File: ABSTRACT.TXT


                       GCSOLAR Model System Abstract


               Center for Exposure Assessment Modeling (CEAM)
     National Exposure Research Laboratory - Ecosystems Research Division
                  Office of Research and Development (ORD)
               U.S. Environmental Protection Agency (U.S. EPA)
                          960 College Station Road
                         Athens, Georgia 30605-2700

                                706/355-8400



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                                  Summary

GCSOLAR program is a set of routines that computes direct photolysis rates
and half-lives of pollutants in the aquatic environment.  The half-lives are
calculated as a function of season, latitude, time-of-day, depth in water
bodies, and ozone layer thickness.

This program operates in an interactive screen mode to facilitate data and
program command entry by the user.  Input values, with few restrictions, are
format free.  The user controls program flow by entering program execution
commands.  This release (1.10 February 1988 and 1.20 July 1999) of the
GCSOLAR program differs from earlier versions of the program in that it
permits the user to compute photolysis rate constants as a function of
elevation above sea level.  This is implemented with the GCSOLAR ELEVATION
command.  For a more detailed explanation of the model and its functionality,
see the enclosed user manual file (USERMANU.PDF).

For a complete discussion of the chemistry associated with this program,
refer to the publication "Rates of Direct Photolysis in Aquatic Environment",
R. G. Zepp and D. M. Cline, Environmental Science and Technology, 11:4, PP
359-366 (1977).

                                Documentation

The GCSOLAR User's Manual is available as an Adobe(*) Acrobat(*) Portable
Document Format (PDF) file (USERMANU.PDF) within the DOCUMENT sub-directory
if the user chose to install the user's manual from the INSTALGC.EXE program
install menu.  To view, print, and/or navigate a PDF document, a reader
program must be installed on the users computer system.  A free Adobe reader
allows the user to view, navigate, and/or print PDF files across all major
computing platforms.  Acrobat Reader is a free viewing companion to Adobe
Acrobat 3.0 and is available free from the Adobe world wide web (WWW) site at
Uniform Resource Locator (URL) address: http://www.adobe.com.

To ensure that the user can view and/or print a PDF file in its entirety, the
user must down load and install the most recent version/edition of the free
Acrobat Reader.  PDF files can be viewed across multiple platforms (Mac,
Microcomputer, UNIX) using the appropriate reader for that platform.

* Adobe, Acrobat, and Adobe Type Manager are trademarks of Adobe Systems
Incorporated and may be registered in certain jurisdictions.  (C) Copyright
1994 Adobe Systems Incorporated.  All rights reserved.

Refer to file READ.ME in the README sub-directory for further information on
the storage format and hardware and/or software print/view requirement(s) of
the user's manual file.

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