This is a repost from the now defunct Whatever-Weather.com website.
The US Department of Energy runs the Atmospheric Radiation Measurement (ARM) Climate Research Facilities. It started out in 1992 with their first long term location in Oklahoma. According to their history website, the focus is on obtaining more data for use in climate circulation models and future prediction by focusing on radiative energy and the effects of clouds. They now have many fixed and mobile facilities around the world to collect data in this endeavor. Many scientists from around the world with many different agencies (including NOAA and NASA) cycle in and out conducting a variety of forms of research and not just scientists at the Department of Energy facilities.
From ARM Website
As the name implies it works similar to our traditional radars (X-band, C-Band, etc…) but instead of using a radio wave spectrum, it uses a laser in the near-IR spectrum (1.5 microns) to collect radial velocity and back scatter. It is sensitive enough to detect micron-sized back scatter particles with velocity precisions as good as 10cm/sec. This means it can use the micron particles as tracers for low level wind direction and speed. It can provide three-dimensional flows of the boundary layer and can measure vertical velocity measurements when pointed vertically. ARM has three of these: one deployed in Oklahoma, one in Darwin, Australia, and one with their mobile facility, which for 2012, will be in Cape Cod, MA.
The next type of LiDAR is the High Spectral Resolution LiDAR (HSRL). It provides calibrated measurements of aerosol optical depth, back scatter, cross-section, and depolarization. Measurements are computed from ratios of the particulate scattering to the measured molecular scattering. This provides a precise calibration and prevents dirt of precipitation from polluting the calibration. The ARM has three of these instruments in the field. One is located on the North Slope of Alaska, and two mobile units, which will be in the Cape Cod, MA area this year.
The Micropulse LiDAR system is the third of four systems they have. It is designed primarily to detect cloud heights. It uses the same time-return process as radar to collect data. Further post-processing of the data can also get more data about the particle characteristics. The ARM has fourteen of these instruments. One is on the North Slope of Alaska, one is in Oklahoma, and three are in the western Pacific in Papa New Guinea, Nauru Island, and Darwin, Australia. The other eight are mobile units scattered across the world. The locations are in the Black Forest in Germany, the Azores in Portugal, in Shouxian, China, in Niger, India, Point Reyes, CA, and Steamboat Springs, CO.
Image from ARL Website
The last type of research LiDAR is the Rayman LiDAR system. The system is in the UV light range with bands at 355, 387, or 408nm. It is designed to measure vertical profiles of water vapor, mixing ratio, Nitrogen, cloud base height, backscattered radiation and depolarization ratio. There are two deployed, one in Oklahoma, and one in Darwin, Australia.
Image from ARL Website
Next time even though warm weather is upon us we will go into snowpack studies from airplane-mounted and tripod-mounted LiDAR on the ground.
Sources and More Information:
Doppler LiDAR http://www.arm.gov/instruments/dl
HRSL LiDAR http://www.arm.gov/instruments/hsrl
Micropulse LiDAR: http://www.arm.gov/instruments/mpl
Rayman LiDAR: http://www.arm.gov/instruments/rl
(c) 2012 Charles Schoeneberger
Chuck Schoeneberger is a University of North Dakota graduate in Atmospheric Sciences. He has his Masters in Geographic Information Systems from St Mary’s University of Minnesota in Winona, MN. He also has worked with LiDAR processing from a position at Aerometric, an aerial survey company based in Sheboygan, WI and ortho imagery from Aerometric and Airborne Data Systems of Redwood Falls, MN. He lives in the Twin Cities metropolitan area. One of his passions is learning about technologies that can be applied to disaster response for public safety before and after damaging weather events.