The GADS ftp distribution:

Version

• Changes against former versions.
  
• List of desirable improvements.

Download

The GADS data set is available on the anonymous ftp server of our computer center.

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Installation

Installation should be easy. Just untar the archive in an empty directory:

> gzip -d gads22a.tar.gz
> tar -xvf gads22a.tar

This will create 3 subdirectories and copy all files in their appropriate places. The tar and gzip programs are also available for DOS (e.g. here). You will need about 3.5 MB of disk space.

If you did already install the software package OPAC (Optical Properties of Aerosols and Clouds), you should install GADS in the same directory, since GADS and OPAC use the same set of optical data of aerosol components, which are stored in the subdirectory optdat.

To use the program gads.f, you must compile it first:

> f77 gads.f -o gads

should be sufficient. You can now start the program by typing gads. The program has been tested to compile and run under Linux, SunOS, HPUnix, Dec Ultrix, and DOS. Please tell us about any difficulties.

The following files belong to GADS:

• The global distribution of aerosol microphysical properties is stored in the subdirectory glodat in the files:
  
  
  • winter.dat: valid for the period September to February.
    
  • summer.dat: valid for the period March to August.
    

  These files have nearly the same format as the tables published in d'Almeida et al. (1991). They contain the number densities of the aerosol components and a number, indicating the type of height profile used for calculating the optical depth, all on a 5x5 degree grid. They also contain still several columns with information about aerosol types and average relative humidity, which, however, are obsolete and no longer used in the present version. There is no description of the contents included in the current version of the files, but may be found here.
  

• The optical properties of the 10 aerosol components, for 8 relative humidities and 61 wavelengths are stored in the subdirectory optdat. Each aerosol component has up to 8 files (for the humidity classes), each containing data for all 61 wavelengths. The filename consists of a 4 letter approximation for the aerosol component, combined with the relative humidity, for which the optical properties have been calculated:
  
  
  

  IC	~	0%	50%	70%	80%	90%	95%	98%	99%
  1	insoluble	inso00	-	-	-	-	-	-	-
  2	watersoluble	waso00	waso50	waso70	waso80	waso90	waso95	waso98	waso99
  3	soot	soot00	-	-	-	-	-	-	-
  4	sea salt(acc. mode)	ssam00	ssam50	ssam70	ssam80	ssam90	ssam95	ssam98	ssam99
  5	sea salt(coa. mode)	sscm00	sscm50	sscm70	sscm80	sscm90	sscm95	sscm98	sscm99
  6	mineral (nuc. mode)	minm00	-	-	-	-	-	-	-
  7	mineral (acc. mode)	miam00	-	-	-	-	-	-	-
  8	mineral (coa. mode)	micm00	-	-	-	-	-	-	-
  9	mineral (transported))	mitr00	-	-	-	-	-	-	-
  10	sulfate droplets	suso00	suso50	suso70	suso80	suso90	suso95	suso98	suso99

  
  
  
• The program gads.f, which is used to calculate the global distributions of optical or microphysical properties from the above described data files, is located in the subdirectory gads22.
  
• Several other files are needed by gads.f. They are also stored in the subdirectory gads22:
  
  
  • profiles.dat: contains 7 height profiles for calculations of the optical depth.
    
  • extback.dat: contains wavelength dependent extinction coefficients of the background aerosols, i.e. the free tropospheric aerosol and the stratospheric aerosol. These values are also needed for calculating optical depths.

Using the program gads:

With help of the program gads, you can produce files with global distributions of some of the microphysical properties of aerosol components, and of the most relevant optical properties of the total aerosol at the gridpoints. These files have the same format with respect to the global distribution, as the files winter.dat and summer.dat.

The program asks for any input it needs interactively. You will have to take the following decisions on your way through the program. The letters in parentheses indicate, what to answer, according to your decision:

• (w)inter or (s)ummer?
  
  
• do you want to get (m)icrophysical or (o)ptical data?
  
  in case of microphysical data:
  
  
  • choose parameter to extract from database:
    
    

    NUMBER DENSITIES:	MASS:
    .	.
    (1) total number density	.
    (2) insoluble	(13) insoluble
    (3) watersoluble	(14) watersoluble
    (4) soot	(15) soot
    (5) sea salt (acc)	(16) sea salt (acc)
    (6) sea salt (coa)	(17) sea salt (coa)
    (7) mineral (nuc)	(18) mineral (nuc)
    (8) mineral (acc)	(19) mineral (acc)
    (9) mineral (coa)	(20) mineral (coa)
    (10) min.tra.	(21) min.tra. (neu)
    (11) sulfate	(22) sulfate
    .	.
    (12) Aerosol Types	(23) Profil Typ

    
    
    please select number (0=END):
    
    This part of the program contains an endless loop over this table, which can be interrupted by entering 0. Thus you can produce several output files during one program run, which will all be named automatically according to their contents.
    

  in case of optical data:
  

  • please select wavelength:
    
    

    ( 1) 0.25 um	(26) 4.50 um	(51) 17.20 um
    ( 2) 0.30 um	(27) 5.00 um	(52) 18.00 um
    ( 3) 0.35 um	(28) 5.50 um	(53) 18.50 um
    ( 4) 0.40 um	(29) 6.00 um	(54) 20.00 um
    ( 5) 0.45 um	(30) 6.20 um	(55) 21.30 um
    ( 6) 0.50 um	(31) 6.50 um	(56) 22.50 um
    ( 7) 0.55 um	(32) 7.20 um	(57) 25.00 um
    ( 8) 0.60 um	(33) 7.90 um	(58) 27.90 um
    ( 9) 0.65 um	(34) 8.20 um	(59) 30.00 um
    (10) 0.70 um	(35) 8.50 um	(60) 35.00 um
    (11) 0.75 um	(36) 8.70 um	(61) 40.00 um
    (12) 0.80 um	(37) 9.00 um	.
    (13) 0.90 um	(38) 9.20 um	.
    (14) 1.00 um	(39) 9.50 um	.
    (15) 1.25 um	(40) 9.80 um	.
    (16) 1.50 um	(41) 10.00 um	.
    (17) 1.75 um	(42) 10.60 um	.
    (18) 2.00 um	(43) 11.00 um	.
    (19) 2.50 um	(44) 11.50 um	.
    (20) 3.00 um	(45) 12.50 um	.
    (21) 3.20 um	(46) 13.00 um	.
    (22) 3.39 um	(47) 14.00 um	.
    (23) 3.50 um	(48) 14.80 um	.
    (24) 3.75 um	(49) 15.00 um	.
    (25) 4.00 um	(50) 16.40 um	.

    
    
    
  • please select rel. humidity:
    
    

    ( 1) 0%
    ( 2) 50%
    ( 3) 70%
    ( 4) 80%
    ( 5) 90%
    ( 6) 95%
    ( 7) 98%
    ( 8) 99%

    
    
  
  in this case, each program run creates one result file, named aererg, which contains the following optical properties at one wavelength and one relative humidity:
  
  
  • ext.coef: extinction coefficient [1/km]
  • sca.coef: scattering coefficient [1/km]
  • abs.coef: absorption coefficient [1/km]
  • sisc.alb: single scattering albedo
  • asym.par: asymmetry parameter
  • op.depth: optical depth
  • li.ratio: lidar ratio [sr]
    
    

  At those gridpoints, where a mineral transported aerosol layer is considered, the optical properties of this layer are given in a seperate line, except for the optical depth, which is given in the first line for the whole atmosphere. The number of layers considered (1 or 2) is given in the 3rd column.