Synoptic-dynamic analysis of early dry-season rainfall events in the Vietnamese Central Highlands
The Central Highlands are Vietnam's main coffee growing region. Unusual
wet spells during the early dry season in November and December
negatively affect two growing cycles in terms of yield and quality. The
meteorological causes of wet spells in this region have not been
thoroughly studied to date. Using daily rain gauge measurements at nine
stations for the period 1981-2007 in the Central Highlands, four
dynamically different early dry-season rainfall cases were investigated
in depth: 1) the tail end of a cold front, 2) a tropical depression-type
disturbance, 3) multiple tropical wave interactions, and 4) a cold
surge with the Borneo vortex. Cases 1 and 4 are mainly extratropically
forced. In case 1, moisture advection ahead of a dissipating cold front
over the South China Sea led to high equivalent potential temperature in
the southern highland where this air mass stalled and facilitated
recurrent outbreaks of afternoon convection. In this case, the low-level
northeasterly flow over the South China Sea was diverted around the
southern highlands by relatively stable low layers. On the contrary,
low-level flow was more orthogonal to the mountain barrier and high
Froude numbers and concomitant low stability facilitated the westward
extension of the rainfall zone across the mountain barrier in the other
cases. In case 3, an eastward-traveling equatorial Kelvin wave might
have been a factor in this westward extension, too. The results show a
variety of interactions of large-scale wave forcings,
synoptic-convective dynamics, and orographic effects on spatiotemporal
details of the rainfall patterns.
Title: | Synoptic-dynamic analysis of early dry-season rainfall events in the Vietnamese Central Highlands |
Authors: | van der Linden, R. Fink, A.H. Phan-Van, T. Trinh-Tuan, L. |
Keywords: | Applications, Asia, Atm/ocean structure/phenomena, Atmospheric, Circulation/dynamics, Geographic location/entity, Monsoons, Rainfall, Regional effects, Tropics, Waves |
Issue Date: | 2016 |
Publisher: | American Meteorological Society |
Citation: | Scopus |
Abstract: | The Central Highlands are Vietnam's main coffee growing region. Unusual wet spells during the early dry season in November and December negatively affect two growing cycles in terms of yield and quality. The meteorological causes of wet spells in this region have not been thoroughly studied to date. Using daily rain gauge measurements at nine stations for the period 1981-2007 in the Central Highlands, four dynamically different early dry-season rainfall cases were investigated in depth: 1) the tail end of a cold front, 2) a tropical depression-type disturbance, 3) multiple tropical wave interactions, and 4) a cold surge with the Borneo vortex. Cases 1 and 4 are mainly extratropically forced. In case 1, moisture advection ahead of a dissipating cold front over the South China Sea led to high equivalent potential temperature in the southern highland where this air mass stalled and facilitated recurrent outbreaks of afternoon convection. In this case, the low-level northeasterly flow over the South China Sea was diverted around the southern highlands by relatively stable low layers. On the contrary, low-level flow was more orthogonal to the mountain barrier and high Froude numbers and concomitant low stability facilitated the westward extension of the rainfall zone across the mountain barrier in the other cases. In case 3, an eastward-traveling equatorial Kelvin wave might have been a factor in this westward extension, too. The results show a variety of interactions of large-scale wave forcings, synoptic-convective dynamics, and orographic effects on spatiotemporal details of the rainfall patterns. |
Description: | Monthly Weather Review Volume 144, Issue 4, 1 April 2016, Pages 1509-1527 |
URI: | http://journals.ametsoc.org/doi/10.1175/MWR-D-15-0265.1 http://repository.vnu.edu.vn/handle/VNU_123/34062 |
ISSN: | 00270644 |
Appears in Collections: | Bài báo của ĐHQGHN trong Scopus |
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