A Comparison of Different Methods for Measuring the Canopy Light Regime

Abstract

The results of measuring the radiation penetration coefficients within a young pine stand with different types of sensors are compared under clear and overcast sky conditions. The results are compared to the estimates of diffuse and direct solar radiation penetration coefficients calculated from fish-eye photographs made in the same stand. Agreement between the calculated and measured penetration coefficients is quite good for an overcast situation. In sunshine the correlation between the hourly totals of radiation measured and estimated from fish-eye photographs is considerably less than under overcast conditions.