Urban Cooling - ccpark formula error?

When I apply basically the ccpark formula, I obtain values greater than 1, whereas they should be less than 1 (because HM is below 1).

There are no literary references for the ccpark formula so I don’t know how to verify its accuracy.
It seems that there is a missing term in the equation that weights all the values obtained with the sum calculation.

Can you help me with this?
Thank you