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Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temperature in the oasis and Gobi Desert meet phi (theta) (z/I >) = alpha (theta) (-z/I >)(-1/3) while normalization variances of both humidity and CO2 in the oasis meet phi (s) (z/I >) = alpha (s) (1-alpha (s) z/I >)(-1/3); the normalization variance of temperature in the oasis is large due to disturbance by advection, whereas variance of CO2 in the Gobi Desert has certain degree of deviation relative to Monin-Obukhov (M-O) scaling, and humidity variance completely deviates from variance M-O scaling. The above result indicates that under the condition of advection, humidity variance meets the relation sigma (sm) (2) = D (2) sigma (sA) (2) + sigma (sB) (2) and it is determined by relative magnitude of scalar variance of advection transport. Our study reveals that, if the scalar variance of humidity or CO2 transported by advection is much larger than local scalar variance, observation value of scalar variance will deviate from M-O scaling; when scalar variance of advection transport is close to or less than local scalar variance, the observation value of scalar variance approximately meets M-O scaling.