Institut Franco-Allemand de Recherches de Saint-Louis (ISL), B.P. 34, 68301 Saint-Louis Cedex, France
Institut des Microtechniques de Franche-Comté (IMFC), Institut de Génie Énergétique (IGE), 2 avenue Jean Moulin, 90000 Belfort, France
The experiments on the propagation of acoustic air waves in the low atmospheric layer show a large influence of aerological parameters. In particular, there were only few measurements carried out outdoors to approach thermal turbulent values . There are many thermal sensors ranging from a simple platinum resistance to quartz crystal. Each technology has some advantages depending on the type of measurement one intends to perform. To explore the earth boundary layer, we chose a micro-thermocouple of type S. Its small size (1.27 µm) allows us to obtain a low calorific capacity and a high thermal conductance. On the other hand, its sensitivity is low and it was necessary to associate an amplifier with a gain of 100 000. The whole device was set outside on a bar 2 m above the ground. The different experiments carried out with one or several microthermocouples showed very small turbulences of different types depending on the role of the different layers in the low atmosphere. They also enabled to visualize convection due to the ground or due to the wind as a function of time.
(Received December 23 1998)
(Revised June 3 1999)
(Accepted June 3 1999)
(Online publication August 15 1999)