Mesosphere and Lower Thermosphere wind speed determination using data from the radio forward scatter BRAMS network

BRAMS (Belgian RAdio Meteor Stations) is a network using forward scatter of radio waves on ionized meteor trails to study meteoroids. It is made of a dedicated transmitter and of 44 receiving stations located in or near Belgium. The transmitter emits a circularly polarized CW radio wave with no modulation at a frequency of 49.97 MHz and with a power of 130 W. Each receiving station uses a 3-element zenith pointing Yagi antenna. The first stations used analog ICOM-R75 receivers and a PC. Since 2018, new improved stations have been installed using digital RSP2 receivers, a GPSDO and a Raspberry Pi, providing better dynamic, sensitivity and stability. Recently, several methods have been developed to reconstruct trajectories from meteor echoes recorded at several BRAMS stations. These methods rely on time delays between meteor echoes, pre-t0 phase measurements, and sometimes information from a radio interferometer, or a combination of all the methods. This has opened the possibility to use the BRAMS network to determine the Mesosphere and Lower Thermosphere (MLT) wind speeds using data coming from a large number of meteor echoes.In this work, we will present the status of the BRAMS network and discuss how BRAMS data can be used to determine MLT wind speeds.  Using a forward scatter system with a very large number of stations allows to increase the number of detections, to increase the altitudinal coverage, and to relax the homogeneity assumption.  Simulations will be considered to estimate the impact of the meteoroid trajectory reconstruction uncertainties (in particular the uncertainty on altitude of the specular reflection point) on the wind speeds retrieval.  We will discuss which temporal and spatial resolutions of the MLT wind field measurements can be achieved.  We will finally discuss several upcoming upgrades of the network and their potential impact on this work.