Cooperative Institute for Climate and Satellites University of Maryland 5825 University Research Court, (Suite 4001) College Park, MD 20740-3823 Tel: (301) 405-2147 Fax: (301) 405- Institute Director: Dr. Phillip Arkin [email protected]Assistant Director: Andrew Negri [email protected]A Fundamental Climate Data Record for the AVHRR Jonathan Mittaz Manik Bali & Andrew Harris CICS/ESSIC University of Maryland
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A Fundamental Climate Data Record for the AVHRR Jonathan Mittaz Manik Bali & Andrew Harris CICS/ESSIC University of Maryland.
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A Fundamental Climate Data Record for the AVHRR
Jonathan MittazManik Bali & Andrew Harris
CICS/ESSICUniversity of Maryland
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Funded project through NCDC for 3 years (part of NOAA Climate Data Record Program)
Goal To provide recalibrated AVHRR Level 1B radiances for the thermal IR
channels (3.7, 11 and 12 μm channels) which are as accurate and bias free as possible and where the uncertainty on the radiances are better understood.
Source Data NOAA AVHRR Level 1B data
Deliverables – not yet fully defined by likely to be one or more of Code to calculate new radiances from current AVHRR Level 1B files Recalibrated Level 1B data files (all AVHRRs in KLM format) NCDC specific format (netCDF for example)
Part of SW/IR Imager FCDR Team – Team Lead : Bob Evans
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Example of pre-launch problems (Mittaz, Harris & Sullivan)
Application of the Walton et al. calibration on the pre-launch data from which it was derived shows large biases – sign of severe problems with the pre-launch data and methodology
Can be fixed by the use of a physically based methodology – means that all pre-launch data has to be re-analyzed
Some pre-launch calibration parameters will still be corrupted
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
• Use Physically based calibration equation (pre-launch and TOA)
• Use Top Of Atmosphere calibration sources (e.g. (A)ATSR, IASI etc.) when available to correct parameters contaminated during pre-launch testing (underlined in red)
• Use model of instrument to obtain calibration when contamination exists (solar contamination) when possible
• Remove periods of bad calibration from record• Monitor calibration as a function of time and correct when necessary
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
• Baseline instrument for re-calibration is the (A)ATSR series– Designed to be climate ready– Accurate and stable to < 0.05K (apart from the AATSR 12µm channel see later)– Data available from 1991 to present day (covers the AVHRR/2 AVHRR/3
instruments)• Data available via FTP
– One months worth of data ~130Gbytes – takes ~ 3 days to download• AVHRR data matched with (A)ATSR data (first attempt parameters)
– Match individual AVHRR GAC ‘pixels’– Take into account true AVHRR GAC footprint– Both AVHRR and (A)ATSR data should be spatially coherent (current limit σ<1K
over ~12x12km area)– Satellite ZA agree to < 1°– Data limited to close to nadir (current limit < 10°)– For daytime 3.7µm channel keep relative azimuth angle to < 30°– Maximum time difference between AVHRR and (A)ATSR data < 10 minutes – Correct (A)ATSR data for differences in spectral response functions
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
• In Operation since March 2001 – thought to currently have a bad calibration (e.g. ‘out of family’ from NOAA MICROS pages).- test case for AVHRR near terminator/problem checking
AATSR/NOAA-16 AVHRR Comparison (11µm)
Using calibration from MetOp-A gives a trend and bias(but smaller trends than current calibration)(Data from Feb 2003)
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Unlike MetOp-A (0.2K in 4 years), NOAA-16 shows large temperature variations – becomes extreme from ~ 2008. A change in the thermal environment may explain the change in the 2010 calibration biases relative to 2003.
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
Cooperative Institute for Climate and SatellitesUniversity of Maryland5825 University Research Court, (Suite 4001)College Park, MD 20740-3823Tel: (301) 405-2147 Fax: (301) 405-8648http://www.essic.umd.edu/cics
• For future missions - good pre-launch testing is critical and needs to be done properly• In orbit comparisons against TOA reference sources is also critical to remove biases
– Most of the tools are in place to recalibrate AVHRR/3 series• AVHRR/2 waiting on pre-launch analysis
• AVHRR has the capability of being used for accurate climate studies – MetOp-A is currently accurate and stable
• Requirement for time/temperature dependence for the calibration– Clear in NOAA-16 (calibration very different in 2010 compared to 2003– Constant instrument temperature -> constant calibration? (MetOp-A)
• Need to remove accurately remove/estimate bad data from record– Tools are in place
• Remaining issues– SRF shift needs to be included for (A)ATSR data– 3.7 µm channel
• Automatic implementation of Earthshine correction – AATSR 12 µm channel needs to be fixed– Look into using RTM data/AVHRR overlap periods when accurate TOA sources not available