anchor.diff:  C        D(2) - O NUMBER DENSITY(CM-3)
   C        D(3) - N2 NUMBER DENSITY(CM-3)
   C        D(4) - O2 NUMBER DENSITY(CM-3)
  -C        D(5) - AR NUMBER DENSITY(CM-3)                       
  +C        D(5) - AR NUMBER DENSITY(CM-3)
   C        D(6) - TOTAL MASS DENSITY(GM/CM3) [Anomalous O NOT included]
   C        D(7) - H NUMBER DENSITY(CM-3)
   C        D(8) - N NUMBER DENSITY(CM-3)
  
positive.code:       TZ=1./Y
        IF(XM.EQ.0.) GO TO 30
  C
  C      CALCULATE TROPOSPHERIC/STRATOSPHERE DENSITY 
  C     
        GLB=GSURF/(1.+Z1/RE)**2
        GAMM=XM*GLB*ZGDIF/RGAS
  C        Integrate temperature profile
  
negative.code: C          rather than at an altitude.
  C
  C        OUTPUT IN M-3 and KG/M3:   CALL METERS(.TRUE.)
  C
  C     INPUT VARIABLES:
  C        IYD - YEAR AND DAY AS YYDDD (day of year from 1 to 365 (or 366))
  C              (Year ignored in current model)
  