VOL. 14: The First SeaWiFS Intercalibration Round-Robin Experiment, SIRREX, July 1992.
Citation:
Mueller, J.L., 1993: The First SeaWiFS Intercalibration Round-Robin Experiment,
SIRREX, July 1992. NASA Tech. Memo. 104566, Vol. 14, S.B. Hooker and E.R.
Firestone, Eds., NASA Goddard Space Flight Center, Greenbelt, Maryland, 60 pp.
This report presents the results of the first Sea-viewing Wide Field-of-view
Sensor (SeaWiFS) Intercalibration Round-Robin Experiment (\SIRREX), which was
held at the Center for Hydro-Optics and Remote Sensing (CHORS) at San Diego
State University (SDSU) on 27--31 July 1992. Oceanographic radiometers to be
used in the SeaWiFS Calibration and Validation Program will be calibrated by
individuals from the National Aeronautics and Space Administration's (NASA)
Goddard Space Flight Center (GSFC), CHORS, and seven other laboratories. The
purpose of the SIRREX experiments is to assure the radiometric standards used in
all of these laboratories are referenced to the same scales of spectral
irradiance and radiance, which will be maintained by GSFC and periodically
recalibrated by the National Institute of Standards and Technology (NIST). The
spectral irradiance scale of GSFC's FEL lamp number F269 (recalibrated by NIST
in October 1992) was transferred to lamps belonging to the 9 participating
laboratories; 1 set of lamp transfer measurements (involving 4 of the lamps) was
precise to within less than 1% and meets SeaWiFS goals, but a second set
(involving another 14 lamps) did not. The spectral radiance scale of the GSFC
40-inch integrating sphere source was transferred to integrating sphere radiance
sources belonging to four of the other laboratories. Reflectance plaques, used
for irradiance-to-radiance transfer by five of the laboratories, were compared,
but spectral bidirectional reflectance distribution functions (BRDFs) were not
determined quantitatively. Also reported here are results of similar comparisons
(in October 1992) between the GSFC scales of spectral irradiance and radiance
and those used by the Hughes/Santa Barbara Research Center (SBRC) to calibrate
and characterize the SeaWiFS instrument. This first set of intercalibration
round-robin experiments was a valuable learning experience for all participants,
and led to several important procedural changes, which will be implemented in
the second SIRREX, to be held at CHORS in June 1993.
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