| Popis: |
Based on the results of postprocessing of minisodar measurements of three wind velocity components and their variances in the lower 200-meter layer of the atmosphere, the diurnal hourly dynamics of the kinetic energy of the atmosphere reduced to unit air mass and its component ETKE (caused by turbulent pulsations of the wind velocity) and EMKE (caused by the mean wind velocity) are analyzed focusing on the turbulent kinetic energy. It is shown that during 24 hour continuous minisodar observations, ETKE was low up to 50 m, increased from 50 to 100 m, and fast increased at higher altitudes. A significant influence of the time of day on the observation results was noted. Thus, at night the kinetic energy did not exceed 20 J/kg and then increased with time from 20 to 50 J/kg. It reached a maximum in the morning. After sunrise, the turbulent kinetic energy quickly decreased, and the system underlying surface – near-surface air layer went into equilibrium. As a consequence, the spread of turbulent kinetic energy values decreased. The most significant changes were observed at altitudes of 100–200 m.Tthe time of day had no significant influence at altitudes of 50–100 m, and the ETKE values were low and remained practically unchanged with time. Irrespective of the time of day, the maximum turbulent kinetic energy was observed at altitudes of 100–200 m, which poses the greatest danger to unmanned aerial vehicles. The corresponding numerical estimations are presented. |
