The measurements taken by aircraft are very useful. On the one hand, they provide data in areas where there are no monitoring stations – similar programmes are also run with ships and buoys. On the other, information from the free atmosphere is gathered, where practically no other measurements are otherwise taken. During take-off and landing, the sensors also provide information on the stratification of the atmosphere and thus supplement/increase the density of the radio sounding monitoring network.
More recently, there has been increasing interest in novel methods for gathering aircraft-based observations, especially mode-selective (Mode-S) enhanced surveillance (EHS)-derived data allowing estimates of wind and temperature at the aircraft’s location.