For the purposes of this study, all available data from the acoustic sounding of the atmosphere are used.
From 1st August to 31st October 2008 sodar measurements were made from 7:00 a.m. to 6:00 p.m. From 8th December 2008 to 27th July 2009 the sodar functioned continuously and after that until December 2009 only during the day, from 7:30 a.m. to 9:40 a.m. After December 2009 the sodar was worked continuously.”
During the years of operating mode, the manufacturer provided periodic updates to the sodar software, resulting in a gradual increase in the optimal height of the output profiles.
1* – continuous profiles to fixed heights with simultaneous availability of 12 sodar output parameters (wind direction /WD/, wind speed and its dispersion /WS, sigWS/, vertical wind speed and its dispersion /W, sigW /, horizontal wind speed components and their dispersions /U, sigU, V, sigV/, eddy dissipation rate /EDR/, turbulent intensity /TI/ and turbulent kinetic energy /TKE/);
2 – continuous profiles with a minimum height of 110 m and simultaneous availability of 12 sodar output parameters;
3 – profiles consisting of a minimum of 3 points in height satisfying the wind direction condition and permitting an interruption only for lack of data;
The color dots on the red line (averaged profile) indicates the availability of the individual profiles involved in the averaging at given altitudes and the green area indicates averaged profiles’ dispersion.
The nocturnal marine air masses during the cold part of the year are defined by the winter profiles and partly by these in the transition seasons at which the synoptic conditions with eastern and northeastern wind components were dominant. Therefore, the observed sigW and TKE peaks at a height of 300 m are associated, with a slightly unstable or neutral marine PBL height, due to the relatively warm sea surface during the cold part of the year.
Can be associated with the height of the IBL formed by a dominant factor the surface roughness change.
The flow of Archimedes force (buoyancy flow: β = sigW3/z) or the assessment of turbulence generation due to convection is expected and has high values near the ground and decreases with height to reach the value distinctive for the higher layer in the atmosphere. High BP values can also be expected in the interaction or entrainment zone over a convective boundary layer where transport of warmer air masses from the stable layer aloft takes place.
Under condition 1* (calculated from 159 individual profiles):
The negative peaks are an indicator of convective or neutral IBL and non-disturbed marine air masses over it during the night.
Under condition 3:
Thus confirming that at night in the cold season the height of the marine ABL (slightly unstable or neutral) is about 300 m.
The seasonal cross-sections of stability classes probabilities with height are presented here. The atmospheric stability classes according to the Pasquill-Gifford classification using the σϕ method are defined by two main types of nocturnal individual profiles with applied condition 2.
Nocturnal land air masses during the warm part of the year
Nocturnal land air masses during the cold part of the year
Nocturnal marine air masses during the warm and cold part of the year