Preprints
https://doi.org/10.5194/acp-2021-113
https://doi.org/10.5194/acp-2021-113

  25 Mar 2021

25 Mar 2021

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

Tracking the influence of cloud condensation nuclei on summer diurnal precipitating systems over complex topography in Taiwan

Yu-Hung Chang1, Wei-Ting Chen1, Chien-Ming Wu1, Chistopher Moseley1, and Chia-Chun Wu2 Yu-Hung Chang et al.
  • 1Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan
  • 2National Science and Technology Center for Disaster Reduction, New Taipei City, Taiwan

Abstract. This study focuses on how aerosols, serving as cloud condensation nuclei (CCN), affect the properties of the summertime diurnal precipitation under the weak synoptic weather regime over complex topography in Taiwan. Semi-realistic large-eddy simulations (LESs) were carried out using the vector vorticity equation model with high-resolution Taiwan topography (TaiwanVVM) and driven by idealized observational soundings. Since the aerosol effects on convection could be specific during different stages of the life cycle, we perform object-based tracking analyses, which diagnose both the spatial and temporal connectivity of convective systems, to highlight the convective clouds that are locked by topography and reduce the stochastic features of convection. The statistical analyses on the tracked extreme convective systems highlight the differences in structural characteristics of convection between the experiments with clean and normal CCN scenarios. For the orographic-locking regime, the effects of CCN on the diurnal precipitating systems are more significant. The precipitation initiation is postponed significantly, which prolongs the development of local circulation and convection. The occurrence of the cloud objects with extreme maximum rain rates doubles. Also, the P99 of the maximum rain rate and the maximum cloud size during the lifetime of the diurnal precipitating systems increase by 16.9 % and 6.7 %, respectively. This study demonstrates that the object-based tracking analyses of extreme precipitating systems are useful to investigate the responses of orographic-driven diurnal convection to CCN.

Yu-Hung Chang et al.

Status: open (until 20 May 2021)

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

Yu-Hung Chang et al.

Data sets

TRMM 3B42 Goddard Earth Sciences Data and Information Services Center (GES DISC) https://doi.org/10.5067/TRMM/TMPA/3H/7

CWB rain gauge and sounding observations Ministry of Science and Technology & Chinese Culture University, Data Bank for Atmospheric and Hydrologic Research https://dbar.pccu.edu.tw/

GLDAS v2 soil moisture Beaudoing, H. and M. Rodell, NASA/GSFC/HSL https://doi.org/10.5067/342OHQM9AK6Q

Yu-Hung Chang et al.

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Short summary
The impacts of increasing cloud condensation nuclei on the summertime diurnal precipitation under weak synoptic weather regime over complex topography in Taiwan were investigated, by applying object-based tracking analyses to the semi-realistic large-eddy simulations. Our results highlight that, for convective clouds that are locked by topography, precipitation initiation is postponed significantly, and the occurrence of cloud objects with extreme maximum rain rates doubles.
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