Recent Results of the Land Atmosphere Feedback Experiment (LAFE)

Description

The Land-Atmosphere Feedback Experiment (LAFE) was a field effort performed at the ARM SGP site during August 2017. The objectives of LAFE are: I. Determine turbulence profiles and investigate new relationships among gradients, variances, and fluxes II. Map surface momentum, sensible heat, and latent heat fluxes using a synergy of scanning wind, humidity, and temperature lidar systems III. Characterize land-atmosphere (L-A) feedback and the moisture budget at the SGP site via the new LAFE sensor synergy IV. Verify large-eddy simulation model runs and improve turbulence representations in mesoscale models. For this purpose, a novel synergy of scanning lidar and remote sensing systems was designed and applied for simultaneous measurements of land-surface fluxes and horizontal and vertical transport processes in the planetary boundary layer (PBL). Also, the impact of spatial inhomogeneities of the soil and the land cover on L-A feedback was studied using the scanning capability of the instruments as well as soil, vegetation, and surface flux measurements. In this presentation, the status of the scientific work on the LAFE objectives is presented. This includes the following achievements: I. Simultaneous measurement of momentum, latent heat, and sensible heat flux profiles in the convective atmospheric boundary layer. First comparisons with similarity theory. II. First range-dependent active remote sensing of surface layer moisture, temperature, and wind profiles in the atmospheric surface layer. Comparison of these results with in-situ measurements at the LAFE towers and with Monin-Obukhov similarity theory (MOST). The measurements deviate substantially from the expectations based on MOST and question the applicability of MOST in terrain with significant land-surface heterogeneity. III. Determination of L-A metrics entirely based on observations such as Ek's relative humidity tendency. First attempt to close the water vapor budget in a domain around the SPG site are also shown. IV. Finally, our scientific approach to study and to improve parameterizations of atmospheric turbulence in mesoscale models and a corresponding ensemble model design are presented.