Contents of listing files for SBUV PMC scan data
   ================================================

   File name convention:
         [satellite]_[hemisphere][year(s)][calibration]_sig1p3_allwv.dat

	satellite:  'n07' = Nimbus-7 SBUV, 'n09' = NOAA-9 SBUV/2, ...
	hemisphere:  'nh' = Northern Hemisphere.  Season = (solstice - 30 days) 
			     to (solstice + 70 days) = day 142 to day 242.
		     'sh' = Southern Hemisphere.  Season = (solstice - 30 days) 
			     to (solstice + 70 days) = day 325 (year 1) to 
                             day 60 (year 2).
	year(s):  Note that nominal Southern Hemisphere season starts in one 
                    calendar year and ends in the next year.
	calibration:  Tag identifying instrument calibration version for ozone 
                        processing.
        sig1p3:  Scale factor for latitude-dependent noise threshold test.
        allwv:  Albedo information for all test wavelengths listed.


Column  Information
######  ###########
    1   Satellite number [7, 9, ...]
    2   Year
    3   Day of year
    4   Day from solstice for current season
    5   Measurement time [seconds UT]
    6   Mean local solar time (longitude-corrected) [hours]
    7   Latitude [degrees];  negative = S. Hem., positive = N. Hem.
    8   Longitude [degrees];  positive = East, negative = West
    9   Solar zenith angle [degrees]
   10   Orbit flag;  0 = ascending node, 1 = descending node
   11   Background fit albedo at 252.0 nm (corrected for Rayleigh scattering, 
           phase function)
   12   Residual albedo at 252.0 nm (data - 4th order fit)
   13   Residual albedo at 252.0 nm [percent]
14-16   Background fit albedo, residual albedo, percent residual for 273.5 nm
17-19   Background fit albedo, residual albedo, percent residual for 283.1 nm
20-22   Background fit albedo, residual albedo, percent residual for 287.6 nm
23-25   Background fit albedo, residual albedo, percent residual for 292.3 nm
   26   Slope vs. wavelength of absolute albedo residuals [1/nm]
   27   Error of slope for residual regression fit
   28   PMC test summary flag;  31 = good detection, -1 = screened scan


PMC test flag components
++++++++++++++++++++++++
  T0 = 16:  r252 exceeds threshold [always set in current data]
  T1 =  8:  r252, r273, r283 > 0.0
  T2 =  4:  m_lambda < 0.0
  T3 =  2:  r252 > [scale_factor*sigma_252(latitude)]
  T4 =  1:  r252 > r273

FLAG = T0 + T1 + T2 + T3 + T4

r252          =  residual albedo at 252 nm
m_lambda      =  slope of regression fit to albedo residuals
scale_factor  =  1.3
sigma_252     =  quadratic fit in latitude to 252 nm residuals from non-PMC data