The Raman-shifted Eye-safe Aerosol Lidar (REAL) is a scanning elastic backscatter lidar owned and operated by Chico State Enterprises on behalf of the California State University Chico. It was deployed to a site near Tonopah, Nevada from July - September of 2023 for the M2HATS field experiment.
Its deployment to M2HATS was sponsored by the National Science Foundation's Physical and Dynamic Meteorology Program under award 2054969. Dr. Chenning Tong from Clemson University is the lead principal investigator for the project.
The objective of having REAL at M2HATS is to observe the horizontal vector wind field on scales larger than the linear array. The technique is similar to particle image velocimetry (PIV) used in laboratories.
Unlike many atmospheric lidars today, the REAL transmits a smaller number (10 per second) of high energy (130 mJ) pulses in order to form images while scanning "rapidly" (4 degrees per second is its typical scan rate). No integration of the backscatter data over time is required. Backscatter is sampled at 100 million samples per second resulting in a data point every 1.5 m along the beam. The images can be used to observe the spatial structure of the aerosol distribution and derive vector wind fields.
Vector flow fields are derived in real-time using the algorithm named "Typhoon". This algorithm was developed by Dr. Pierre Dérian. It was written for execution on Nvidia GPGPUs to process scanning aerosol lidar data at Chico State under NSF funding. You can read about the details here:
We also have a webpage discussing it:
Near real-time results can be viewed through the following webpages:
In general, we have found that the technique works the best in Tonopah in the afternoons when the boundary layer is convective and the wind is strong. During these times, REAL is able to visualize the structure of the gusts and the vector flow fields in and around the gusts. Because the CSAT3 sonic anemometers from the linear array are directed to the south and we are focused on unstable conditions, we often turn off the REAL at night when the flow is from the north and stable.
REAL was revitalized after 8 years of non-operation in Chico thanks to support from NSF and NCAR EOL Staff: Scott Spuler, Bruce Morley, Robert Stillwell, Ben Crane, Dexter Rowland, and Pierre Dérian (through Chico State Enterprises). You can read more about the preparation of the REAL for M2HATS at the following link:
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