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Environmental Modeling Community of Practice



GCSolar is desktop program 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 has a graphical user interface (GUI) to facilitate user interaction.  The user can enter input values, import and export water and pollutant of concern absorption coefficients, and view results as graphs. This release (1.0 July 2018) of the GCSolar program differs from earlier versions of the program in that it is written in C# whereas the previous versions were written in FORTRAN.  This version also permits the user to interact with the application using graphical user interface.

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).

Current Version: 1.0
Release Date: July 2018
Development Status: General Release
Development Information: Release Notes - changes and known deficiencies
Operating System: 64-bit Windows 10
Development Language: .NET version 4.5
Intended Audience: Environmental Scientist/Biologist
Key Words: solar, photolysis, half-life, pollutant, aquatic, ozone
Related Web Sites: None Available
Text Files (ASCII Format)
File Name File Description
GCSolar Abstract(1 pg, 1 K) Summary of functions, theory, and applicability.
Download Files
File Type /
File Name /
Format /
File Description
Install /
GCSolar Install Executable(3 pp, 2 MB) /
Self-extracting Executable /
Setup file for version 1.0 of the GCSOLAR system.
Document /
GCSolar User's Manual GCSOLAR User's Manual