The Land-Atmosphere Feedback Experiment: Theory and Design

The Land-Atmosphere Feedback Experiment (LAFE) will deploy several state-of-the-art scanning lidar and remote sensing systems to the Deparment of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site. These instruments will augment the ARM instrument suite in order to collect a dataset for studying feedback processes between the land-surface and the atmosphere. The novel synergy of remote sensing systems will be applied for simultaneous measurements of land-surface fluxes as well as horizontal and vertical transport processes in the atmospheric convective boundary layer (CBL). The impact of spatial inhomogeneities of the soil-vegetation continuum on land-surface atmosphere (LSA) feedback will be studied using the scanning capability of the instrumentation. LAFE will be conducted in August 2017.

The remote sensing system synergy consists of three components:

1)   The SGP water-vapor and temperature Raman lidar (SRL), the SGP Doppler lidar (SDL), and the NCAR water-vapor DIAL (NDIAL) mainly in vertical staring modes to measure mean profiles and gradients of moisture, temperature, and horizontal wind. The SRL and the SDL will also measure profiles of higher-order turbulent moments in the water vapor and wind fields and profiles of the latent heat flux.

2)   A novel scanning lidar system synergy consisting of the NOAA High-Resolution Doppler lidar (HRDL), the University of Hohenheim (UHOH) water-vapor differential absorption lidar (UDIAL), and the UHOH temperature rotational Raman lidar (URL). These systems will perform coordinated range-height indicator (RHI) scans from just above the canopy level to the lower troposphere including the interfacial layer of the CBL. The optimal azimuth is to the ENE of the SGP central facility, which takes advantage of both changes in the surface elevation and different crop types that are planted along that path.

3)   The University of Wisconsin SPARC and the University of Oklahoma CLAMPS systems operating two vertically pointing atmospheric emitted radiance interferometers (AERIs) and two Doppler lidar (DL) systems scanning cross track to the central RHI for determining the surface friction velocity and the horizontal variability of temperature, moisture, and wind. Thus, both the variability of surface fluxes as well as CBL dynamics and thermodynamics over the SGP site will be studied for the first time.

The combination of these three components will enable us to estimate both the divergence of the latent heat profile and the advection of moisture. Thus, the moisture budget in the SGP domain can be studied. Furthermore, the simultaneous measurements of surface and entrainment fluxes as well as the daily cycle of the CBL thermodynamic state will provide a unique data set for characterizing LSA interaction in dependence of large-scale and local conditions such as soil moisture and the state of the vegetation. The measurements will also be applied for the development of improved parameterizations of surface fluxes and turbulence in the CBL. The latter is possible because mean profiles, gradients, higher-order moments and fluxes are measured simultaneously.

This presentation will provide an overview of LAFE, the instrument deployment strategy, and a discussion of several of relationships that we want to test directly with these lidar observations.