OPAC - Installation Guide

Note: This guideline does not aim to replace the official installation steps provided by the authors of the OPAC software. We therefore not take any warranty of the correct performance of the OPAC software. For any questions about its installation, it is recommended to contact the corresponding OPAC authors.

- The following instructions are directly extracted and adapted from the official OPAC site -

OPAC consists of ASCII files, which contain the optical properties of cloud and aerosol components and of a FORTRAN program, which allows handling the data. The FORTRAN program was tested to compile and run under DOS (Microsoft Fortran 5.0), Linux (GNU f2c converter), DEC Ultrix, HP Unix, and SunOS. The whole package required about 3.5 MB storage capacity.

The software package v3.1 can be downloaded from the OPAC website (http://www.rascin.net/de/opac_package). This consists on the opac31a.tar file containing the Fortran source code and databases.

This section provides basic instructions for downloading and compiling the OPAC v3.1 aerosol database.

Notice that an upgraded version of OPAC (v4.0) is currently available at http://www.rascin.net/de/opac_40. However, it has not been tested for its integration in ALG v1.2 and its coupling with MODTRAN v5.2. In what follows, this section refers to the installation of OPAC v3.1.

Prerequisites for installing OPAC

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In order to install OPAC v3.1, your computer first needs to have the command tools make and tar from the GNUWin32 project. In addition, a Fortran77 compiler should be available in your computer. Omit this if you have previously installed 6SV. Otherwise, follow the steps detailed in 6SV - Installation Guide.

Download the OPAC v3.1 source code from the official OPAC website (http://www.rascin.net/de/opac_package) and the GADS database from its official webpage (http://www.rascin.net/de/gads). Both the source-code and database are compressed in .tar files (opac31a and gasd23b). Move these .tar files to the folder where you want to unzip and compile the code e.g., C:\Program Files (x86)\OPAC.

Installing OPAC

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After downloading the OPAC v3.1 .tar file, open the command window by opening the Start Menu and typing cmd. In the terminal, change the working directory where the two OPAC .tar files have been saved and unzip them:

cd C:\Program Files (x86)\OPAC\
tar -xvf opac31a.tar
tar -xvf gasd23b.tar

Alternatively, you can use instead any suitable unzip tool such as WinRAR. This will unzip the .tar file and create two new sub-directories (opac31 and optdat) corresponding to the source code and the aerosol optical database respectively.

Before compiling the opac.f Fortran77 file, you first need to modify it with a text editor such as Notepad (not Word) depending whether the system is Unix of DOS. For Unix computers, the file should not be edited but for DOS computers, you must comment out lines 505-507 instead of 501-503 since the "\" character is not understood by all compilers. Once done, move to the opac31 directory and compile the opac.f file with your Fortran77 compiler:

cd opac31
g77 opac.f –o opac

If no errors have been produced, and executable file named opac will be created. Test the OPAC executable by simply typing:

opac

OPAC will ask you to introduce the name of the input file, which should be stored in the sub-folder input:

Introduce the default file by typing opac. If OPAC is working correctly, the command window will show a set messages ended with the word READY:

An output file will be generated in the sub-folder results with the same name as the input file and extension .out.