*FLG Section

09JUL25

Type

Mandatory Section#2

Description

A series of 3-letter codes indicating various MORSE options to be 'switched on' (all switched off by default)

Format

Multiple 3-character fields of single type, any order, limited set of values.

Field	Type	Value	Description
FLG	C3	ACC	More stringent default accuracy/convergence criteria[1]
		AHY	Suppress hydrostatic equilibrium[2]
		APR	Include A Priori profiles (as an extra SET) in .rtv files
		CLD	Use cloud detection (see *CLD section)
		COL	Add integrated column amounts in .rtv files
		CTM	Use molecular (eg H2O) continuum data (same as RFM Flag)
		FGD	Use full, as opposed to irregular, grid
		FIX	Assume fixed relative altitudes (eg detector array)
		FMW	Use full microwindow (ie set all masks = TRUE)
		FVZ	Suppress FOV distortion due to refraction
		GEO	Use geometric (ie non-refractive) ray paths
		INF	Include information diagnostics in in .rtv
		LIN	Assume VMR varies linearly with altitude rather than logarithmically
		MIX	Use CO2 line mixing
		MWO	Write outputs after each microwindow in .rtv files
		QAD	Use simple quadratic fit to line wings rather than inverse quadratic (same as RFM)
		RES	Include vertical resolution factor in .rtv files
		RSM	Allow run to resume from last pixel

Notes

1. ACC: Specifically scales the following default settings

   Parameter	Default	ACC flag
   Convergence Criteria (see *CNV)
   MAXITR	10	×10
   CHILIM	1.0	×0.1
   DELCHI	0.1	×0.1

2. AHY: This decouples the pressure and temperature profiles so that these are treated as independent.
   • Limb-sounding: retrieved independently without any consideration of altitude spacing
   • Nadir-sounding: use explicit altitude grid for vertical path integrations
   CLD
   If listed as absorbing gases, this includes the continua associated with H2O, CO2, O2 and N2 (same as with the RFM CTM Flag).

   FGD
   If using an irregular spectral grid, either via the *GRD section or using a MIPAS Microwindow Database File (MDBFIL), this switches it off and uses a full, regular grid instead.

   FIX
   The default is to assume that the individual measurements contributing to a limb scan have some relative pointing uncertainty, so that the height/pressure at each tangent point is an independent unknown. With this flag, it is assumed that the relative heights are fixed, and so the hydrostatic equation can be used to reduce the problem to the tangent height/pressure at a single reference level.

   FMW
   For use with (MIPAS) microwindow database files (.mdb files). The database file contains the set of spectral masks which are applied by default. The effect of this flag is to remove these masks and use every point within the microwindow to construct the measurement vector.

   FVZ
   Same as RFM FVZ Flag. However, since MORSE only processes one limb-viewing direction at a time there is no efficiency benefit in using this flag.

   GEO
   Same as RFM GEO Flag. Sets refractive index to 1.

   INF
   Add 3 (scalar) diagnostics for each retrieved species to .rtv files

   CSQ

   Average χ² of deviation of retrieval from A Priori

   DFS

   Degrees of Freedom for Signal

   INF

   Information content

   LIN
   Same as RFM LIN Flag.

   MIX
   Same as RFM MIX Flag.