WaLiNeAs France

Abstract. During the WaLiNeAs field campaign, three lidars developed by the French research team working at the Laboratoire des Sciences du Climat et de l’Environnment (LSCE/CEA) operated during the autumn and winter 2022 and the summer 2023. Lidar measurement conditions are described hereafter.
The Weather and Aerosol Lidar (WALI) operated on the Thales Alenia Space location in Cannes during the WaLiNeAs field campaign. The lidar acquired data continuously from 04 October 2022 to 12 January 2023 with a few interruptions due to power outage. During daytime the vertical range was up to 2 km in altitude under clear sky condition and to 10 km during night-time.
The H_2 O Raman Ultraviolet Sounder 2 (HORUS-2) operated in Coursan and Toulouse during the WaLiNeAs field campaign. The lidar acquired data continuously from 06 October 2022 to 04 November 2022 in Coursan with interruptions due to power outage and laser failures. It acquired data continuously from 31 May 2023 to 25 September 2023 in Toulouse with two interruptions due to power outage and lidar maintenance. During daytime the vertical range is up to 2.5 km in altitude under clear sky condition and to 10 km during night-time.
The H_2 O Raman Ultraviolet Sounder 1 (HORUS-1) operated on the roof of the Port Camargue harbour office in Grau-Du-Roi during the WaLiNeAs field campaign. The lidar acquired data continuously from 26 October 2022 to 12 January 2023 with 2 brief interruptions due to lidar maintenance. During daytime the vertical range was up to 1.5 km in altitude under clear sky condition and to 7 km during night-time.
For all lidars, lidar data are inversed in terms of Water Vapor Mixing Ratio (WVMR), as a function of altitude. They have been time- and geo-localized. The database contains level 2 data products. Level 2 data are products of calibrated individual lidar profiles for WVMR. The dataset contains also data in terms of pressure, temperature and humidity acquired with a ground base weather station associated with the lidar.

Observing strategy. The WaLiNeAs campaign strategy was defined before the intensive campaign and presented in Flamant et al., 2021. The HORUS type lidar has been developed to measure water vapor autonomously in field conditions. HORUS lidars are embedded in enclosures manufactured by ArtConcept. They can be controlled remotely. The optical architecture of the lidars is inspired from the Raman detection channel of the WALI lidar described in Totems et al., 2021. WALI (Totems et al., 2021) was implemented in the Mobile Atmospheric Station (MAS) truck to measure WMVR profiles vertically from the ground. It has already been deployed during previous field measurement campaigns under similar measurement conditions as described in Chazette et al., 2014. During the campaign, lidars measured WVMR continuously with one profile acquired each minute with an initial vertical resolution equal to 0.75 m. Profiles were then averaged in time and altitude for a better range.
All lidars are part of the lidar network deployed around the western Mediterranean basin to study and forecast Heavy Precipitation Events (HPE) occurring during the autumn. HORUS-2 has been deployed in Toulouse during the summer 2023 as part of the WaLiNeAs campaign to study extreme weather events which can occur in south of France during the summer such as violent storms or heatwaves. Dataset will be used to study and understand meteorological processes occurring in the air column. Lidar data could be assimilated into meteorological mesoscale models such as the Application of Research to Operations at Mesoscale (AROME) model monitored by Météo-France to improve the capacity of the model to forecast HPE by using constraints in the lower part of the troposphere (see Flamant et al., 2021). Dataset will also be used to study and understand meteorological processes occurring in the air column.