Determination of the speed and direction of transport of localized atmospheric formations with the aid of sodar three-point observations

A method to determine the speed and direction of transport of some atmosphe ric formations with clearly defined boundaries (for example, convective vor tices or catabatic flows) with the aid of acoustic sounding is described. T he data obtained with the use of three vertically directed antennas of an a coustic echo sounder (sodar), which form a triangle in the horizontal plane , are analyzed. It is shown that the logarithm of the intensity of echo sig nals, along with the vertical wind velocity, is a reliable indicator in det ermining the boundaries of such formations. The transport velocity vector i s determined from time delays in the passage of the formation boundary betw een three antenna pairs. The time delay is determined from the first moment s of the mutual correlation functions of the signals for each antenna pair. To calculate the components of the transport velocity vector, an improved approach, which involves the least-squares method to solve the inconsistent system of equations, is used. This allows one to obtain more stable estima tes for the speed and direction of transport. The experimental data obtaine d in Turbigo (Italy) are used to illustrate and to test the method describe d.