Posters

Abstract

The building of wind farms in increasingly extreme environments presents various challenges to wind resource assessment. The remoteness of many such sites can make deployment of conventional mast-mounted anemometry difficult and expensive, with remote sensing devices often serving as the only practically viable and preferred wind measurement tool. All commercially available wind Lidars record the Doppler shift when a laser beam is scattered by particles moving in the atmosphere. Depending upon the device type, this may present a challenge when Lidars are deployed at high altitude as the air can become exceptionally clear, thereby reducing the signal levels for such devices. As a continuous-wave Lidar technology, the ZX300 has a significantly higher output power than is typically found in other Lidar designs, maximising signal levels and increasing the chances of being able to measure in clean air conditions. However, there have been few published case studies demonstrating Lidar measurement performance in such conditions. This study presents availability statistics from two deployments of ZX300 Lidar systems in Chile, separated by 5 years. Both are at high altitude (over 2100m) in the Atacama Desert and exhibit low pollution levels and characteristically clean air. (NB: Further data sets are available, and results will be included in the final submission if permission is received from the data owners.) Results Histograms of the signal levels (in terms of backscatter) for the two Atacama sites have been plotted alongside a histogram of the backscatter levels from January to March 2024 at a UK lowland site (the UK Remote Sensor Test Site). Backscatter levels from both Atacama sites are an order of magnitude lower than those from the UK site, demonstrating the low concentration of aerosols in the atmosphere. 10‐minute-averaged wind speed measurement availability statistics for the three data sets are shown in the tables below.  Atacama A: Altitude: 2256m  183 days, 2018-07-01 to 2018-12-31   99.86% 99.76% 99.51% 99.27% 98.98% 98.72% 98.34% 97.95% 97.59% 97.13% 97.13% 18m 38m 58m 78m 98m 118m 138m 158m 178m 198m 218m Figure 1:  10‐minute-averaged wind speed measurement availability in clear-air: Deployment A Atacama B: Altitude: 2104m  80 days, 2023-10-01 to 2023-12-20   99.97% 99.57% 99.42% 99.25% 99.02% 98.82% 98.61% 98.48% 98.43% 98.14% 98.07% 18m 38m 58m 78m 98m 118m 138m 158m 178m 198m 218m Figure 2:  10‐minute-averaged wind speed measurement availability in clear-air: Deployment B Overall Availability UK Remote Sensor Test Site 20m 38m 45m 70m 91m 120m 150m 180m 200m 250m 99.9% 99.7% 99.6% 98.8% 98.4% 97.6% 96.7% 96.0% 94.6% 93.0%   Figure 3: 10‐minute-averaged wind speed measurement availability: Jan-Mar 2024 at the UK Remote Sensor Test Site Discussion Two ZX300 Lidar deployments, at altitudes above 2000m in the Atacama Desert, delivered over 97% data availability up to 218m. These results are consistent with performance at the UK Remote Sensor Test Site, despite signal levels being an order of magnitude lower. This demonstrates the ZX300’s resilience to variations in aerosol concentration found in extreme environments and provides confidence to those considering similar deployments in future.