Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors (CHEESEHEAD) – The German Contribution

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The overall goal of the submitted proposal is the investigation of the impact of surface heterogeneity on the spatio-temporal variability and dynamics of the atmospheric boundary layer. This activity is planned as a cooperation with American (USA) partners, who concurrently submit a corresponding proposal to NSF. The German contribution will be large eddy simulations (LES) of turbulent transport processes in order to investigate the causes of the apparent closure gap in the surface energy balance. This will allow for examining the partitioning between sensible and latent heat flux and developing a parametrisation determining the meso-scale flux contribution of the order of 1 km. a high-density extensive detector array recording data with a high spatio-temporal resolution in the area under investigation is required for a successful accomplishment of this aim. A central 420 m tall meteorological tower will be surrounded by 20 eddy covariance stations, supplemented by airborne measurements, passive and active remote sensing devices. The proposed German contribution to this field campaign is the deployment of two scanning wind LiDAR systems and a newly developed scanning LiDAR system for the measurement of temperature and water-vapor distributions. The latter is a combination of a rotational Raman-LiDAR (Temperature) and a differential absorption LiDAR (DIAL, absolute humidity). Only a continuous operation of this system yields the spatio-temporal resolution required for the overall project. Particularly, water vapor profiling with the DIAL technique on a mobile platform in the field is highly innovative. Thus, establishing this technology in the field of boundary-layer meteorology is one goal of this proposal.