SPATIOTEMPORAL DYNAMICS OF THE VARIANCE OF THE WIND VELOCITY FROM MINI-SODAR MEASUREMENTS

摘要

Statistical trends of the spatiotemporal dynamics of the variance of the three wind velocity components in the atmospheric boundary layer have been established from Doppler mini-sodar measurements. Over the course of a 5-day period of measurements in the autumn time frame from 12 to 16 September 2003, values of the variance of the x- and y-components of the wind velocity lay in the interval from 0.001 to 10 m(2)/s(2), and for the z-component, from 0.001 to 1.2 m(2)/s(2). They were observed to grow during the morning hours (around 11: 00 local time) and in the evening (from 18: 00 to 22: 00 local time), which is explained by the onset of heating and subsequent cooling of the Earth's surface, which are accompanied by an increase in the motion of the air masses. Analysis of the obtained vertical profiles of the standard deviations of the three wind velocity components showed that growth of sigma(x) and sigma(y) with altitude is well described by a power-law dependence with its exponent varying from 0.22 to 1.3 as a function of the time of day while sigma(z) varies according to a linear law. At night (from 00: 00 to 5: 00 local time) the variance of the z-component changes from 0.01 to 0.56 m(2)/s(2), which is in good agreement with the data available in the literature. Fitting parameters are found and the error of the corresponding fits is estimated, which makes it possible to describe the diurnal dynamics of the wind velocity variance.