GOES-8 through GOES-15 Imager Spectral Response Functions
(Revised, August 2011)
The latest versions of GOES-8 through GOES-15 Imager spectral response functions (SRFs) are available for download. All of them were provided by ITT (the instruments' manufacturer), except those noted as modified by STAR.
1 Note: The GOES-13,14,15 Imager SRFs are the same in ITT releases Rev. E, 2008 and Rev. F, 2010.
GOES-13 Imager History
Note that three versions of the spectral response functions (SRFs) for channel 6 (13.3
microns central wavelength) of the GOES-13 Imager are presented within the links and tables on this website, along
with the related calibration parameters associated with each SRF version. These different
SRFs have come about due to the identification of a cold bias in the brightness temperatures
of the channel 6 images before GOES-13 went into operation as GOES-EAST.
Version 1: Original (Release Rev.D, 2005)
The original channel 6 SRFs provided by the instrument vendor, ITT, were used during the GOES-13
post-launch tests in 2006 when a cold bias of -2.4±0.6 K in the channel 6 imagery was reported by
the CIMSS group at University of Wisconsin. The cold bias was identified via comparisons with high
spectral resolution Atmospheric InfraRed Sounder (AIRS) data on Aqua, comparisons with High-resolution
Infrared Radiation Sounder (HIRS) data on NOAA-15 and NOAA-16 and a limited number of forward model
comparisons. The cold bias is consistent with a central-wavenumber shift on the order of -4 cm-1
(towards longer wavelengths) with respect to the original channel 6 SRFs. The original (Rev.D) channel 6
SRFs are included in the above GOES-13 download
link, and they have been used for all GOES 13 Imager calibration processing before Aug. 1, 2008 (including Post Launch Testing and the NOAA Science Test).
Version 2: ITT Updated (Release Rev.E1, 2008)
In response to the cold bias detected in channel 6 imagery during post-launch testing, ITT re-evaluated
the pre-launch test data and provided updated SRFs for channel 6 which shifted their effective central
wavenumbers by about -1.2 cm-1 (towards longer wavelengths). The ITT-updated SRFs are included in the
above GOES-13 download link and the Calibration and Alignment Handbook information for GOES-13. The ITT Rev.E SRFs were used for all GOES 13 Imager calibration processing from Aug. 1, 2008 to March 26, 2009.
Version 3: STAR Updated – Currently Operational
NOAA/STAR has evaluated the original cold bias findings, and it has also analyzed a set of observational
comparisons with both AIRS and IASI data for year 2008. This has led to another update to the channel 6
SRFs which shifts the ITT updated SRFs by a further -2.1 cm-1 (towards longer wavelengths). Thus the
STAR-updated SRFs have a total effective shift of about -3.3 cm-1 with respect to the original channel 6 SRFs.
The STAR-updated SRFs are included in the above GOES-13
download link, and they have been used for all GOES 13 Imager calibration processing after March 26, 2009.
The updated shifted GOES-13 Imager channel-6 SRF reduces the overall cold bias. Users need to adjust their
conversion from radiance to brightness temperature for this channel. For each of these SRF versions, the GOES Calibration web site contains all of the coefficients for Conversion of GVAR Infrared Data to Scene Radiance or Temperature for GOES-13 Imager channel 6.
GOES-14 Imager SRF History
Note that three versions of the spectral response functions (SRFs) for the GOES-14 Imager are presented on
this website, along with the related calibration parameters associated with each SRF version. These different
SRFs correspond to different releases of the Calibration and Alignment Handbook by the instrument vendor ITT.
Release Rev.D – Discontinued on Nov. 24, 2009
These are the SRFs provided by the instrument vendor in Release 2005, Rev D. They have been used for all GOES
14 Imager calibration processing before Nov. 24, 2009 (when GOES-14 was undergoing Post Launch Testing, but
before the NOAA Science Tests).
Release Rev.E1 – Discontinued Aug. 9, 2011
These are the SRFs provided by the instrument vendor in Release 2008, Rev E. They have been used
for all GOES 14 Imager calibration processing between Nov. 24, 2009 (including the very end of Post Launch Testing
and including the NOAA Science Tests) and August 09, 2011.
Release RevH plus STAR correction – Currently Operational
These are the SRFs provided by the instrument vendor in Release Rev H, 2011, except in IR channels 3 and 6 where the original RevH SRFs have been shifted by -8.25 cm-1 and -0.25 cm-1 wavenumbers, respectively. The shifts to the channel 3 and channel 6 SRFs are the results of studies by NOAA/STAR using GSICS and other inter-calibration techniques which detect scene brightness-temperature biases between the GOES-14 post-launch NOAA Science Test data and the IASI instrument. These SRFs will be used for all GOES-14 Imager calibration processing starting after Aug. 09, 2011.
GOES-15 Imager SRF History
Release Rev E1 – Discontinued Aug. 9, 2011
These are the SRFs provided by the instrument vendor in Release 2008, Rev E. They have been used for all GOES 15
Imager calibration processing before Aug. 09, 2011 (including Post Launch Testing and the NOAA Science Tests).
Release RevH plus STAR correction – Currently Operational
These are the SRFs provided by the instrument vendor in Release Rev H, 2011, except in IR channels 3 and 6 where the original Rev H SRFs have been shifted by -6.25 cm-1 and +0.50 cm-1 wavenumbers, respectively. The shifts to the channel 3 and channel 6 SRFs are the results of studies by NOAA/STAR using GSICS and other inter-calibration techniques which detect scene brightness-temperature biases between the GOES-15 post-launch NOAA Science Test data and the IASI instrument. These SRFs will be used for all GOES-15 Imager calibration processing starting after Aug. 09, 2011.