COMPARISON OF THERMAL ADVECTION MEASUREMENTS BY CLEAR-AIR RADAR AND RADIOSONDE TECHNIQUES

Vertical profiles of the horizontal wind have been measured every 4 min by a clear‐air radar (stratosphere‐troposphere radar), and vertical profiles of temperature have been obtained every 2 hours by three radiosonde soundings in the same zone in Brittany during the Mesoscale Frontal Dynamics Project “FRONTS 87” campaign. Radar thermal advection ATR is deduced from the thermal wind equation using the measured real horizontal wind instead of the geostrophic wind. Radiosonde thermal advection ATS is determined directly from the sounding station data sets of temperature gradients and also approximated from the thermodynamic equation by the temperature tendency ∂T/∂t\p. These approximations, applied during a frontal passage, show the same general features and magnitude of the thermal advection, giving a preliminary but encouraging conclusion for a possible real‐time utilization of clear‐air radars to monitor thermal advection and to identify its characteristic features. Copyright 1990 by the American Geophysical Union.