RFM File Formats

.pth File: Path Diagnostics

19NOV17

Type
Output(s), if PTH Flag enabled.

Description
Ray tracing and Curtis-Godson integration diagnostics

Filename(s)
Default is pth_[t].asc where [t] is the ray path.
Different names may be specified in the *PTH section of the Driver Table.

Structure
!HEADER1
!HEADER2
[!HEADER3] [Limb viewing only]
[! RFRTAN GEOTAN ZENTAN PSITAN RADCRV ELEOBS ALTOBS PSIOBS] [Limb viewing only]
NGAS NSEG1 NSEG2 '= NGas, NSeg1, NSeg2'
GAS(i) [Start repeat for i=1:NGAS]
!HEADER5
LEV(j) ALT(j) ANG(j) PRE(j) TEM(j) VMR(j) AMT(j) LEN(j) FLG(j) [Repeat for j=1:NSEG1]
'Total:' TOTAMT TOTLEN
[!HEADER5] [If GRA Flag enabled ...]
[ LEV(j) ALT(j) ANG(j) PRE(j) TEM(j) VMR(j) AMT(j) LEN(j) FLG(j) ] [Repeat for j=NSEG2:1]
['Total:' TOTAMT TOTLEN] [End repeat for i]
[eof]

Fields
FieldTypeDescriptionRange
!HEADER1 C*80 Contains ray path identification and RFM version
!HEADER2 C*80 Text read from *HDR section of Driver Table
!HEADER3 C*80 Text column headers for next record Only for limb-viewing
RFRTAN R*8 Refracted Tangent Height [km]
GEOTAN R*8 Geometric Tangent Height [km]
ZENTAN R*8 Zenith Angle at Tangent Pt [deg]
PSITAN R*8 Line-of-Sight Angle at Tangent Pt [deg] Or blank if unspecified
RADCRV R*8 Radius of Curvature [km]
ELEOBS R*8 Observer Elevation Angle [deg]
ALTOBS R*8 Observer Altitude [km] Or blank if unspecified
PSIOBS R*8 Observer LOS Angle [deg] Or blank if unspecified
NGAS I No.of different molecules
NSEG1 I No.of path segments for ray on downward path
GAS C*7 Name of molecule
!HEADER4 C*80 Text column headers for next record
LEV I Atmospheric Profile Layer# same for all molecules
ALT R*4 Altitude [km] of segment lower boundary same for all molecules
ANG R*4 Zenith or (GRA Flag) LOS angle [deg] Edge of seg nearest obs.
PRE R*4 Curtis-Godson Pressure [mb]
TEM R*4 Curtis-Godson Temperature [K]
VMR R*4 Volume Mixing Ratio [ppv]
AMT R*4 Absorber Amount [kmol/cm2]
LEN R*4 Path Length [km] same for all molecules
FLG I Flag 1=explicitly calculuated, 0=scaled
TOTAMT R*4 Total Amount in path [kmol/cm2]
TOTLEN R*4 Total Length of path [km] same for all molecules

Notes
  1. !HEADER3 and the following record are only generated for limb-viewing mode, ie not with HOM NAD or ZEN Flags.
  2. ! RFRTAN ... the record starts with an exclamation mark, ie notionally a comment record since its contents are not required to read the rest of the file. The RFRTAN field is written with F9.3 but the other fields are all written F10.3 (so a particular field occupies the same 10-character position whatever options have been used).
  3. ZENTAN is 90 for a 'true' tangent point, but if the ray intersects the surface or for an upward-viewing limb observation then the angle between the ray and the local vertical (<90) is given instead
  4. PSITAN is left blank unless the GRA Flag is enabled, ELEOBS and ALTOBS are left blank unless the OBS Flag is enabled, and PSIOBS is left blank unless both the GRA and OBS Flags are enabled.
  5. NSEG1,NSEG2: the ray-tracing starts at the observer and proceeds away through the atmosphere downwards first, then upwards, although either the upwards or downwards components may be absent for particular viewing geometries. If the atmosphere is horizontally homogeneous (ie unless the GRA Flag is enabled) the ray-tracing diagnostics are only listed for one of the two parts of the path (whichever spans most atmospheric layers).
  6. Note that while ALT is defined for the lower of the two segment boudaries, ANG is defined for the edge furthest from the observer, so, for a given atmospheric level LEV, the two ALT values will be the same while the two ANG values will be different.
  7. Enabling the CLC Flag will result in all FLG values being set to 1
  8. TOTAMT and TOTLEN refer only to the part of the path listed above, ie represent an addition of all the column entries.

Examples
Limb viewing, co2 and o3
! Path diagnostics calculated for Tan Hgt=   5.000 [km] by RFM v.4.09
! 27-APR-00 demo
!  Rfr.Tan   Geo.Tan   Tan.Zen   Tan.Psi   Rad.Crv   Obs.Ele   Obs.Alt   Obs.Psi
!    5.000     6.044    90.000            6367.421
           1          44           0 = NGas, NSeg1, NSeg2
co2
Lev  Zlow[km]  Zen[dg] Temp[K]  Press[mb]  VMR[ppv]   Amt[kmol/cm2] Len.[km] Clc
 49  115.000   79.245  326.069 3.31580E-05 3.79538E-05 1.21510E-13    27.087  1
 48  110.000   79.480  264.033 5.71787E-05 5.21933E-05 3.45144E-13    27.700  1
 47  105.000   79.721  220.677 1.12542E-04 9.11163E-05 1.37424E-12    28.358  1
...etc
  8    7.000   88.332  239.623 3.84607E+02 3.30000E-04 2.40937E-05    37.871  1
  7    6.000   88.641  246.198 4.43279E+02 3.30000E-04 3.53086E-05    49.470  1
  6    5.000   89.041  253.598 5.17799E+02 3.30000E-04 9.69768E-05   119.815  1
                                                Total: 2.47250E-04  1248.007
o3
Lev  Zlow[km]  Zen[dg] Temp[K]  Press[mb]  VMR[ppv]   Amt[kmol/cm2] Len.[km] Clc
 49  115.000   79.245  316.979 3.54397E-05 3.07916E-09 7.04431E-18    27.087  1
 48  110.000   79.480  256.459 6.12180E-05 3.15013E-08 1.52709E-16    27.700  1
 47  105.000   79.721  218.963 1.16757E-04 1.41958E-07 1.89773E-15    28.358  1
...etc
  7    6.000   88.641  246.091 4.42272E+02 4.51605E-08 4.82731E-09    49.470  1
  6    5.000   89.041  253.548 5.17271E+02 3.87587E-08 1.13941E-08   119.815  1
                                                Total: 2.33307E-07  1248.007
[eof]

Limb viewing, co2 only, with GRA Flag enabled (horizontal gradient mode, although no gradient applied hence down and up paths identical apart from Psi angle).
! Path diagnostics calculated for Tan Hgt=   5.000 [km] by RFM v.4.09
!27-APR-00
!  Rfr.Tan   Geo.Tan   Tan.Zen   Tan.Psi   Rad.Crv   Obs.Ele   Obs.Alt   Obs.Psi
!    5.000     6.044    90.000     0.000  6367.421
           1          44          44 = NGas, NSeg1, NSeg2
co2
Lev  Zlow[km]  Psi[dg] Temp[K]  Press[mb]  VMR[ppv]   Amt[kmol/cm2] Len.[km] Clc
 49  115.000   11.091  326.069 3.31580E-05 3.79538E-05 1.21510E-13    27.087  1
 48  110.000   10.856  264.033 5.71787E-05 5.21933E-05 3.45146E-13    27.700  1
 47  105.000   10.615  220.677 1.12542E-04 9.11164E-05 1.37425E-12    28.358  1
...etc
  8    7.000    1.862  239.623 3.84607E+02 3.30000E-04 2.40952E-05    37.873  1
  7    6.000    1.522  246.198 4.43280E+02 3.30000E-04 3.53127E-05    49.476  1
  6    5.000    1.077  253.597 5.17796E+02 3.30000E-04 9.69509E-05   119.784  1
                                                Total: 2.47231E-04  1247.991
  6    5.000    0.000  253.597 5.17796E+02 3.30000E-04 9.69509E-05   119.784  1
  7    6.000   -1.077  246.198 4.43280E+02 3.30000E-04 3.53127E-05    49.476  1
  8    7.000   -1.522  239.623 3.84607E+02 3.30000E-04 2.40952E-05    37.873  0
...etc
 47  105.000  -10.368  220.677 1.12542E-04 9.11164E-05 1.37425E-12    28.358  0
 48  110.000  -10.615  264.033 5.71787E-05 5.21933E-05 3.45146E-13    27.700  0
 49  115.000  -10.856  326.069 3.31580E-05 3.79538E-05 1.21510E-13    27.087  0
                                                Total: 2.47231E-04  1247.991
[eof]

Zenith viewing, co2 only
! Path diagnostics calculated for AirMass=   1.000      by RFM v.4.09
! 27-APR-00 demo
           1          49           0 = NGas, NSeg1, NSeg2
co2
Lev  Zlow[km]  Zen[dg] Temp[K]  Press[mb]  VMR[ppv]   Amt[kmol/cm2] Len.[km] Clc
  1    0.000  180.000  285.015 9.55900E+02 3.30000E-04 1.32985E-06     1.000  1
  2    1.000  180.000  278.516 8.46900E+02 3.30000E-04 1.20564E-06     1.000  1
  3    2.000  180.000  272.018 7.48100E+02 3.30000E-04 1.09038E-06     1.000  1
...etc
 47  105.000  180.000  221.063 1.11603E-04 9.05438E-05 2.37295E-13     5.000  1
 48  110.000  180.000  265.192 5.65723E-05 5.18274E-05 6.05628E-14     5.000  1
 49  115.000  180.000  327.066 3.29121E-05 3.78736E-05 2.20778E-14     5.000  1
                                                Total: 1.17960E-05   120.000
[eof]