Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South China
Abstract Convection is highly active on tropical islands. Based on a 3‐year radar climatology over Hainan Island, a mountainous tropical island in South China, we identified a distinct spatial dependence of convection initiation (CI) on the speed of the large‐scale low‐level flow. Convection initiat...
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| Format: | Article |
| Language: | English |
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Wiley
2021-08-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1029/2021GL094382 |
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| author | Lei Zhu Lanqiang Bai Guixing Chen Y. Qiang Sun Zhiyong Meng |
| author_facet | Lei Zhu Lanqiang Bai Guixing Chen Y. Qiang Sun Zhiyong Meng |
| author_sort | Lei Zhu |
| collection | DOAJ |
| description | Abstract Convection is highly active on tropical islands. Based on a 3‐year radar climatology over Hainan Island, a mountainous tropical island in South China, we identified a distinct spatial dependence of convection initiation (CI) on the speed of the large‐scale low‐level flow. Convection initiates most prominently over the lee‐side plains in high‐wind conditions while over mountains in low‐wind conditions. Quasi‐idealized numerical simulations suggest that mountain ridges stimulate the formation and growth of horizontal convective rolls (HCRs) over the lee‐side plains in high‐wind conditions. These HCRs subsequently intersect with sea‐breeze fronts, which enhances the low‐level convergence favoring CI on the lee‐side plains of the island. During low‐wind conditions, thermally driven circulations control and favor CI over the mountains during the day. The findings highlight that the response of local circulations to the lower‐troposphere ambient flow and diurnal thermal heating is an important aspect of convection initiation on the island. |
| format | Article |
| id | doaj-art-83cf795af04d40efbb9bf34539e87fad |
| institution | OA Journals |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2021-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-83cf795af04d40efbb9bf34539e87fad2025-08-20T02:18:54ZengWileyGeophysical Research Letters0094-82761944-80072021-08-014816n/an/a10.1029/2021GL094382Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South ChinaLei Zhu0Lanqiang Bai1Guixing Chen2Y. Qiang Sun3Zhiyong Meng4Key Laboratory of Meteorological Disaster (KLME) Ministry of Education and Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC‐FEMD) Nanjing University of Information Science and Technology Nanjing ChinaSchool of Atmospheric Sciences Sun Yat‐sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) Zhuhai ChinaSchool of Atmospheric Sciences Sun Yat‐sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) Zhuhai ChinaAtmospheric and Oceanic Sciences Program Princeton University Princeton NJ USADepartment of Atmospheric and Oceanic Sciences School of Physics Peking University Beijing ChinaAbstract Convection is highly active on tropical islands. Based on a 3‐year radar climatology over Hainan Island, a mountainous tropical island in South China, we identified a distinct spatial dependence of convection initiation (CI) on the speed of the large‐scale low‐level flow. Convection initiates most prominently over the lee‐side plains in high‐wind conditions while over mountains in low‐wind conditions. Quasi‐idealized numerical simulations suggest that mountain ridges stimulate the formation and growth of horizontal convective rolls (HCRs) over the lee‐side plains in high‐wind conditions. These HCRs subsequently intersect with sea‐breeze fronts, which enhances the low‐level convergence favoring CI on the lee‐side plains of the island. During low‐wind conditions, thermally driven circulations control and favor CI over the mountains during the day. The findings highlight that the response of local circulations to the lower‐troposphere ambient flow and diurnal thermal heating is an important aspect of convection initiation on the island.https://doi.org/10.1029/2021GL094382convection initiationtropical islandmonsoonsea breezehorizontal convective roll |
| spellingShingle | Lei Zhu Lanqiang Bai Guixing Chen Y. Qiang Sun Zhiyong Meng Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South China Geophysical Research Letters convection initiation tropical island monsoon sea breeze horizontal convective roll |
| title | Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South China |
| title_full | Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South China |
| title_fullStr | Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South China |
| title_full_unstemmed | Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South China |
| title_short | Convection Initiation Associated With Ambient Winds and Local Circulations Over a Tropical Island in South China |
| title_sort | convection initiation associated with ambient winds and local circulations over a tropical island in south china |
| topic | convection initiation tropical island monsoon sea breeze horizontal convective roll |
| url | https://doi.org/10.1029/2021GL094382 |
| work_keys_str_mv | AT leizhu convectioninitiationassociatedwithambientwindsandlocalcirculationsoveratropicalislandinsouthchina AT lanqiangbai convectioninitiationassociatedwithambientwindsandlocalcirculationsoveratropicalislandinsouthchina AT guixingchen convectioninitiationassociatedwithambientwindsandlocalcirculationsoveratropicalislandinsouthchina AT yqiangsun convectioninitiationassociatedwithambientwindsandlocalcirculationsoveratropicalislandinsouthchina AT zhiyongmeng convectioninitiationassociatedwithambientwindsandlocalcirculationsoveratropicalislandinsouthchina |