L2 File Structure

07DEC22 Ongoing...
Contents

Overview

Level 2 (L2) files are netCDF format files containing retrieved quantities of geophysical parameters. Within the Cubemap End-to-End (E2E) simulator these are the individual MORSE L2 .rtv output files converted to netCDF format.

Each file contains the measurements from a single occultation event and a single run of MORSE.

Example: l2_hiros_pt.nc, which can be read with the IDL function read_l2.pro

The file was written with IDL procedure make_l2.pro

File Contents

Global Attributes
Name Type Value
Title String eg [1] ' 26SEP22 HIROS pT + H2O retrieval '
Created String eg [2] 'Wed Oct 12 15:45:22 2022'
Source String eg [3] 'Created using make_l2.pro v12OCT22'
Dimensions
Name Size Definition
NHgt eg 26 Number of altitude levels in profiles [4]
Variables
Name Type Definition Units Range
Satellite String Satellite ID [5] eg 'Cubemap 1'
Instrument String Instrument ID [5] eg 'HIROS'
Orbit Long Orbit number [5] > 0
Sunrise Byte 1=Sunrise, 0=Sunset [5] 0 or 1
Julian_Day Long Day since 1st Jan 2000 (=Day 0) [5] > 0
YMD Long Year, Month, Day [6] yyyymmdd eg '20210922'
HMS Long Hours, Minutes, Seconds (UT) [6] hhmmss eg ' 11813'
Lat Float Latitude of retrieved profiles [6] deg N −90 : +90
Lon Float Longitude of retrieved profiles [6] deg E −180 : +180
Hgt Float(NHgt) Retrieved profile altitude levels km 0 – 120 expected
PRFi Float(NHgt) Retrieved Profile, species i [7]
PRFi_SD Float(NHgt) Std Dev Profile, species i [7]
PRFi_RES Float(NHgt) Vertical Resln Profile, species i
PRFi_DFS Float Degrees of Freedom for Signal, species i ≥0
PRFi_Inf Float Information Content, species i bits ≥0

Notes

  1. Title is from the contents of the *HDR section in the MORSE driver file
  2. Created refers to the creation time of the L2 netCDF file
  3. Source refers to the IDL program used to create the netCDF file
  4. NHgt refers to the maximum number of altitude levels for any profile. Some species may be retrieved on a subset of the full height grid in which case the netCDF _FillValue (currently -999.0) will be present at the non-retrieved levels.
  5. Satellite, Instrument, Orbit, Sunrise and Julian_Day: These values originate in the HSDI L1B and HIROS L1B files, transferred via the header sections of the L1C and RTV files.
  6. YMD, HMS, Lat and Lon: the time/location associated with the profiles in the L2 product is established by MORSE from the observation time and boresight tangent point nearest the mid-point (NSwp/2) of the data in the L1C file.
  7. Units depend on retrieved product and can be found under the netCDF 'Units' attribute. These are expected to be
    TEM Temperature K PRE Pressure hPa REFPRE Reference Pressure hPa POI Pointing Adjustment km AEROSOL Aerosol extinction km-1 eg CH4 (eg CH4) Volume Mixing Ratio ppmv
  8. Isotopic species (eg HDO) VMRs have to be multiplied by the HITRAN abundance to obtain the actual concentration.

Document Changes

07DEC22 Ongoing ...