AstroCalc4R : software to calculate solar zenith angle; time at sunrise, local noon, and sunset; and photosynthetically available radiation based on date, time, and location

"AstroCalc4R for Windows and Linux can be used to study diel and seasonal patterns in biological organisms and ecosystems due to illumination. The algorithms require more time to understand and program than would be available to most biological researchers. In contrast to the algorithms, the results are understandable and links to marine and terrestrial ecosystems are obvious to biologists. Diel variation in solar energy affects the energy budgets of ecosystems (Link et al. 2006) and behavior of a wide range of organisms including zooplankton, fish, marine birds, reptiles and mammals; and aquatic and terrestrial organisms (e.g. Hjellvik et al. 2001). The solar zenith angle; time at sunrise, local noon and sunset; and photosynthetically available radiation (PAR) are the most important variables for biology that are calculated by AstroCalc4R. PAR is the amount of photosynthetically available radiation (usually wavelengths of 400-700 nm) at the surface of the earth or ocean based on the solar zenith angle under average atmospheric conditions"--Summary. by Larry Jacobson, Alan Seaver, and Jiashen Tang. "August 2011." Includes bibliographical references (page 5) and endnotes. Jacobson L, Seaver A, Tang J. 2011. AstroCalc4R: software to calculate solar zenith angle; time at sunrise, local noon and sunset; and photosynthetically available radiation based on date, time and location. US Dept Commer, Northeast Fish Sci Cent Ref Doc. 11-14; 10 p.