Influence of Synoptic Pattern and Low-Level Wind Speed on Intensity and Diurnal Variations of Orographic Convection in Summer Over Pearl River Delta, South China

Xiaona Rao, Kun Zhao, Xingchao Chen, Anning Huang, Ming Xue, Qinghong Zhang, Mingjun Wang

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Based on 5 years of operational Doppler radar data, the influences of atmospheric synoptic patterns and low-level prevailing wind speed on the intensity and diurnal variations of summer orographic convection occurrence frequencies over Pearl River Delta, South China, have been investigated. Results show that the inland orographic convection and rainfall generally occurs under synoptic pattern characterized with the prevailing southwesterly wind within the lower troposphere. The summer orographic convection over the mountains in northeastern Pearl River Delta is not only controlled by the orographic thermal conditions but also the dynamic forcing with the increase of wind speed. Owing to the strong windward mechanical lifting and moisture transport associated with the strong ambient onshore winds, the number of convection occurrences characterized by a dominant diurnal afternoon peak occurs much more frequently in the high-wind speed days. While due to the weak orographic mechanical lifting and moisture supply in the low-wind speed days, the number of convection occurrences in the afternoon decreases considerably and two comparable peaks occur in the afternoon and early morning. The nighttime peak in the low-wind speed days is mainly attributed to the nocturnal acceleration of the low-level southwesterly wind associated with the inertial oscillation and the corresponded enhanced windward lifting effects.

Original languageEnglish (US)
Pages (from-to)6157-6179
Number of pages23
JournalJournal of Geophysical Research: Atmospheres
Volume124
Issue number12
DOIs
StatePublished - Jun 27 2019

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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