A method is developed to calculate nonlinear zonal, s_x, and meridional, s_y, longitudinal advective accelerations from MU radar observations with antenna beam scanning in eight directions. The results of measurements of s_x and s_y at altitudes of 2 - 18 km on April 16-18, 1997, are presented. The values of s_x and s_y are mainly between -0.01 m s^-2 and 0.01 m s^-2 with increases up to ±0.04 m s^-2 during tens of minutes to several hours in regions with vertical scales up to several kilometers. Such extremes are more frequent at the altitudes of tropo-stratospheric jet at 10 - 15 km and may indicate regions of inclination from geostrophic balance and of increased generation of atmospheric waves.