Comparison of atmospheric boundary layer soundings by a metric and a decimetric RASS

The vertical thermal profile of the lower atmosphere can be remotely measur ed by the Radio Acoustic Sounding System (RASS). A RASS operating at the ac oustic wavelength lambda (a)similar to 1 m was designed and developed twent y years ago. It is suitable for monitoring the temperature profile of the l ower troposphere and has been utilised for studies of the atmospheric bound ary layer in different conditions and for the application of control strate gies to air pollution emissions. The acoustic antenna is composed by 9 fold ed horns covering an area of 7x7 m(2); the two radar antennas are composed by arrays of dipoles with square reflector of 2.8x2.8 m(2) for each antenna . Therefore the metric RASS can be utilised only in a settled station. Rece ntly we have designed and developed a decimetric RASS (lambda (a) = 0.34 m) with smaller antennas, which can be used as a mobile system. It can be hou sed and carried by a trailer. As it is known, increasing the sounding frequ ency gives a decreasing of the sounding range. Comparisons of results obtai ned by both the metric and the decimetric RASS in different atmospheric con ditions are presented and discussed. (C) 2001 Elsevier Science Ltd. All rig hts reserved.