Weather radar refractivity variability in the boundary layer of the atmosphere

Abstract

International audienceWeather radars could measure the change in the refractive index of air in the boundary layers of the atmosphere. This technic uses the phase of the signal from ground targets located around weather radars. This measure provides information on atmospheric refractivity which depends on meteorological parameters such as temperature, pressure and humidity. During the HyMeX (Hydrological cycle in Mediterranean Experiment) campaign, refractivity measurements were implemented on several S-band radars of ARAMIS (Application Radar à la Météorologie Infra-Synoptique) French radar network. A study has shown that phase changes have a high temporal variability on both daily and seasonal scales. This variability could be very probably linked to the boundary layer turbulent level. In order to sample temporal and spatial phase variability, an analysis based on a 1-year dataset from S-band and C-band ARAMIS radars and Automatic Weather Stations (AWS) measurements is presented. This inter-comparison, of both radar and AWS measurements, gives a better knowledge of the relationship between the variability of radar refractivity measurements and turbulent level. In further investigations, particular attention will be paid to the phase time derivate and spatial variations during a campaign in controlled conditions. This will help answering the question of recovering boundary-layer turbulent level information from radar refractivity measurements