Table 1: Error statistics of the training data sets.

Regression equationData points Correlation coefficientsRoot mean square error (mm/h)

Nonlinear equation using SI (3) 5764 0.762 2.061
Nonlinear equation using PCT (4) 5764 0.786 1.952
Nonlinear equation using SI and PCT (5)5764 0.842 1.764