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 journalArticle

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

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diurnal variations
diurnal variation
wind speed
rivers
summer
China
convection
wind velocity
Rivers
river
moisture
occurrences
Doppler radar
Moisture
oscillation
troposphere
Troposphere
Convection
morning
mountains

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

Cite this

@article{e080359bf5d74ca6bac97bc8803d9fd7,
title = "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",
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.",
author = "Xiaona Rao and Kun Zhao and Xingchao Chen and Anning Huang and Ming Xue and Qinghong Zhang and Mingjun Wang",
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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. / Rao, Xiaona; Zhao, Kun; Chen, Xingchao; Huang, Anning; Xue, Ming; Zhang, Qinghong; Wang, Mingjun.

In: Journal of Geophysical Research: Atmospheres, Vol. 124, No. 12, 27.06.2019, p. 6157-6179.

Research output: Contribution to journalArticle

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AU - Xue, Ming

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AU - Wang, Mingjun

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AB - 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.

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