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These files contain 24 hour periods of data collected from the CLAMPS1 Halo Streamline Doppler lidar. While not conducting other scans, the lidar directs the beam to zenith, allowing for the measurement of vertical velocity. These data were collected during the American Wake Experiment (AWAKEN) project. The CLAMPS1 facility was deployed at the Rolling Meadows Golf Course east of Enid, OK.
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| Investigator(s): | Petra Klein (pkklein@ou.edu) Elizabeth Smith (elizabeth.smith@noaa.gov) 0000-0001-6673-1576 Tyler Bell (tyler.bell@noaa.gov) Joshua Gebauer (joshua.gebauer@noaa.gov) Lydia Bunting (lydia.bunting@noaa.gov) Arianna Jordan (arianna.jordan@ou.edu) |
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| Data Format: | netcdf | ||||||||
| File Naming Convention: | he typical naming convention is clampsdlfpC2.c1.YYYYMMDD.HHmmss.cdf, following closely to ARM file naming convention. The ‘fp’ refers to ‘fixed point,’ which is our case zenith. The files have time and height dimensions. | ||||||||
| Abstract: | These files contain 24 hour periods of data collected from the CLAMPS1 Halo Streamline Doppler lidar. While not conducting other scans, the lidar directs the beam to zenith, allowing for the measurement of vertical velocity. These data were collected during the American Wake Experiment (AWAKEN) project. The CLAMPS1 facility was deployed at the Rolling Meadows Golf Course east of Enid, OK. |
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| Purpose: | These data were collected during the American Wake Experiment (AWAKEN) project. The sites where the two CLAMPS facilities deployed, including the Rolling Meadows Golf Course, were not part of the original AWAKEN proposal to ARM. As such, OU, NSSL, and LLNL deployed a profiling lidar and CLAMPS trailer at the golf course and at ARM's E36 site for 3 months in 2022. The ZephIR300 profiling lidar collects wind speed, direction and quasi-turbulence measurements from 10m to 300m. CLAMPS can measures the wind, tempeature and moisture profile from approximately 100m to 3km. CLAMPS's scanning lidar, which provided these data, is a Halo Photonics. During this project it made VAD scans every 10-15 minutes. With the combination of these instruments winds were able to be observed from near-ground level to around 3km. Collectively, profiles of wind, temperature, and moisture can tell us how the ABL evolves through time. E36 measurements, which are expected to have nearly no wind farm influence can be compared to observations at this site, which is surrounded on most sides by wind farms. Understanding how wind farms affect the ABL is an important consideration especially considering the recent abundance and growth of wind farms in the southern Great Plains Region. |
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| Data Usage: | The Halo Streamline is a commercial platform. The Doppler lidar (DL) is an active remote-sensing instrument that provides range- and time-resolved measurements of radial velocity, attenuated backscatter, and signal-to-noise ratio (SNR). The principle of operation is similar to radar in that pulses of electromagnetic energy (infrared in this case) are transmitted into the atmosphere; the energy scattered back to the transceiver is collected and measured as a time-resolved signal. From the time delay between each outgoing transmitted pulse and the backscattered signal, the distance to the scatterer is inferred. The radial or line-of-sight velocity of the scatterers is determined from the Doppler frequency shift of the backscattered radiation. The DL uses a heterodyne detection technique in which the return signal is mixed with a reference laser beam (i.e., local oscillator) of known frequency. An onboard signal-processing computer then determines the Doppler frequency shift from the power spectra of the heterodyne signal. The energy content of the Doppler spectra can also be used to estimate attenuated backscatter. The DL operates in the near-infrared (IR;1.5 microns) and is sensitive to backscatter from micron-sized aerosols. Aerosols are ubiquitous in the lower troposphere and behave as ideal tracers of atmospheric winds. In contrast to radar, the DL is capable of measuring radial velocities under clear-sky conditions with very good precision – typically ~10 cm/sec (Newsom and Krishnamurthy 2020). It is important to note that DL scans are fully user configurable, so special attention should be paid to the scan strategy applied for this dataset. The Doppler lidar provides range-resolved, line-of-sight measurements of radial velocity, intensity (signal-to-noise ratio [SNR]+1), and attenuated backscatter. This measurement of vertical velocity is much more direct than that provided with the VAD scan files. For the AWAKEN campaign, the CLAMPS1 Doppler lidar collected vertical stares at a 1-second time resolution (same as CLAMPS2 vertical stares time resolution during AWAKEN). The provided files provide the intensity field (SNR+1), which can be used as a ‘filter’ for noise. A good rule of thumb cutoff is 1.01. Data are provided in netcdf format. | ||||||||
| Arm Sites: | sgp | ||||||||
| Content Time Range: | Begin: 2022-10-03 End: 2022-12-21 | ||||||||
| Instrument(s): | Doppler Lidar |
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| Data Type: | Atmospheric Boundary Layer-Wind Farm Interactions |
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| Additional Missing Info: | Additional details available in readme file: AWAKENStaresRead-me_CLAMPS1DopplerLidarRMGC. Read more about CLAMPS and find some tools to get started at apps.nssl.noaa.gov/CLAMPS/ | ||||||||