[en] The 1996 NOVA atmospheric boundary layer data from North Carolina are used in 30 minute's averages for five days. Because of missing data of friction velocity (u) and sensible heat flux (H), it is urgent to calculate (u*)and (H) using the equations of logarithmic wind speed and net radiation (Briggs [7]), which are considered in this work. It is found that the correlation between the predicted and observed values of (u*) and (H) is 0.88 and 0.86 respectively. A comparison is made of the Monin-Obukhov length scale (L) estimated using Richardson number (R_i) and bulk Richardson number (Ri_b) with L-value computed using formula of (L), it is found that the agreement between the predicted and observed values of (L) is better in the case (L)is estimated from the bulk Richardson number (Ri_b), rather than from the gradient Richarson number(R_j)