dl: Doppler Lidar

The Doppler Lidar (DL) is an active remote-sensing instrument that provides range- and time-resolved measurements of the line-of-sight component of air velocity (i.e., radial velocity) and attenuated aerosol backscatter. The DL operates in the near-infrared and is sensitive to backscatter from atmospheric aerosol, which are assumed to be ideal tracers of atmospheric wind fields.

The DL works by transmitting short pulses of infrared laser light into the atmosphere Atmospheric aerosols scatter a small fraction of that light energy back to the transceiver, where it is collected and recorded as a time-resolved signal. From the delay between the outgoing pulse and the backscattered signal, the instrument infers the distance to the scattering volume.

Coherent detection is used to measure the Doppler frequency shift of the backscatter signal. This is accomplished by mixing the backscatter signal with a reference laser beam (i.e., local oscillator) of known frequency. The onboard signal processor then determines the Doppler frequency shift from the spectrum of the mixed signal. The Doppler frequency shift and thus the radial air velocity is determined from the peak of the Doppler spectrum. The attenuated backscatter is determined from the energy content of the Doppler spectra.

The DL provides accurate measurements of radial velocity in regions of the atmosphere where aerosol concentrations are high enough to ensure good signal-to-noise ratio. Thus, valid data are usually limited to the atmospheric boundary layer where aerosol is ubiquitous. Valid measurements can also be obtained in elevated aerosol layers or in optically thin clouds above the boundary layer. Most of the ARM DLs have full upper-hemispheric scanning capability, enabling 3D mapping of turbulent flows in the atmospheric boundary layer. With the scanner pointed vertically, the DL provides height- and time-resolved measurements of vertical velocity.

Measurements

Locations

  • Fixed
  • AMF1
  • AMF2
  • AMF3

Related Publications

2017

Schwartz S, D Huang, and D Vladutescu. 2017. "High-resolution photography of clouds from the surface: Retrieval of optical depth of thin clouds down to centimeter scales." Journal of Geophysical Research: Atmospheres, , 10.1002/2016JD025384. ONLINE.

Lundquist J, J Wilczak, R Ashton, L Bianco, W Brewer, A Choukulkar, A Clifton, M Debnath, R Delgado, K Friedrich, S Gunter, A Hamidi, G Iungo, A Kaushik, B Kosović, P Langan, A Lass, E Lavin, J Lee, K McCaffrey, R Newsom, D Noone, S Oncley, P Quelet, S Sandberg, J Schroeder, W Shaw, L Sparling, C Martin, A Pe, E Strobach, K Tay, B Vanderwende, A Weickmann, D Wolfe, and R Worsnop. 2017. "Assessing State-of-the-Art Capabilities for Probing the Atmospheric Boundary Layer: The XPIA Field Campaign." Bulletin of the American Meteorological Society, 98(2), 10.1175/BAMS-D-15-00151.1.

2016

Newman JF, TA Bonin, PM Klein, S Wharton, and RK Newsom. 2016. "Testing and validation of multi-lidar scanning strategies for wind energy applications." Wind Energy, 19(12), 10.1002/we.1978.

Bu L, H Pan, KR Kumar, X Huang, H Gau, X Liu, and D Kim. 2016. "Lidar and Millimeter-Wave Cloud Radar (MWCR) techniques for joint observations of cirrus in Shouxian (32.56n, 116.78e), China." Journal of Atmospheric and Solar-Terrestrial Physics, 148, 10.1016/j.jastp.2016.08.013.

Wulfmeyer V and D Turner. 2016. Land-Atmosphere Feedback Experiment (LAFE) Science Plan. Ed. by Robert Stafford, DOE ARM Climate Research Facility. DOE/SC-ARM-16-038.

Borque P, E Luke, and P Kollias. 2016. "On the unified estimation of turbulence eddy dissipation rate using Doppler cloud radars and lidars." Journal of Geophysical Research: Atmospheres, 121(10), 10.1002/2015jd024543.

Newsom R. 2016. Analysis of the Uncertainty in Wind Measurements from the Atmospheric Radiation Measurement Doppler Lidar during XPIA: Field Campaign Report. Ed. by Robert Stafford, DOE ARM Climate Research Facility. DOE/SC-ARM-15-091.

Wainwright CE, PM Stepanian, and KG Horton. 2016. "The role of the US Great Plains low-level jet in nocturnal migrant behavior." International Journal of Biometeorology, 60(10), 10.1007/s00484-016-1144-9. ONLINE.

2015

Klein PM, TA Bonin, JF Newman, DD Turner, PB Chilson, CE Wainwright, WG Blumberg, S Mishra, M Carney, EP Jacobsen, S Wharton, and RK Newsom. 2015. "LABLE: A Multi-Institutional, Student-Led, Atmospheric Boundary Layer Experiment." Bulletin of the American Meteorological Society, 96(10), 10.1175/bams-d-13-00267.1. ONLINE.

Lamer K and P Kollias. 2015. "Observations of fair-weather cumuli over land: Dynamical factors controlling cloud size and cover." Geophysical Research Letters, 42(20), 10.1002/2015gl064534.


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