The aerodynamic gradient method was applied to estimate dry deposition flux of SO2
over dry deciduous forest in Nakorn
Ratchasima province, Thailand. The meteorological parameters and concentrations of SO2
were measured in real time
for one year on the experimental tower at 36 and 27 m high. The flux observed in the wet season were found two times
higher than the value observed in the dry seasons, i.e. 20±7.58 and 10±11.05 ng m-2 s-1, respectively. The leaf area
index and the ambient humidity were believed to assert the rate of SO2
deposition. The average friction velocities were
estimated to be 0.26±0.02 and 0.48±0.06 m s–
¹, for the dry and the wet season, respectively. The friction velocity was
very much depended on the surface roughness of the forest canopy. The Vd
of SO2
evaluated by the aerodynamic gradient
was compared with Vd calculated by the resistance model. It was found that the observed Vd
was in close proximity with
the model prediction in daytime in all conditions, i.e. wet, dry and annual average. The annual average Vd
determined
by the Aerodynamic gradient was 0.43±0.06 cm s-1.