Borneo vortex and mesoscale convective rainfall
We have investigated how the Borneo vortex develops over the equatorial South China Sea under cold surge conditions in December during the Asian winter monsoon. Composite analysis using reanalysis and satellite data sets has revealed that absolute vorticity and water vapour are transported by strong...
Saved in:
Main Authors: | , , |
---|---|
Other Authors: | |
Format: | Article |
Language: | English |
Published: |
2014
|
Subjects: | |
Online Access: | https://hdl.handle.net/10356/100027 http://hdl.handle.net/10220/19656 |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Institution: | Nanyang Technological University |
Language: | English |
id |
sg-ntu-dr.10356-100027 |
---|---|
record_format |
dspace |
spelling |
sg-ntu-dr.10356-1000272020-09-26T21:35:03Z Borneo vortex and mesoscale convective rainfall Koseki, Shunya Koh, Tieh Yong Teo, Chee Kiat School of Physical and Mathematical Sciences Earth Observatory of Singapore Temasek Laboratories DRNTU::Science::Physics::Meteorology and climatology We have investigated how the Borneo vortex develops over the equatorial South China Sea under cold surge conditions in December during the Asian winter monsoon. Composite analysis using reanalysis and satellite data sets has revealed that absolute vorticity and water vapour are transported by strong cold surges from upstream of the South China Sea to around the Equator. Rainfall is correspondingly enhanced over the equatorial South China Sea. A semi-idealized experiment reproduced the Borneo vortex over the equatorial South China Sea during a "perpetual" cold surge. The Borneo vortex is manifested as a meso-α cyclone with a comma-shaped rainband in the northeast sector of the cyclone. Vorticity budget analysis showed that the growth/maintenance of the meso-α cyclone was achieved mainly by the vortex stretching. This vortex stretching is due to the upward motion forced by the latent heat release around the cyclone centre. The comma-shaped rainband consists of clusters of meso-β-scale rainfall cells. The intense rainfall in the comma head (comma tail) is generated by the confluence of the warmer and wetter cyclonic easterly flow (cyclonic southeasterly flow) and the cooler and drier northeasterly surge in the northwestern (northeastern) sector of the cyclone. Intense upward motion and heavy rainfall resulted due to the low-level convergence and the favourable thermodynamic profile at the confluence zone. In particular, the convergence in the northwestern sector is responsible for maintenance of the meso-α cyclone system. At both meso-α and meso-β scales, the convergence is ultimately caused by the deviatoric strain in the confluence wind pattern but is significantly self-enhanced by the nonlinear dynamics. Published version 2014-06-11T04:28:00Z 2019-12-06T20:15:21Z 2014-06-11T04:28:00Z 2019-12-06T20:15:21Z 2014 2014 Journal Article Koseki, S., Koh, T. Y., & Teo, C. K. (2014). Borneo vortex and mesoscale convective rainfall. Atmospheric Chemistry and Physics, 14(9), 4539-4562. 1680-7324 https://hdl.handle.net/10356/100027 http://hdl.handle.net/10220/19656 10.5194/acp-14-4539-2014 en Atmospheric chemistry and physics © Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License. application/pdf |
institution |
Nanyang Technological University |
building |
NTU Library |
country |
Singapore |
collection |
DR-NTU |
language |
English |
topic |
DRNTU::Science::Physics::Meteorology and climatology |
spellingShingle |
DRNTU::Science::Physics::Meteorology and climatology Koseki, Shunya Koh, Tieh Yong Teo, Chee Kiat Borneo vortex and mesoscale convective rainfall |
description |
We have investigated how the Borneo vortex develops over the equatorial South China Sea under cold surge conditions in December during the Asian winter monsoon. Composite analysis using reanalysis and satellite data sets has revealed that absolute vorticity and water vapour are transported by strong cold surges from upstream of the South China Sea to around the Equator. Rainfall is correspondingly enhanced over the equatorial South China Sea. A semi-idealized experiment reproduced the Borneo vortex over the equatorial South China Sea during a "perpetual" cold surge. The Borneo vortex is manifested as a meso-α cyclone with a comma-shaped rainband in the northeast sector of the cyclone. Vorticity budget analysis showed that the growth/maintenance of the meso-α cyclone was achieved mainly by the vortex stretching. This vortex stretching is due to the upward motion forced by the latent heat release around the cyclone centre. The comma-shaped rainband consists of clusters of meso-β-scale rainfall cells. The intense rainfall in the comma head (comma tail) is generated by the confluence of the warmer and wetter cyclonic easterly flow (cyclonic southeasterly flow) and the cooler and drier northeasterly surge in the northwestern (northeastern) sector of the cyclone. Intense upward motion and heavy rainfall resulted due to the low-level convergence and the favourable thermodynamic profile at the confluence zone. In particular, the convergence in the northwestern sector is responsible for maintenance of the meso-α cyclone system. At both meso-α and meso-β scales, the convergence is ultimately caused by the deviatoric strain in the confluence wind pattern but is significantly self-enhanced by the nonlinear dynamics. |
author2 |
School of Physical and Mathematical Sciences |
author_facet |
School of Physical and Mathematical Sciences Koseki, Shunya Koh, Tieh Yong Teo, Chee Kiat |
format |
Article |
author |
Koseki, Shunya Koh, Tieh Yong Teo, Chee Kiat |
author_sort |
Koseki, Shunya |
title |
Borneo vortex and mesoscale convective rainfall |
title_short |
Borneo vortex and mesoscale convective rainfall |
title_full |
Borneo vortex and mesoscale convective rainfall |
title_fullStr |
Borneo vortex and mesoscale convective rainfall |
title_full_unstemmed |
Borneo vortex and mesoscale convective rainfall |
title_sort |
borneo vortex and mesoscale convective rainfall |
publishDate |
2014 |
url |
https://hdl.handle.net/10356/100027 http://hdl.handle.net/10220/19656 |
_version_ |
1681058858769842176 |