TITLE: INDOEX: Aircraft C-130 Radiation Actinic Flux Spectroradiometer (Campos) AUTHOR(S): Teresa L Campos and Richard E Shetter NCAR Atmospheric Chemistry Division PO Box 3000 Boulder, CO 80307-3000 Phone: 303-497-1879 Fax: 303-497-1411 campos@acd.ucar.edu shetter@acd.ucar.edu 1.0 - 3.0 DATA SET SUMMARY AND INSTRUMENT DESCRIPTION: The NCAR C-130 platform measured spectrally resolved solar flux. Two spectroradiometers were integrated in zenith and nadir locations to provide upwelling, downwelling and total actinic flux spectra. Photographs of the zenith and nadir spectroradiometer installations are shown in Figures 1 and 2, respectively. The collection optics and shadow rings were configured to match the heights of other radiometric instruments installed on the aircraft. Due to a shortage of seats available on research flights, the instrument was designed to operate unattended once power had been supplied to the instrument. Dr. Campos also operated the instruments on ferry flights from Boulder to Male; these data are available upon request to the principle investigators. The spectroradiometric method referenced in Shetter and Muller [1999] was modified to provide actinic flux spectra over the extended wavelength range of 300 to 920 nm with a 0.25-Hz time response, employing a diode array spectrometer. The hemispherical quartz collection optics were implemented as described in Shetter and Muller. Figure 3 illustrates the typical angular response over 2(-steradian of each hemispheric collection optic. Data coverage during the INDOEX intensive was better than 98% for C-130 research flights (16 February, 1999 through 25 March, 1999). Figure 1 (http://www.joss.ucar.edu/data/indoex/docs/c130.afs.fig1.gif) Figure 2 (http://www.joss.ucar.edu/data/indoex/docs/c130.afs.fig2.gif) Figure 3 (http://www.joss.ucar.edu/data/indoex/docs/c130.afs.fig3.gif) The performance specifications were established to enable acquisition of actinic flux spectra covering the range from 300 to 920 nm with a resolution of 3 nm (FWHM). The wavelength-dependent instrument response function was determined approximately to have the shape of a smoothed triangle, so the detection limit for actinic flux measurement was approximately 0.5 (W/cm2-nm at 300 nm and approximately 0.1 at 600 nm. 4.0 DATA FORMAT: Data file structure: space delimited ASCII File naming convention: c130.afs.yymmdd_sum_tot.flx Header: No Header Equivalent Header Information: PI/DATA CONTACT= Campos, Teresa (NCAR), Shetter, Rick (NCAR) PLATFORM/SITE = C130 INSTRUMENT = C-130 total actinic flux spectra DATA VERSION = 1.0 (25 March 2000), FINAL REMARKS = National Center for Atmospheric Research, INDOEX REMARKS = Data point Time provided in UTC in hh:mm:ss format REMARKS = Missing data = -9999; Bad data = -9999 File Parameters: UTC (time, hh:mm:ss) Wavelength (nm) Actinic Flux (photons/cm2/s-1/nm) Version number: 1.00, 25 March 2000, FINAL DATA Missing and Bad Data Flag: -9999. REFERENCES B Shetter, Richard E and Martin Muller, 1999, "Photolysis frequency measurements using actinic flux spectroradiometry during the PEM-Tropics mission: Instrumentation description and some results," Journal of Geophysical Research, 104(5), 5647.