Modulation of low-latitude west wind on abnormal track and intensity of tropical cyclone Nargis (2008) in the Bay of Bengal |
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Authors: | LI Wei-Wei WANG Chunzai WANG Dongxiao YANG Lei DENG Yi |
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Institution: | State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology,Chinese Academy of Science, Guangzhou 510301,NOAA/Atlantic Oceanographic and Meteorological Laboratory, Miami, Florida, USA,State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology,Chinese Academy of Science, Guangzhou 510301,State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology,Chinese Academy of Science, Guangzhou 510301,State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510301 |
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Abstract: | Tropical cyclone (TC) Nargis (2008) made landfall in Myanmar on 02 May 2008,
bringing a storm surge, major flooding, and resulting in a significant death
toll. TC Nargis (2008) displayed abnormal features, including rare eastward
motion in its late stage, rapid intensification before landing. Using
reanalysis data and a numerical model, we investigated how a low-latitude
westerly wind modulated TC Nargis' (2008) track and provided favorable
atmospheric conditions for its rapid intensification. More importantly, we
found a possible counterbalance effect of flows from the two hemispheres on
the TC track in the Bay of Bengal. Our analysis indicates that a strong
westerly wind burst across the Bay of Bengal, resulting in TC Nargis' (2008)
eastward movement after its recurvature. This sudden enhancement of westerly
wind was mainly due to the rapidly intensified mid-level cross-equatorial
flow. Our results show that a high-pressure system in the Southern
Hemisphere induced this strong, mid-level, cross-equatorial flow. During the
rapid intensification period of TC Nargis (2008), this strong and broad
westerly wind also transported a large amount of water vapor to TC Nargis
(2008). Sufficient water vapor gave rise to continuously high and increased
mid-level relative humidity, which was favorable to TC Nargis' (2008)
intensification. Condensation of water vapor increased the energy supply,
which eventuated the intensification of TC Nargis (2008) to a category 4 on
the Saffir-Simpson scale. |
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Keywords: | TC Nargis (2008) tropical cyclone westerly wind cross-equatorial flow Bay of Bengal |
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