Lidar observations of latent heat flux profiles in cold sectors of extratropical cyclones

• Applicant: Dr. Andreas Schäfler
• Subject Area: Atmospheric Science
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 552696968

Turbulent fluxes exchange heat, momentum and moisture between the ocean and the atmosphere and, thus, crucially influence the atmospheric and oceanic circulation from weather to climate scales. Despite their importance, fluxes are rarely observed and so their spatial and temporal distribution is not well-known. This uncertainty translates into the parametrized representation of fluxes in numerical weather prediction (NWP), which play a crucial role in the predictability of weather, in particular of High Impact Weather (HIW) events, such as storms, heavy precipitation or droughts. Such HIW in the midlatitudes crucially depends on transient cyclones, which redistribute warm and cold air, drive strong winds and, hence, give rise to turbulent fluxes. Latent heat fluxes (LHFs) in cold sectors of cyclones have an important preconditioning influence. They moisten the marine boundary layer (MBL) air that is subsequently advected into newly developing cyclones where it affects latent heating and precipitation. In this project innovative measurements of LHF profiles in the cold sector of cyclones and a characterization of the MBL are proposed using combined wind and water vapor lidar observations during the North Atlantic Waveguide, Dry Intrusion, and Downstream Impact Campaign (NAWDIC). The high accuracy and extended spatial coverage of these observations will enable a more accurate evaluation of NWP. In particular, we aim to identify systematic, weather system-relative errors in remote oceanic regions to give guidance for future improvements of the observation and analysis systems crucial for accurately predicting HIW.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1294: Atmospheric and Earth System Research with the "High Altitude and Long Range Research Aircraft" (HALO)
• Co-Investigators: Professor Dr. George Craig; Dr. Christoph Kiemle; Dr. Martin Wirth; Dr. Benjamin Witschas