Open AccessInterannual Variation of the Late Fall Rainfall in Central Vietnam
Author(s) -
Tsing Chang Chen,
JenqDar Tsay,
Ming Cheng Yen,
Jun Matsumoto
Publication year - 2012
Publication title -
journal of climate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.315
H-Index - 287
eISSN - 1520-0442
pISSN - 0894-8755
DOI - 10.1175/jcli-d-11-00068.1
Subject(s) - climatology , tropical cyclone , tropical cyclone rainfall forecasting , precipitation , environmental science , westerlies , flood myth , cyclone (programming language) , sea surface temperature , atmospheric sciences , geology , geography , meteorology , archaeology , field programmable gate array , computer science , computer hardware
The heavy rainfall/flood (HRF) event in central Vietnam usually occurs in October–November, the maximum rainfall season. This rainfall maximum undergoes a distinct interannual variation, opposite the interannual variation of sea surface temperature (SST) anomalies averaged over the NOAA Niño-3.4 area—ΔSST(Niño-3.4)—but coincident with the intensification (weakening) of the low-level easterlies at 15°N and westerlies at 5°N. The changes of low-level zonal winds reflect the strengthening (weakening) of the tropical cyclonic shear flow in tropical South/Southeast Asia in response to the tropical Pacific SST anomalies. Because the rainfall maximum in central Vietnam is primarily produced by the HRF cyclone, the interannual rainfall variation in this region should be attributed to the HRF cyclone activity—a new perspective of the climate change in precipitation. On average, one HRF cyclone occurs in each cold late fall. The population of the HRF cyclone may not be an important factor causing the interannual rainfall variation in central Vietnam. During the cold late fall, the rain-producing efficiency of the individual HRF cyclone is statistically almost twice those during warm and normal late falls and the most crucial factor leading to the interannual rainfall variation in central Vietnam. It is shown by further hydrological analysis that the increase (decrease) of the HRF cyclone’s rain-producing efficiency is determined by the large-scale environmental flow through the enhancement (weakening) of the regional convergence of water vapor flux.