The eddy-covariance method is a tool that uses the high-frequency turbulent fluctuations within the atmosphere to determine energy and matter turbulent fluxes of different substances between the atmosphere and the underlying surface. The most important device is the sonic anemometer to measure the fluctuations of the three component wind vectors, with the first instruments developed in the 1960s in Moscow and tested in the Volga steppe region. This paper presents a general overview on ground-based sonic anemometers and Pitot tube meters for aircrafts with high response times. In this context, we evaluate methane fluxes in the Siberian permafrost area and aircraft measurements in the Lena region. Our approaches allow a spatial-frequency analysis of turbulent structures from the smallest scales to the mesoscale.