Reasons for the breakdown of Monin-Obukhov similarity theory above rough surfaces

Since Thome (1971) it is known that abouve rough surfaces gradients are

smaller than predicted by Monin-Obkhov similarity theory (MO-theory). In 1989 Raupach

proposed with the localized near field theory (LNF) a lagrangian approach to model

source distributions in plant canopies. This theory can be used to derive a

general formulation for profiles within and above plant canopies. Comparing

such profiles with profiles predicted by MO-theory gives insight into the

mechanisms leading to the deviation from MO-theory. These are mainly the

enhacement of turbulence which reduces gradients and the near field effects

in turbulence which enhance gradients.