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Data gathering

Experimental data gathering

The first cycle of measurements was performed in summer, above the flat area of Zymlyanskaya steppe in Rostov-na-Donu region. Measurements of fluctuations of the streamwise and vertical components of wind velocity were performed by two-component sonic anemometer of continuous radiation with capacitor microphones. Measurements of temperature fluctuations were performed with the aid of resistance thermometer. Sensors of the instruments were installed on pantograph mast which enabled to quickly move them to different heights, varying from 0.5 m to 5 m above the vegetation level.

Measurement were performed from 10 to 12 a.m. (summer daylight saving time) in conditions of convection. Average wind velocity at the 5 meters height was about 5 m/s.

With the aid of multichannel registrator the simultaneous recordings of pulsations of temperature and velocity components were made. Duration of each recording was 10 -- 18 minutes with sampling rate of 80 Hz for each channel. Measurements were performed consequently at the heights of 5m, 2.5m, 1.3m, 0.6m, that enables to trace dependence from the stratification parameter.

The second cycle of measurements was carried out in conditions of a big city, in the center of Moscow. Instruments were placed on a balcony facing the inner yard, at the level of 3-storey house roof (8 meters above the ground). Pulsations of vertical component of wind velocity were measured by sonic anemometer; simultaneously, pulsations of the temperature were measured by the resistance thermometer. Recordings of 10 to 18 minutes duration were made at various times of a day. At The observations time coincided with the intensive thawing of snow; the warm air mass was hanging above the snowy surface. The wind was low, temperature at the height of 8 meters varied from 5 to 15 degrees (Celsius), at the ground level it was close to zero. These conditions allowed stratification to remain stable during all 24 hours.

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