CBM code

This app allows to compute the daylength in three situations, namely 1)giving one latitude (degrees) and one date (year,month,day); or 2) one latitude and more days (tipically starting and ending month) [e.g 44.833, 2014, 4, 9; northern latitude, year, april, september]; or 3) more latitudes (tipically an integer range of latitudes, e.g. 15, 65, and a step (degrees), e.g. 2),year, month, day.
cbm also allows to select a so-called daylength coefficient, p.
It uses the CBM model (a modification of Schoolfied, 1982 model), allowing full range latitudes and different definitions of daylength and twilight.

The code derives from:
William C. Forsythe, Edward J. Rykiel Jr., Randal S. Stahl, Hsin-i Wu, Robert M. Schoolfield: A model comparison for daylength as a function of latitude and day of year, Ecological Modelling, 80, 87-95, 1995
and is available here.

Page written: 27 October 2014.                   Last Updated: