The Mobile Operated Doppler Lidar System (MODLS)

The Mobile Doppler Lidar and Soundings (MoDLS) facility currently consists of a Halo Photonics scanning Doppler Wind Lidar (DWL) and a Radiometrics Microwave Profiling Radiometer (MPR). There are two configurations in which MoDLS can be arranged. The current version of MoDLS is a 4-door flatbed pickup truck where the instruments are mounted to the flatbed portion of the truck. The reconfiguration includes the DWL, the MPR, a telescoping 6-meter mast that includes in-situ measurements and a RM-Young 81000 sonic anemometer. Undermounted hydraulic jacks are used to level the truck and maintain stability. A computer rack is mounted inside the back of the cab that holds the control computers and monitors. Helium tank boxes are mounted to the bed of the truck to hold helium tanks when radiosonde soundings accompany the platform

MoDLS deployed for a PERiLS deployment.

The other possible configuration has the lidar mounted inside an 18-ft enclosed trailer with the MPR mounted onto the front of the trailer. The trailer can be leveled using four leveling jacks located underneath the trailer. The lidar is mounted to a hand-crank lift that is lowered when traveling to provide the lidar protection. Once on site, the lift is then used to raise the lidar scanner through a roof hatch giving the lidar maximum height above ground clutter. Towards the front of the trailer, computer monitors are mounted inside to provide users real-time data viewing and lidar controls. A 10x8 ft area in the back of the trailer can be used to fill balloons for radiosonde soundings within a protected area. Although the trailer configuration can be good for long-term, stationary deployments, a new layout for the MoDLS improves mobility and increase ssafety for high wind situations.

The lidar can be operated in various configurations including 1-Hz vertically pointing measurements, RHI and PPI scans at any azimuths or elevations, and high resolution wind profiles. The current standard operational configuration includes a 15 deg 8 point VAD scan and 60 deg 6 point VAD scan every 5 minutes and 1-Hz vertical stare when not perfomring the VAD scans. All scans provide particle backscatter and velocity data as well as SNR. The range resolution and pulse length is also adjustable. The MPR used on MoDLS is the Radiometrics MP-3000A 35 channel radiometer. This radiometer is the same model that is used on the MIPS and the RaDAPS platforms. A Gill GMX 600 weather sensor will be used which provides wind, temperature/RH, precipitation, and pressure at 1-second and intervals. The sonic anemometer that will be added to the mast is a RM Young 81000 which provides u, v, and w wind components, sonic temperature, and speed of sound all provided at 10 Hz. These instruments will be powered by an undermounted 30 Amp Cummings diesel generator identical to the RaDAPS generator.

Lidar Specifications:
  • Wavelength: 1.5 µm
  • Sampling Rate: 1 Hz
  • Pulse Rate: 10 kHz
  • Max Range: 10 km
  • Vertical Resolution: 18-60 m

DWL velocity data from 27 March 2021 showing a building convective boundary layer and afternoon thermals.

Leveling jacks working their magic leveling the truck in the field.

Vertical velocity data from 5 May 2020 that shows multiple dynamic features.

The New MoDLS Truck Build

Prepping balloon soundings out of MoDLS in support of PERiLS.

Lidar 15 deg high-resolution VAD data depicting capturing a sudden wind shift that is assoicated with a current passage.