Comparison of horizontal velocity measurements between the ST-VHF Provence radar and a VHF small profiler using two different antenna configurations

Abstract

In the classical development of wind profiler systems, the VHF range (40-60 MHz) has been generally selected for high altitudes explorations (ST and MST systems) and the UHF range oriented mainly towards low altitudes soundings (T systems). Preliminary experiments in LSEET have shown that it was possible to investigate as low as 300 m with a low-power, small 50 MHz profiler radar in a classical configuration (squared, nxn). But using a small antenna array involves an increasing of the half-power beamwidth and of the overlapping in adjacent gates in oblique directions, and inverse methods have to be applied for atmospheric parameters retrieval. A new configuration of the antenna (two crossed lines) leads to decrease the oblique angle and the half-power beantwidth, and allows to reduce overlapping between adjacent gates. In this paper, measurements from the small profiler in these two different configurations (squared and crossed configurations) and from the Provence radar (reference radar) will be compared, without using inverse methods. Validities of small radar measurements for horizontal velocities will be given in a quantitative way, as a function of the altitude and of the signal-to-noise ratio. Conclusions will be clearly exposed, and will indicate that measurements from the small profiler in crossed configuration are not strongly affected by overlapping, and that then horizontal velocities can be interpreted directly without using inverse methods.

Keywords

• wind profiler systems
• radar measurements
• signal-to-noise ratio
• provence radar
• antennenarray
• windprofiler