Abstract
Evaluation of the cloud seeding effect is a challenge due to lack of directly physical observational evidence. In this study, an approach for directly observing the cloud seeding effect is proposed using a 1548 nm coherent Doppler wind lidar (CDWL). Normalized skewness was employed to identify the components of the reflectivity spectrum. The spectrum detection capability of a CDWL was verified by a 24.23-GHz Micro Rain Radar (MRR) in Hefei, China (117°15′ E, 31°50′ N), and different types of lidar spectra were detected and separated, including aerosol, turbulence, cloud droplet, and precipitation. Spectrum analysis was applied as a field experiment performed in Inner Mongolia, China (112°39′ E, 42°21′ N ) to support the cloud seeding operation for the 70th anniversary of China’s national day. The CDWL can monitor the cloud motion and provide windshear and turbulence information ensuring operation safety. The cloud-precipitation process is detected by the CDWL, microwave radiometer (MWR) and Advanced Geosynchronous Radiation Imager (AGRI) in FY4A satellites. In particular, the spectrum width and skewness of seeded cloud show a two-layer structure, which reflects cloud component changes, and it is possibly related to cloud seeding effects. Multi-component spectra are separated into four clusters, which are well distinguished by spectrum width and vertical velocity. In general, our findings provide new evidence that the reflectivity spectrum of CDWL has potential for assessing cloud seeding effects.
Highlights
A method based on spectra analysis using a coherent Doppler wind lidar (CDWL) was developed for cloud-precipitation measurements, incorporating satellite and microwave radiometer (MWR)
The clouds were not penetrated completely, the two-layer structure of normalized skewness and spectrum width is detected in the layer warmer than 0 °C after seeding, which is similar to the melting layer structure
Multi-component spectra including cloud and precipitation are separated into four clusters, which have distinguishable distribution characteristics of spectrum width and vertical velocity
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Pathfinder Satellite Observations (CALIPSO), Ice, Cloud, and land Elevation Satellite (ICESat) [21,22,23,24,25] Other measurements such as polarization lidar [26,27,28], unmanned aerial vehicles [29], C- and W-band dual-polarization radars [30,31] can help ice cloud detection and the tracking of cloud seeding. The Doppler wind lidar as an active optical remote sensing instrument measures the radial velocity accurately; these are primarily applied in detecting windshear [32], turbulence [33,34,35,36], aircraft vortex [37], fog [38,39], the atmosphere boundary layer [40], and gravity waves [41] under clear air conditions [42,43,44,45].
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