Observations of three stratospheric species (N2O, CH4, and NOy) are examined for their suitability as mixing tracers in the inner Arctic vortex region between late February and mid-March, 2000. NOy is highly inhomogeneous on isentropic surfaces and has little systematic vertical gradient between the 420 and 470 K potential temperature surfaces due to severe and extensive denitrification. Probability distribution functions of NOy calculated from in situ measurements do not show systematic and significant change as a function of time, indicating that mixing was too slow to strongly affect O3 destruction during the period. We propose that the NOy inhomogeneity is useful for diagnosing small-scale, irreversible mixing rates during the measurement period. A simple kinematic model is used to show that the NOy standard deviation on an isentropic level in the vortex has desirable properties for quantifying these rates. A practical method for deriving mixing rates for chemistry and transport models has been proposed for future studies.