the consistency of historical AVHRR infrared bands for generating fundamental climate data records. Strategies: -Inter-compare the channel brightness temperatures at the SNOs between NOAA satellites, and with MODIS Progress: - Completed the SNO bias assessment -Found discrepancies on the order of +/-1 K between satellites in historical data sets Going forward: - Resolve the intersatellite biases and make the calibration traceable to established standards such as IASI. -Validate the inter-satellite consistency using the MICROS (Monitoring of IR Clear-sky Radiances for SST) system as the test-bed Developed AVHRR Infrared Long-term SNO Time Series Developing Advanced Capabilities for GOES-R Goal: - Strive for climate quality & SI traceable calibration from the start. Strategies: -Leverage NIST technologies prelaunch (SIRCUS, TXR, SRF@cryogenic temperatures) -Leverage NASA advanced on-orbit technologies (hyperspectral reflective solar, solar diffuser, lunar, CLARREO) Progress: -Developed comprehensive cal/val plan -Developing advanced radiometric, spectral, and geo-spatial toolkits for GOES-R cal/val Selected publications: Cao, C., E. Vermote, X. Xiong, 2009, Using AVHRR Lunar Observations for NDVI Long-term Climate Change Detection, Journal of Geophysical Research, VOL. 114, D20105, doi:10.1029/2009JD012179, 2009 Cao, C., X. Xiong, A. Wu, and X. Wu, 2008, Assessing the consistency of AVHRR and MODIS L1B reflectance for generating fundamental climate data records, Journal of Geophysical Research, Vol.1, 113, D09114, doi:10.1029/2007JD009363, 2008 C. Cao, M. Goldberg, and L. Wang, Spectral Bias Estimation of Historical HIRS using IASI Observations for Improved Fundamental Climate Data Records, 2009, Journal of Atmospheric and Oceanic Technology, Vol.26, pp.1378-1387. Wang, L, and C. Cao, 2008, On-Orbit Calibration Assessment of AVHRR Longwave Channels on MetOp-A using IASI, IEEE Transactions on Geoscience and Remote Sensing, Vol. 46, No. 11, November 2008. Wang, L., C. Cao, and P. Ciren, 2007: Assessing NOAA-16 HIRS Radiance Accuracy Using Simultaneous Nadir Overpass Observations from AIRS. J. Atmos. Oceanic Technol., Vol. 24, No. 9, September 2007, 1546-1561. Cao, C., H. Xu, J. Sullivan, L. McMillin, P. Ciren, and Y. Hou, 2005, Intersatellite radiance biases for the High Resolution Infrared Radiation Sounders (HIRS) onboard NOAA -15, -16, and -17 from simultaneous nadir observations. Journal of Atmospheric and Oceanic Technology, 22, No. 4, pp. 381-395. Cao, C., M. Weinreb, and H. Xu, 2004, Predicting simultaneous nadir overpasses among polar-orbiting meteorological satellites for the intersatellite calibration of radiometers Journal of Atmospheric and Oceanic Technology, Vol. 21, April 2004, pp. 537- 542. A light version of HIRS/IASI data record is under development which focuses on CLARREO compatibility, re-calibration, and inter- calibration IASI traceable recalibratio n tested AVHRR/HIRS Infrared Channel Recalibration Roadmap Seasonal oscillation of inter- satellite biases in the long-wave CO 2 and water vapor channels Variable but stable bias in the surfaces channels benefit long-term time series analysis and useful for inter- channel calibration Spectral bias due to Spectral Response Function difference, spectral uncertainties, & lapse rate for upper atmosphere channels AVHRR SNO Time Series Orbital variation of biases between AVHRR and IASI on MetOP Calibration HDF files have been developed for both AVHRR and HIRS for selected satellites for inter- sensor calibration Large discrepancies in AVHRR solar band calibration affects both reflectance and NDVI trends Erroneous NDVI trend Large discrepancies in reflectance Reducing spectral uncertainties with NIST filter measurements Sensitivity analysis with the Spectral Calibration Analysis Toolkit ABI band ratio analysis using Hyperion Lunar observations Geo-spatial toolkit for MTF/ PSF, co-registration, and navigation analysis Calibration HDF Toolkits development Comprehensive cal/val plan AVHRR Solar Band Recalibration Roadmap