uvspec is part of the libRadtran package which is available at
http://www.libradtran.org

To unpack libRadtran issue the following commands on a unix system:

    gzip -d libRadtran-latest-version-number.tar.gz
    tar -xvf libRadtran-latest-version-number.tar

Next 

    cd libRadtran-latest-version-number

and follow the instructions in the README and INSTALL files.

Documentation is found in the doc directory as postscript files 
(libRadtran.ps).

uvspec is found in the tools directory. It uses both C and Fortran
code. Hence, to compile and link uvspec a Fortran compiler that
is comaptible with C is needed. The configure script will find out
whether your system's Fortran and C compilers are compatible.

libRadtran is being developed on a Pentium powered system running
the freely available linux operating system (www.linux.org).