RTV File Structure

25SEP22 - Original
Contents

Overview

MORSE generates two types of profile output: retrieval (.rtv) and orbital (.orb) files. Both conform to the same file structure.

The retrieval file contains the retrieved state vector and associated uncertainties, while the orbital file contains extended profiles of the retrieved parameters covering the full MORSE forward model altitude range, which should be used for passing MORSE outputs into subsequent runs of MORSE.

The file consists of a record-structured header section, then sets of profiles for each 'Pixel', ie geographical location (in this case, just a single location representing a single occultation).

Example: hsdi.rtv, which can be read with IDL function read_rtv.pro

File Structure

File Structure Overview
File_Header_Section defines NPix, NSet, NPrf
For iPix = 1, NPix 1 expected for Cubemap
      Pixel_Header_Section
      For iSet = 1, NSet 1 expected for Cubemap
            Set_Header_Record
            For iPrf = 1, NPrf
                  Profile_Data

File Header Section
!CMNT Comment records starting with '!'
Format_ID File format version
View_ID 2=limb transmittance spectra
Instrument Satellite Instrument, Satellite
Nom_Date Julian_Day Nominal date, day# since 1Jan2000
Orbit Time_Start   Time_End Orbit#, Start HHMMSS, End HHMMSS
NPix NSet No. Pixels, No. Sets/pixel
NLev NPrf No. Levels, No. Profiles
*GRD Profile vertical grid
GRD(1), GRD(2), ... Profile grid levels
... GRD(NLev)
For iPrf = 1, NPrf
    PRF_ID(iPrf) NLevP(iPrf) Profile ID and No.levels used
    If NLevP(iPrf) < NLev If not full profile ...
        FLG(1,iPrf), FLG(2,iPrf), ... 1=used level, 0=not used
        ... FLG(NLev,iPrf),
*END End-of-Header marker
Pixel Header Section
iPix Pixel#
!CMNT Text headers for next record
YMD       HMS       msc       Lat       Lon       LST       SZA
Set Header Record
!CMNT Comment record, eg '! Final Result'
Profile Data
*PRF_ID Profile ID (single record)
PRF(1) PRF(2) ... Profile values, over as many records as required
... PRF(NLevP)

Data Dictionary

Field Type Description Units Range
!CMNT String*80 Comment record first character is '!'
*END String(4) Marker for end of file header section '*END'
Format_ID Float File format identifier [1] 2.0 expected
FLG Boolean(NLev) Flags 1=used , 0=skipped for profile [2] 1 or 0
*GRD String Profile vertical grid type '*HGT' expected
GRD Float(NLev) Profile grid levels km (if *GRD = '*HGT')
HMS Long Time of measurement, UT hhmmss Time_Start : Time_End
Instrument String*10 Instrument name eg 'HIROS     '
iPix Integer Pixel/location number within file 1 : NPix (1 expected)
Julian_Day Long Nom_Date as Day# since 1 Jan 2000 (=0) eg 8401 (1st Jan 2023)
Lat Float Nominal latitude of profile deg N −90 : +90
Lon Float Nominal longitude of profile deg E −180 : +180
LST Float Nominal Local Solar Time of profile (12=noon) hr 0.0 (not set)
msc Long Time of measurement, UT milliseconds 0 : 86 400 000
NLev Integer Max No. levels in profiles > 0
NLevP Integer(NPrf) No. levels in each profile [2] 0 : NLev
Nom_Date Long Nominal observation date yyyymmdd eg 20230101
NPix Integer No. Profile locations in the file 1 expected
NPrf Integer No. different profiles per pixel > 0
NSet Integer No. Sets of profiles per location [3] 1 expected
Orbit Long Satellite orbit number since launch > 0
PRF Float(NLevP) Profile data [4]
PRF_ID String(NPrf) Parameter represented by each profile [5] eg 'CH4'
Satellite String*10 Satellite name eg 'Cubemap 1 '
SZA Float Solar Zenith Angle of profile (0=sun overhead) deg 0.0 (not set)
Time_End Long End of measurement UT hhmmss eg 120320
Time_Start Long Start of measurement UT hhmmss eg 120000
View_ID Integer Viewing Geometry identifier [6] 2 expected
YMD Long Date of measurement yyyymmdd Nom_Date−1 : Nom_Date+1

Notes

  1. This is always the first non-comment field in the file, and is to allow any reading program to handle multiple versions of the file format.

  2. If the retrieved product is not represented on every GRD level (ie NLevP < NLev) then FLG provides a series of flags marking which GRD levels are used.

  3. The format allows for intermediate results to be included within the same file, eg A Prori profiles and/or outputs after measurements are incorporated from each microwindow/filter.

  4. Retrieved profiles of geophysical quantities, and also associated diagnostic products (some of which, eg information content, may be scalars). Units and range depend on the parameter represented.

  5. PRF_ID appears, without an asterisk, in the File Header Section and, with a preceding asterisk, in the Profile Data (the asterisk denotes a header for subsequent data).

  6. View_ID: MORSE currently handles three different viewing geometries: Limb radiance (1), Limb transmittance (2) or Nadir Radiance (3). For Cubemap, geometry 2 applies.

Document Changes

25SEP22 Original