Contents of Level 2 files for OMPS NP PMC individual scan data
   ==============================================================

   File name convention:
         [satellite]_[procver]_[hemisphere][year(s)]_sza_iwc.dat

	satellite:   'snpp' = Suomi NPP, 'n20' = NOAA-20
	procver:     Processing version of OMPS NP Level 2 data [NPBUVO3-L2]
	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.

        NOTE:  The JPSS-1 satellite was renamed to NOAA-20 after it reached orbit

Column  Information
######  ###########
    1   Satellite number [1=S-NPP, 20=NOAA-20]
    2   Year
    3   Day of year
    4   Day from solstice for current season
    5   Orbit number
    6   Measurement time [seconds UT]
    7   Mean local solar time (longitude-corrected) [hours]
    8   Latitude [degrees];  negative = S. Hem., positive = N. Hem.
    9   Longitude [degrees];  positive = East, negative = West
   10   Solar zenith angle [degrees]
   11   Orbit flag;  +1 = ascending node, -1 = descending node
   12   Background fit albedo at 252.0 nm [sr^-1]
   13   Residual albedo at 252.0 nm (data - 4th order fit) [sr^-1]
   14   Background fit albedo at 273.5 nm  [sr^-1]
   15   Residual albedo at 273.5 nm (data - 4th order fit) [sr^-1]
   16   Background fit albedo at 283.1 nm  [sr^-1]
   17   Residual albedo at 283.1 nm (data - 4th order fit) [sr^-1]
   18   Calculated ice water content using 273.5 nm residual albedo [gm/km^2]
   19   PMC test summary flag;  31 = good detection 
                               -31 = screened detection

NOTE:  For NP instruments, scattering angle = (180.0 - solar zenith angle)

PMC test flag components
++++++++++++++++++++++++
FLAG = T0 + T1 + T2 + T3 + T4

  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(SZA)]
  T4 =  1:  r252 > r273

   r252          =  residual albedo at 252 nm
   m_lambda      =  slope of regression fit to albedo residuals
   scale_factor  =  1.0
   sigma_252     =  quadratic fit in SZA to 252 nm residuals from non-PMC data

   FLAG = -31:  Scan met requirements for original PMC detection algorithm, 
                but did not satisfy further screening tests for trend analysis 
                described in DeLand and Thomas [2015, JGR Atmospheres]