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Your search keyword '"Hua, Dengxin"' showing total 133 results
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133 results on '"Hua, Dengxin"'

1. Microphysical Processes and Enhancement Effect of Natural Seeder-Feeder in Stratiform Snowfall Observed by Millimeter-Wave Cloud Radar

Author

Yuan, Yun, Di, Huige, and Hua, Dengxin

Abstract

Natural seeder-feeder is a common phenomenon in stratiform clouds precipitation. The quantitative evaluation of the enhancement effect of seeder-feeder plays an important role in improving the accuracy of weather forecasting and artificial weather operations. In this study, ground-based millimeter-wave cloud radar, microwave radiometer (MWR), and ground precipitation phenomenon instrument (GPPI) were used to observe the natural seeder-feeder process between double-layer clouds during ground snowfall in Xi’an, China for three years. A constrained small particle tracing method and an optimized fuzzy logic algorithm were proposed to achieve inversion of vertical air motions ( $V_{a}$ ) and particle terminal falling velocity ( $V_{f}$ ) and identify cloud phase states. The reflectivity factor (Z) (attenuation corrected) and mean Doppler velocity ( $V_{r}$ ) were used to identify the feeding and nonfeeding areas in low-level feeding clouds. The enhancement effect of seeding on cloud particles was quantitatively evaluated by analyzing the differences in Z, $V_{f}$ , and particle diameter (D) between the feeding and nonfeeding areas. Meanwhile, the enhancement effect of seeding on ground precipitation was analyzed. The statistical results show that after seeding, both cloud particles and ground precipitation significantly increased. The average-Z, $- V_{f}$ , and $- D$ of cloud particles in the feeding areas have increased by 10 dBZ, 0.75 m $\cdot $ s−1, and 0.5 mm compared with the nonfeeding areas, respectively. Compared with the nonfeeding period, the average ice water content (IWC), average number concentration ( $N_{T}$ ), mean particle diameter ( $D_{m}$ ), and maximum particle diameter (MPD) of ground precipitation particles during the feeding periods were [1.01–67.91], [1.04–35.37], [1.04–2.04], and [1.01–3.65] times, respectively.

Published
2025
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28. Investigation of the Spatial and Temporal Variation of Temperature and Water Vapor in Lower Troposphere Using the Combined Backward Raman Scattering LiDAR and Lateral Scanning Raman Scattering LiDAR

Author

Yang, Fan, Gao, Fei, Hua, Dengxin, and Stanic, Samo

Abstract

A novel Raman scattering LiDAR is proposed to achieve accurate measurements of atmospheric temperature and water vapor from the ground to the concerned height, in which a lateral scanning receiver is constructed to collect the lateral rotational and vibrational Raman scattering signals excited by the transmitted laser pulses from the backward Raman scattering LiDAR (BWRSL). The major advantages of the combined lateral scanning Raman scattering LiDAR (LSRSL) and BWRSL are the sharing of the transmitted laser and the measurements of temperature and water vapor without the effect of geometrical overlap function. To simplify the mechanical mounting and offer the commonality configuration, both polychromators in the LSRSL and BWRSL utilize the modular design with narrow-band interference filters to extract the high- and low-quantum-number transitions of the pure rotational Raman scattering signals and the vibrational Raman scattering signals of N2 and H2O. Different with the BWRSL in the profiling of Raman scattering signal in its dependence on the time elapsed after the transmission of the laser pulse, the profiling of the LSRSL is realized by the elevation angle scanning of the lateral receiver, in which four horizontally aligned telescopes mounted on a steerable frame are spatially separated to look at the vertical laser beam at a certain distance. The experimental measurements of both LSRSL system and BWRSL system are carried out with the temporal resolution of 16 min and the spatial resolution of 36 m. The retrieval results after data gluing shows that the combined BWRSL and LSRSL system can realize the detection of atmospheric temperature and water vapor from the ground to the height of 4.00 km. The error analysis shows that both deviation and statistical error of the atmospheric temperature are less than 1 K, and both deviation and statistical error of the water vapor mixing ratio are less than 0.5 g/kg within the detection height interval of 0–4.00 km.

Published
2024
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29. A 3.2-μm Wavelength Integrated Path Differential Absorption Lidar for Probing Open-Path Benzene Gas

Author

Liu, Jiahui, Li, Shichun, Wang, Yi, Hua, Dengxin, Xin, Wenhui, Gao, Fei, and Duan, Mingxuan

Abstract

We report on the application of two tunable interband cascade lasers (ICLs) with about 3.2- $\mu $ m wavelength in integrated-path differential absorption (IPDA) lidar and power-modulation integrated-path differential absorption (PM-IPDA) lidar experiments for probing open-path benzene concentration. To demonstrate the performance of the PM-IPDA lidar, we investigate the performance in an open-path atmosphere according to the comparative experiment of the IPDA lidar and the PM-IPDA lidar. To the best of our knowledge, it is the first comparative experiment of the IPDA lidar and the PM-IPDA lidar in the mid-infrared band for probing open-path benzene concentration. Data from these laboratory experiments indicate the effectiveness of the IPDA lidar and the PM-IPDA lidar, and also that the PM-IPDA lidar can reduce the impact of 1/f noise on detection performance. Data from these open-path atmosphere experiments with a time resolution of 0.1 s indicate that the detection limit of the IPDA lidar is about 0.89 mg $\cdot $ m3 and that the detection limit of the PM-IPDA lidar is approximately 0.66 mg $\cdot $ m3. Hence the detection limit of the PM-IPDA lidar is approximately 26% lower than that of the IPDA lidar.

Published
2024
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