Remote-Sensing Measurements of the Diurnal Structure of the Mixed Layer over the SGP
Poster PDF
Authors
Marian B. Clayton — Science Systems and Applications, Inc. (SSAI)
Richard A. Ferrare — NASA - Langley Research Center
David D. Turner — NOAA- Global Systems Laboratory
Tyler Thorsen — NASA - Langley Research Center
Robert E. Holz — University of Wisconsin/CIMMS
Ralph Kuehn — University of Wisconsin Madison
Edwin W. Eloranta — University of Wisconsin
Willem Jacobus Marais — University of Wisconsin - CIMSS
Rob K Newsom — Pacific Northwest National Laboratory
Category
Boundary layer structure, including land-atmosphere interactions and turbulence
Description
The thermodynamic structure and evolution of the Mixed Layer (ML) must be accurately represented in numerical models, as errors can lead to significant biases in many atmospheric processes, including radiative fluxes, cloud properties and processes, precipitation processes, aerosol and chemical processes, and dispersion. In order to study the diurnal behavior of the ML over the DOE ARM Southern Great Plains (SGP) site, we use a combination of SGP remote-sensing measurements: Raman lidar (RLID) measurements of aerosol backscatter, water vapor mixing ratio, and temperature, University of Wisconsin High-Spectral-Resolution Lidar (HSRL) measurements of aerosol backscatter and aerosol depolarization, Doppler lidar (DL) measurements of wind velocity, and Atmospheric Emitted Radiance Interferometer (AERI) retrievals of temperature for these studies. The UW HSRL measurements were acquired during the Combined HSRL And Raman lidar Measurement Study (CHARMS) (mid-July through September, 2015).
We use the lidar measurements to identify sharp gradients in aerosols and water vapor at the top of the ML and have used these algorithms to derive ML heights. Based on comparisons with boundar-layer (BL) heights derived from potential temperature profiles from radiosondes, the ML height determined in this manner is normally a good proxy for the daytime BL height. However, retrieving ML heights via lidar measurements of water vapor and aerosol gradients is problematic in the presence of elevated aerosol and water-vapor layers that are often observed, especially at night. Consequently, we also compute ML heights using potential temperature profiles derived from Raman lidar and AERI measurements. We also investigate how the DL measurements of horizontal wind profile observations and vertical velocity can be combined with the RLID+AERI observations to improve the accuracy of the ML height estimation by evaluating the bulk Richardson number together with the potential temperature. In addition, we use the lidar measurements to determine the fraction of aerosol optical thickness within and above the ML.
