Latent Heat Flux by Raman Lidar and Wind Lidar system during Walineas Campaign.

The crucial parameter for characterizing the energy exchange between the Earth's surface and the atmosphere within the Atmospheric Boundary Layer (ABL) is the latent heat flux (LHF). This represents the speed at which energy stored as latent heat in water vapor molecules is transported into the ABL due to the turbulent convective movement of the air.

The integration of both lidar measurements provides a comprehensive perspective on atmospheric processes related to latent heat flux, significantly contributing to improving the understanding of the water cycle and associated meteorological phenomena. During the WaLiNeAs campaign (Water vapor Lidar Network Assimilation), a consortium of French, German, Italian, and Spanish research groups deployed a network of 6 autonomous Water Vapor (WV) Lidars in the French territory. This network delivers measurements with high vertical resolution and accuracy throughout the Western Mediterranean, starting in the fall of 2022 and addressing critical gaps in water vapor observations in the lower troposphere from current operational networks and satellites.

As part of the WaLiNeAs initiative, a Lidar system developed by the University of Basilicata was positioned near a Wind Lidar with the goal of collecting measurements of heat flux and turbulent kinetic energy (TKE). These two systems operated continuously for three months starting from the end of September 2022, covering the most favorable period in southern France and acquiring high-resolution measurements (10 seconds, 30 meters).

Acknowledgment

The authors acknowledge Next Generation EU Mission 4 “Education and Research” - Component 2: “From research to business” - Investment 3.1: “Fund for the realization of an integrated system of research and innovation infrastructures” - Project IR0000032 – ITINERIS.

This work was supported by the Agence Nationale de la Recherche (WaLiNeAs, Grant ANR-20-CE04-0001). This research was also funded by the Italian Ministry for Education, University and Research (grants STAC-UP and FISR2019-CONCERNING) and the Italian Space Agency (grants As-ATLAS and CALIGOLA).

References

[1] Flamant, C., Chazette, P., Caumont, O. et al. (2021) A network of water vapor Raman lidars for improving heavy precipitation forecasting in  southern      France: introducing the WaLiNeAs initiative. Bull. of Atmos. Sci.& Technol. 2, 10.

[2] Kiemle, W. A. Brewer, G. Ehret, R. M. Hardesty, A. Fix, C. Senff,  M. Wirtg, G. Poberaj and M. A. Lemone. (2007) Latent Heat Flux Profiles from Collocated Airborne Water Vapor and Wind Lidars during IHOP_2002. American Meteorological Society pp:627-639.

[3] Behrendt , V. Wulfmeyer1 , C. Senff , S. K. Muppa, F. Späth , D. Lange , N. Kalthoff , and A. Wieser. (2020). Observation of sensible and latent heat flux profiles with lidar Atmos. Meas. Tech., 13, 3221–3233.