Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

dl > Doppler LidarInstrument Type(s) > Baseline • Guest

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.

Purpose

Understand boundary layer dynamics.

Locations

  • Fixed
  • AMF1
  • AMF2
  • AMF3

Data Details

Developed By Ewan OConnor
Contact Ewan OConnor
Resource(s) Data Directory
ReadMe
Data format netcdf
Site TMP
Content time range 21 October 2010 - 5 February 2023
Attribute accuracy No formal attribute accuracy tests were conducted
Positional accuracy No formal positional accuracy tests were conducted
Data Consistency and Completeness Threshold on signal to noise.
Access Restriction No access constraints are associated with this data.
Use Restriction Please notify PI when using data.
File naming convention yyyymmdd_tmp-_halo-doppler-lidar--.nc, where sitecode = M1, M2, id = instrument id, product = wind, dpol, copol

2023

O’Donnell S, A Akherati, Y He, A Hodshire, J Shilling, C Kuang, J Fast, F Mei, Siegfried Schobesberger7, J Thornton, J Smith, S Jathar, and J Pierce. 2023. "Look Up: Probing the Vertical Profile of New Particle Formation and Growth in the Planetary Boundary Layer with Models and Observations." Journal of Geophysical Research: Atmospheres, 128(3), e2022JD037525, 10.1029/2022JD037525.

2022

Newsom RK and R Krishnamurthy. 2022. Doppler Lidar (DL) Instrument Handbook. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM/TR-101. 10.2172/1034640.

Williams I and S Qiu. 2022. "Long‐term observations of turbulence vertical velocity spectra in a convective mixed layer: Dependence on land‐surface forcing in the U.S. Southern Great Plains." Journal of Geophysical Research: Atmospheres, 127(24), e2022JD037137, 10.1029/2022JD037137.

Pryor S, F Letson, T Shepherd, and R Barthelmie. 2022. "Evaluation of WRF simulation of deep convection in the US Southern Great Plains." Journal of Applied Meteorology and Climatology, 62(1), 10.1175/JAMC-D-22-0090.1.

Sanchez Gomez M, J Lundquist, J Mirocha, R Arthur, D Munoz-Esparza, and R Robey. 2022. "Can lidars assess wind plant blockage in simple terrain? A WRF-LES study." Journal of Renewable and Sustainable Energy, 14(6), 063303, 10.1063/5.0103668.


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