Preprints
https://doi.org/10.5194/acp-2021-177
https://doi.org/10.5194/acp-2021-177

  07 Apr 2021

07 Apr 2021

Review status: this preprint is currently under review for the journal ACP.

Microphysical process of precipitating hydrometeors from warm-front mid-level stratiform clouds revealed by ground-based lidar observations

Yang Yi1,2,3, Fan Yi1,2,3, Fuchao Liu1,2,3, Yunpeng Zhang1,2,3, Changming Yu1,2,3, and Yun He1,2,3 Yang Yi et al.
  • 1School of Electronic Information, Wuhan University, Wuhan 430072, China
  • 2Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan 430072, China
  • 3State Observatory for Atmospheric Remote Sensing, Wuhan430072, China

Abstract. Mid-level stratiform precipitations during the passage of warm front were detailedly observed on two occasions (light and moderate rain) by a 355-nm polarization lidar and water-vapor Raman lidar, both equipped with waterproof transparent roof windows. The hours-long precipitation streaks shown in the lidar signal (X) and volume depolarization ratio (δv) reveal some ubiquitous features of the microphysical process of precipitating hydrometeors. We find that for the light rain case, surface rainfall begins as supercooled liquid-drop-dominated hydrometeors fall out of their liquid parent cloud at altitudes above the 0 °C level, and most liquid drops quickly freeze into ice particles (δv > 0.25) during the first 100–200 m of their descent, where humid aerosol particles exist. Subsequently, the falling hydrometeors yield a dense layer with an ice/snow bright band occurring above and a liquid-water bright band occurring below (separated by a lidar dark band) as a result of crossing the 0 °C level. The ice/snow bright band might be a manifestation of local hydrometeor accumulation. Most falling raindrops shrink or vanish in the liquid-water bright band due to evaporation, whereas a few large raindrops fall out of the layer. We also find that a prominent depolarization δv peak (0.10–0.35) always occurs at an altitude of approximately 0.6 km during surface rainfall, reflecting the collision-coalescence growth of falling large raindrops and their subsequent spontaneous breakup. The microphysical process (at ice-bright-band altitudes and below) of moderate rain resembles that of the light rain case, but more large-sized hydrometeors are involved.

Yang Yi et al.

Status: open (until 02 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Yang Yi et al.

Yang Yi et al.

Viewed

Total article views: 183 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
148 31 4 183 0 4
  • HTML: 148
  • PDF: 31
  • XML: 4
  • Total: 183
  • BibTeX: 0
  • EndNote: 4
Views and downloads (calculated since 07 Apr 2021)
Cumulative views and downloads (calculated since 07 Apr 2021)

Viewed (geographical distribution)

Total article views: 168 (including HTML, PDF, and XML) Thereof 168 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 15 Apr 2021
Download
Short summary
Our lidar observations reveal the complete microphysical process of hydrometeors falling from mid-level stratiform clouds. We find that the surface rainfall begins as supercooled mixed-phase hydrometeors fall out of a liquid parent cloud base. We find also that the collision-coalescence growth of precipitating raindrops and subsequent spontaneous breakup always occur around 0.6-km altitude during surface rainfalls. Our findings provide new insights into the stratiform precipitation formation.
Altmetrics