BASTA: A 95-GHz FMCW Doppler radar for cloud and fog studies

Julien Delanoë (1) , Alain Protat (2) , Jean-Paul Vinson (3) , Williams Brett (3) , Christophe Caudoux (3) , Fabrice Bertrand (3) , Jacques Parent Du Châtelet (4, 1) , Ruben Hallali (1, 4) , Laurent Barthès (1) , Martial Haeffelin (5) , Jean-Charles Dupont (5)

1 SPACE - LATMOS
2 BoM - Australian Bureau of Meteorology [Melbourne]
3 LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
4 CNRM - Centre national de recherches météorologiques
5 IPSL - Institut Pierre-Simon-Laplace

Doppler cloud radars are amazing tools to characterize cloud and fog properties and to improve their representation in models. However commercially-available cloud radars (35 and 95 GHz) are still very expensive, which hinders their widespread deployment. In this study we present the development of a lower-cost semi-operational 95 GHz Doppler cloud radar called BASTA for Bistatic rAdar SysTem for Atmospheric studies. In order to drastically reduce the cost of the instrument a different approach is used compared to traditional pulsed radars: instead of transmitting a large amount of energy for a very short time period (as a pulse), a lower amount of energy is transmitted continuously. In the paper we show that using specific signal processing technique the radar can challenge expensive radars and provide high-quality measurements of cloud and fog. The latest version of the instrument has a sensitivity of about -50 dBZ at 1 km for 3 s integration and a vertical resolution of 25 m. BASTA radar currently uses four successive modes for specific applications: the 12.5 m vertical resolution mode is dedicated to fog and low clouds, the 25 m mode is for liquid and ice mid-tropospheric clouds and the 100 m and 200 m are ideal for optically-thin high-level ice clouds. We also highlight the advantage of such a radar for calibration procedures and field operations. The radar comes with a set of products dedicated to cloud and fog studies. For instance, cloud mask, corrected Doppler velocity and multi mode products combining high sensitivity mode and high resolution modes are provided.

Domaines: Météorologie

Julien Delanoë, Alain Protat, Jean-Paul Vinson, Williams Brett, Christophe Caudoux, et al.. BASTA: A 95-GHz FMCW Doppler radar for cloud and fog studies. Journal of Atmospheric and Oceanic Technology, 2016, 33 (5), pp.1023-1038. ⟨10.1175/JTECH-D-15-0104.1⟩. ⟨insu-01278272⟩