The terrain-induced flows often result in a complicated situation in measurements of trace gas exchanges between vegetation and atmosphere. The stability analysis on the terrain-induced canopy flows is the key to understanding the introduction of pollutants into the atmosphere and the transfer of water from soil and vegetation to the atmosphere.  An analytical criterion of instability of the terrain-induced canopy flows is derived from the simplified thermal-hydro-mechanical equations by nonlinear dynamics approach. The analytical stability criterion is determined from the terrain slope, environmental lapse rate, drag coefficient, and leaf area density of vegetation. The stability of the terrain-induced canopy flows and an oscillation solution are predicted based on the instability-criterion. These predictions are tested against the numerical simulations by the computational fluid dynamics (CFD) approach based on thermal-hydro-mechanical equations.

 

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