SUBROUTINE rcal_n18 (date,rcal) c Day-1 N18 radiance calibration constants integer*4 date real*4 rcal(13),rcaln1(13) c The prelaunch (Apr 2003) calibration was used during the A&E. c They are corrected for wavelength shift by interpolation of calcons c in the sweep mode. Details in DeLand's "SBUV/2 FM#7 Prelaunch I c nstrument Characterization for NOAA-N", 28 Jan 2005 c data rcaln1/1.3642e-04,1.2857e-04,1.4484e-04,1.4045e-04, c + 1.3143e-04,1.2278e-04,1.1842e-04,1.1579e-04,1.1119e-04, c + 1.0643e-04,9.2728e-05,8.5641e-05,7.4116e-03/ c Just another version of prelaunch calcons from DeLand, 2 August 2006, c due to round off? with < 0.2% difference. (t3m) c data rcaln1/1.3644E-04,1.2901E-04,1.4507E-04,1.4080E-04, c + 1.3162E-04,1.2296E-04,1.1870E-04,1.1607E-04,1.1144E-04, c + 1.0661E-04,9.2827E-05,8.5797E-05,7.4116E-03/ c --- Revised rcal and flux as in A&E report to keep the same prelaunch albedo c calibration, and to match the solar flux with the SSBUV2 solar flux c calibration. --- LKH Nov 2005 c data rcaln1/1.4710E-04,1.4223E-04,1.5595E-04,1.4870E-04, c + 1.3912E-04,1.3076E-04,1.2564E-04,1.2294E-04,1.1667E-04, c + 1.1063E-04,9.4479E-05,8.8328E-05,8.0171e-03/ c c --- Solar irradiance was reprocessed with the measured gain ratios in earth c view which have small offsets from the average. As the solar irradiance c are attached to SSBUV-2 values, the irradiance and radiance calibration c constants are revised. The maximum change of -0.36% is at channel 10. c DeLand 1/13/2006 and 2/21/2006 e-mail. --- LKH Mar 2006 c data rcaln1/1.4686E-04,1.4202E-04,1.5571E-04,1.4846E-04, c + 1.3890E-04,1.3054E-04,1.2544E-04,1.2268E-04,1.1666E-04, c + 1.1023E-04,9.4442E-05,8.8216E-05,8.0171E-03/ c cc --- Scale down by 6% at 252 nm and 2% at 340 nm, and linearly interpolated cc the scale between. Scaled CCR down by 1.0318. DeLand 8/11/06 e-mail. c data rcaln1/1.3861E-04,1.3527E-04,1.4890E-04,1.4224E-04, c + 1.3335E-04,1.2561E-04,1.2093E-04,1.1846E-04,1.1298E-04, c + 1.0697E-04,9.2201E-05,8.6446E-05,7.7700E-03/ c c --- Reprocessed solar irradiance with LKH's goniometry correction factor, which c increased ~8% mainly due to a sign change of the prelaunch calibration c elevation angle. (t3h) --- LKH Aug 04, 2006. c data rcaln1/1.3435E-04,1.2868E-04,1.4263E-04,1.3516E-04, c + 1.2624E-04,1.1918E-04,1.1447E-04,1.1169E-04,1.0591E-04, c + 1.0007E-04,8.6064E-05,8.1106E-05,7.1681E-03/ c c --- CalCons based on 1998 albedo calibration. The 8/11/06 irradiance c counts at elevation angle of +1.544 degrees are recovered from the scale c factors, SSBUV-2 solar irradiance, and the A&E year 2003 irradiance c CalCons. Then, the counts are renormalized to that at elevation angle c of -0.766667 degrees. The 1998 irradiance CalCons are corrected for the c diffuser reflectivity changes from that time to A&E, then, applied to c the irradiance. The scale factors to SSBUV-2 are 1.0300,1.0438,1.0121, c 0.9941,0.9924,0.9982,0.9938,0.9938,0.9836,0.9722,0.9584,0.9712,1.0599. c The following radiance CalCons are the product of the scale factors and c 1998 radiance CalCons. --LKH, May 2008 c c data rcaln1/1.3259E-04,1.2975E-04,1.4257E-04,1.3626E-04, c + 1.2787E-04,1.2041E-04,1.1584E-04,1.1342E-04,1.0796E-04, c + 1.0205E-04,8.7352E-05,8.1530E-05,7.3210E-03/ c --- Iterated from the V6 and V8 process using the above flight diffuser c reflectivity adjusted 1998 albedo calibration. Comparison with N17 s4 c version (ACF normalized to 1/g(t=Solar Day1)) shows an average offset c of -4.67% at the 4 shortest wavelength (in V8 IPR) and -3.91% in c Antarctic snow/ice reflectivity at 331 nm. Thus, the above radiance c calibration constants are adjusted by +4.288%. c data rcaln1/1.3827E-04,1.3531E-04,1.4868E-04,1.4210E-04, c + 1.3335E-04,1.2557E-04,1.2081E-04,1.1829E-04,1.1259E-04, c + 1.0642E-04,9.1098E-05,8.5026E-05,7.6350E-03/ c c --- The 1998 calibration constants are used to process the solar irradiance. c Ratios of the resulted solar irradiance to the SSBUV-2 solar irradiance c are used as the scale factor for the radiance calibration constants to c maintain the 1998 albedo calibration. c data rcaln1/1.2994E-04,1.2745E-04,1.4002E-04,1.3382E-04, c + 1.2557E-04,1.1825E-04,1.1375E-04,1.1137E-04,1.0601E-04, c + 1.0020E-04,8.5783E-05,8.0067E-05,7.2271E-03/ c --- The above 1998 calibration constants have to be increased by a c multiplication factor of 1.055 which makes channels 1-5 IPR in agreemnet c with N17s3e. In fact, this adjustment makes N18 Antarctic snow/ice c reflectivity in good agrrement with N17s3e, as well as in c C-sigma analysis with both N16p1e and N17s3e. --LKH, Nov 2008 data rcaln1/1.3709E-04,1.3445E-04,1.4772E-04,1.4118E-04, + 1.3248E-04,1.2475E-04,1.2000E-04,1.1750E-04,1.1184E-04, + 1.0571E-04,9.0501E-05,8.4471E-05,7.6246E-03/ do 100 i=1,13 100 rcal(i)=rcaln1(i) return end