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3.4.3 GOMOS products toolbox

The GOMOS products toolbox allows to visualise and edit the GOMOS products. It is relevant to all GOMOS products: auxiliary products, Level1b and Level2 products including the meteo products. In order to extract data from the GOMOS products, a specific data dictionary must be available in the working environment of the user. The toolbox has been developed for Sun Unix platforms, system Solaris 2.6.

We provide here only the main guidelines for the use of the toolbox. The User Manual of the GOMOS Products Toolbox is available at:
 http://www.acri-st.fr/tools/gomos/gomos_toolbox_user_is2r0.pdf
(issue 2.0, 2003). More information is available on request at: gb@cri-st.fr (Gilbert Barrot, ACRI-ST company).

The toolbox contains a set of several programs, which main functionalities are to extract data from a product for plotting, and to modify a field in a product.

gomtab          extraction of data from a GOMOS Level0 products

display_pr      extraction of data from a GOMOS product (except a Level0 product)

info_pr           returns the number of elements of a specified field of a product

export_pr                extraction of data from a GOMOS product; the output format is compatible with the input format of modify_pr

modify_pr               allows to modify a product; reads an ASCII file generated by export_pr and stores the data in a product.

                        The input data must be fully compatible with the product (same size of the field)

diff_pr            comparison of two products

header_pr      writing of the header of a product on the standard output

extract_pr      extraction of the values of a variable written in a file generated by display_pr or export_pr.

More details on the use of the programs are given in Table 3.8 .

Program name

Short description and use
gomtab Extract the data from a GOMOS level 0 product

 


gomtab prd_name [nrec]
prd_name is the level 0 product filename
nrec is the occultation measurement number
<output on the standard output device>
Note: today only level 0 with only one occultation can be processed with gomtab.
display_pr Extract the data from a product

 
display_pr prd_type prd_name [code]
prd_type is the type of the product
prd_name is the product filename
code is the GOPR data dictionary code (like 6403).
If not specified, then all the product is displayed
<output on the standard output device>
info_pr Returns the size of a product field
  info_pr prd_type prd_name code
prd_type is the type of the product
prd_name is the product filename
code is the GOPR data dictionary code (like 6403).
<output on the standard output device>
export_pr Similar to display_pr except that the output format is compatible with the input format of modify_pr
  export_pr prd_type prd_name ascii_name [code]
prd_type is the type of the product
prd_name is the product filename
ascii_name is the name of the output file (ASCII format)
code is the GOPR data dictionary code (like 6403).
If not specified, then all the product is exported
<output in the ascii_name file>
modify_pr Allows to modify a product. Read an ASCII file generated by export_pr and store the data in a  product. Note that the input data must be fully compatible with the product (same size of the data)
  modify_pr ascii_name prd_name prd_type
ascii_name is the name of the input file (ASCII format)
prd_name is the product filename
prd_type is the type of the product
<no output - prd_name file is modified>
diff_pr Comparison of two products
  diff_pr prd_type prd_name1 prd_name2
prd_type is the type of the product
prd_name1 is the first product filename
prd_name2 is the second product filename
<output on the standard output device>
header_pr Write the header of a product on the standard output
  header_pr prd_name prd_type
prd_name is the product filename
prd_type is the type of the product
<output on the standard output device>
extract_pr Extract the values of a variable written in a file generated by display_pr or export_pr
  extract_pr file code nval INT|REAL|MJD MDS|GADS [f0] [k0]
file is a file created by a display_pr or export_pr command
code is the GOPR data dictionary code (like 6403)
nval is number of values to be read by record
INT|REAL|R8|MJD specifies if the data type is integer, real or date
MDS|GADS is the type of the record to be read (if this is a GADS,
  only one value must be read (and there is no additional value
  after the variable description in the input file).
f0: if the type is a MDS, and if f0 is specified, then extract
  only the record number f0 (this is useful to extract only one
  MDS record like for the transmission). All MDSR by default
  when f0 is not specified or set to -1
k0: only element k0 of the extracted vector is displayed. All vector
  is displayed if k0 is not specified.
<output on the standard output device>

Table 3.8: Specificities and instructions for use of the GOMOS toolbox programs.

In the description of the product content (see section 2.2.3 of this document) and in the IODD reference document, the unit and the possible conversion factor used to store the Data Sets are detailed. It is important to note that the GOMOS products toolbox, similarly to BEAT tools, handle those conversion factors and thus return "decoded" data set values. For instance, all standard deviation data set records are stored in (1.e-1)% in the products. The data values returned by the toolbox programs are given in %.

Two examples of use are presented in Table 3.9 and Table 3.10 .

Extraction of transmission values and nominal wavelength assignment from a Level1b product.
The GOPR data dictionary codes for the transmission and the wavelength assignment are 1602 and 1301 respectively.

sh> display_pr 1 GOM_TRA_1PNACR20030121_080958_000000462013_00106_04669_0001.N1 1301 1602 > zzz.dat

sh> NVAL=`info_pr 1 GOM_TRA_1PNACR20030121_080958_000000462013_00106_04669_0001.N1 1301`

NVAL contains the number of elements of field 1301

sh> extract_pr zzz.dat 1301 $NVAL REAL GADS > wl.dat

wl.dat contains the nominal wavelengths extracted from zzz.dat file

sh> extract_pr zzz.dat 1602 $NVAL REAL MDS 50 > trans.dat

trans.dat contains the transmission of the 51-th measurement extracted from zzz.dat file

sh> paste wl.dat trans.dat > plot.dat

the transmission data and the wavelength data are merged in a single file named plot.dat

sh > xmgrace plot.dat

graphic

Table 3.9: Example of use of the GOMOS toolbox programs: extraction of the transmission for plotting versus nominal wavelength.

Extraction of the vertical profile of O3 local density  from a Level2 product.
The GOPR data dictionary codes for the O3 local density and the tangent point altitude are 3607 and 3202 respectively.

sh> display_pr 3 GOM_NL__2PNACR20030121_080958_000000462013_00106_04669_0001.N1 3202 3607 > zzz.dat

sh> NVAL=`info_pr 3 GOM_NL__2PNACR20030121_080958_000000462013_00106_04669_0001.N1 3202`

NVAL contains the number of elements of field 3202

sh> extract_pr zzz.dat 3607 $NVAL REAL MDS > alt.dat

alt.dat contains the tangent point altitude extracted from zzz.dat file

sh> extract_pr zzz.dat 3202 $NVAL REAL MDS > o3.dat

o3.dat contains the O3 local density values extracted from zzz.dat file

sh> paste o3.dat alt.dat > plot.dat

the O3 local density data and the tangent point altitude data are merged in a single file named plot.dat

sh > xmgrace plot.dat

graphic

Table 3.10: Example of use of the GOMOS toolbox programs: extraction of the O3 local density for plotting versus the vertical altitude.