*MIC Section

24MAR25

Type

Mandatory Section#6

Description

List of microwindows or spectral filters to be used, and absorbing species to be considered (in addition to retrieved species, which are assumed to be absorbers in every microwindow)

The format is different according to whether limb or nadir-viewing geometry is selected, and if spectral filters are used rather than microwindows.

The section can either contain the microwindow information directly, or the names of files with the same data structure, or a combination of the two.

MORSE processes the microwindows sequentially in the order in which they appear in this section. In theory the end result should not be sensitive to the order in which microwindows are used but in practice there are always small differences due to convergence, etc.

Structure

Different structures for Nadir and Limb-Viewing, or fields of names of files containing text in the appropriate format

Filenames (Nadir or Limb)
MICFIL	Name of Microwindow File
Nadir-Viewing
MICLAB WNOMIN WNOMAX NABS [NCHN]	Rec#1: Microwindow Header
ABS(1) ABS(2) ... ABS(NABS)	Rec#2: Microwindow absorbers
[CHN(1) CHN(2) ...	Rec#3+: Microwindow channels (if NCHN present)
... CHN(NCHN) ]
Limb-Viewing
[ISEQ] MICLAB WNOMIN WNOMAX ALTMIN ALTMAX [IDXABS(1) IDXABS(2) ... IDXABS(NABS)]	Single record
Repeat for further microwindows
MIPAS Microwindow Database File(s)
MDBFIL=filename	Name of MDB file

Fields

Field	Type	Description	Units	Range
MICFIL	Cn	Name of a Microwindow file		eg miclist.txt
MICLAB	C8	Microwindow Label		eg NH3_0001
WNOMIN	D	Microwindow Lower Boundary	cm-1	0 < : ≤ WNOMAX
WNOMAX	D	Microwindow Upper Boundary	cm-1	≥ WNOMIN
Nadir-Viewing only
NABS	I	No. of absorbing species		≥ 1
NCHN	I	(Optional) No. channels/points to use within microwindow		1 : NPt
ABS(NABS)	I	Names of absorbers		eg 'CO2' or 'co2'
CHN(NCHN)	I	(If NCHN set) Channel indices within microwindow		1 : NPt
Limb-Viewing only
ISEQ	I	(Optional) Microwindow number in sequence (ignored)		e.g., 1, 2, ...
ALTMIN	R	Minimum tangent altitude	km	< ALTMAX
ALTMAX	R	Maximum tangent altitude	km	> ALTMIN
IDXABS(:)	I	HITRAN/RFM indices of absorbers		1 : 184 (see List)

Type: I=Integer; D=Double Precision; Cn=character string, length n.

Notes

1. For Nadir-viewing, there is a minimum of two records per microwindow, with 3rd and subsequent records determined by the presence and value of NCHN. For limb-viewing there is a single record per microwindow, although further information may be provided (for MIPAS) via Microwindow Database files (*MDB section)
2. Absorbing species ABS can be upper or lower case, up to 7-characters, corresponding any of the list of RFM molecules
3. All retrieved species are considered as absorbers for all microwindows whether they are explicitly listed here or not.
4. Microwindow channels CHN(j) are the indices of spectral points at the L1B resolution within the microwindow, so a channel #1 corresponds to WNOL and #NCHN corresponds to WNOU

Format - Limb-viewing

Sets of 1 or more Records up to C200, one record per microwindow

Field	Type	Description	Range
ISEQ	C4	Microwindow sequence number (not used)	eg ' 1 '
LAB	C8	Microwindow Label	eg PT__0001
WNOL	D	MW Lower Wavenumber Boundary [cm-1]	eg 686.400
WNOU	D	MW Upper Wavenumber Boundary [cm-1]	eg 689.400
ALTL	R	MW Lower Tangent Altitude [km]	eg 30
ALTU	R	MW Upper Tangent Altitude [km]	eg 68
ABS(i)	I	RFM/HITRAN Index of absorber#i (Optional)	eg 2 (=CO2)

Or, for MIPAS, PARAM=VALUE record(s) containing the name of Microwindow Database file(s)

MDBFIL=MDBFIL

Field	Type	Description	Range
MDBFIL=MDBFIL	C*	(Optional) name of microwindow database file (MW*DAT)	eg MW_PT__040.DAT

Notes for Limb-Viewing

1. For MIPAS, the microwindow list normally only identifies the microwindow to be used (combination of code and wavenumber boundaries) and the applied tangent height range, with other information coming from the Microwindow Database file. However it is also possible to use the microwindow list to fully specify the microwindow, although without any spectral masks (which can only be specified via the MDBFIL)
2. The first 4 characters of a non-comment record normally contain the number ISEQ (which isn't actually used), the following 8 characters are the label LAB, after that fields are read free-format.
3. The C8 microwindow labels and wavenumber boundaries in the MWLFIL files must match those in the MDBFIL database file in order to identify a matching microwindow
4. If any absorber indices are included in the MWLFIL file these replace all the absorbers in the database file — a useful way of reducing the cpu time/array space by reducing the number of absorbers considered

Examples

Nadir-viewing, direct entry of microwindow information in driver table

*MIC
 NH3_0001 930 940 4 5     ! use 930-940cm-1 range, 4 absorbers, 5 channels
  nh3 co2 h2o o3
  930.75, 931.0, 931.25, 931.5 931.75

Limb-viewing, indirect entry giving names of files holding microwindow information

*MIC
  pt_016.lst  ! pT microwindows
  MDBFIL=MW_PT__510.DAT ! pT FR mode database