ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 49 Issue 8 > 2023,49(8):958-971. DOI:10.7519/j.issn.1000-0526.2023.071001 Prev Next
Analysis of A Snowfall Event at Zhangjiakou on 29 November 2019 Based on Ka-Band Millimeter-Wavelength Radar and Aircraft Observations
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Abstract:
A snowfall event occurred in Zhangjiakou in 29-30 November 2019. The snowfall clouds were thoroughly analyzed based on millimeter-wavelength cloud radar observations and aircraft observations to explore the macro- and microphysical characteristics of the clouds. This snowfall event lasted from 14:00 BT 29 to 01:00 BT 30. Restricted by moisture transport and supply, the ground precipitation showed an increasing-decreasing-increasing tendency. The vertical depth of clouds varied distinctly with time. The maximum reflectivity of cloud radar was 25 dBz. The recorded time with ground precipitation more than 1 mm corresponded well to the period that cloud radar detected high values of reflectivity (10-15 dBz) and spectral width. The growing ice crystals and updraft air flows mainly existed above 4000 m. Positive values of radical velocity detected by cloud radar were mostly in mid-to-early stages of snowfall. Ice crystals were the dominated particles within clouds according to the sounding of airborne probes. Besides, graupels and aggregated particles were captured. As ice crystals〖JP2〗 were falling, they grew up through the microphysical processes of coalescence-collision and contact-freezing. Meanwhile the cloud radar observed magnitude of both radical velocity and spectral width were augmented. When ice crystals larger than 500 μm were detected, the reflectivity of cloud radar was greater than 0 dBz. In the heights 4400-4700 m, spectral width of cloud radar dramatically changed. These results could further help understand and analyze the macro-and microphysics of winter snowfall clouds and snowfall enhancement potentials in Zhangjiakou Region.
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