Journal of Tropical Oceanography >
Effect of environmental factors on the intensity of Typhoons Wutip and Mirinae in the South China Sea
Received date: 2017-06-27
Request revised date: 2017-09-26
Online published: 2018-05-03
Supported by
Haiyan Project of Shanghai Ocean University (A2-0203-00-100520)
Research Business Expenses of College of Marine Sciences in Shanghai Ocean University (D-8002-15-8003)
Basic Research Business Expenses of Guangxi Academy of Sciences (13YJ22HY07)
Copyright
We selected two rapidly intensifying, locally-originated typhoons Wutip (1321) and Mirinae (1603), and analyzed upper- and low-level circulations, vertical wind shear, and ocean heat content in and around the South China Sea during typhoons’ passages over the sea. We also used WRF (Weather Research and Forecasting Model) model to discuss the environmental factors for their different intensities. Although the underlying conditions were more favorable for Mirinae, it did not develop into a strong typhoon due to weak upper- and low-level circulations and strong vertical wind shear. On the contrary, Wutip developed into a super typhoon rapidly due to the cold southward airflow and the outburst of warm humid air from the southwest. The results from WRF model’s sensitivity experiments about the effect of sea surface temperature (SST) on the intensity of locally-originated typhoon indicated that locally-originated typhoon intensity and SST have nonlinear positive correlation. However, as SST increases, the intensification trend of locally-originated typhoon slows down. From July to September, the SST in the South China Sea is higher than 28℃, meeting the condition for typhoon intensification. Therefore, attention should be paid to different environmental factors other than SST in locally-originated typhoons’ forecast in the South China Sea.
WU Haoliang , HU Song . Effect of environmental factors on the intensity of Typhoons Wutip and Mirinae in the South China Sea[J]. Journal of Tropical Oceanography, 2018 , 37(3) : 26 -34 . DOI: 10.11978/2017073
Fig. 1 The tracks of “Wutip” (1321) and “Mirinae” (1603)图1 “蝴蝶”(1321)与“银河”(1603)路径图 |
Fig. 2 Temperature on 850 hPa (shading; units: ℃) and isoheight on 500 hPa (units: m) in the South China Sea and its surroundings. Wutip: a) 00UTC Sep. 29, b) 06UTC Sep. 30; Mirinae: c) 12UTC Jul. 26, d) 12UTC Jul. 27. No data for the Tibetan Plateau图2 南海及周边850hPa气温(填色)与500hPa等高线(单位: m)图 |
Fig. 3 Circulation on 200 hPa in the South China Sea and its surroundings. a) Wutip at 00UTC Sep. 29; b) Mirinae at 12UTC Jul. 26图3 南海及周边200hPa高空流场图 |
Fig. 4 Vertical wind shear in the South China Sea and its surroundings. a) Wutip at 00UTC Sep. 29; b) Mirinae at 12UTC Jul. 26. Black star denotes TC center图4 南海及周边垂直风切变分布图 |
Fig. 5 SST in the South China Sea. a) Wutip on Sep. 2013; b) Mirinae on Jul. 2016图5 南海SST分布图 |
Tab. 1 Four numerical experiments表1 不同数值试验方案 |
实验 | SST设置 | 实验设置 |
---|---|---|
EXP1 | 关闭 | FNL海温场不随时间变化(过程不变) |
EXP2 | 打开 | FNL自带海温场每6h变化(过程变化) |
EXP3 | 打开 | FNL自带海温场降低1℃每6h变化(过程变化) |
EXP4 | 打开 | FNL自带海温场升高1℃每6h变化(过程变化) |
Fig. 6 WRF domain and comparison of tracks between CMA and simulation. The blue line denotes Wutip track, red line denotes Mirinae track, and light blue stars denote simulated results图6 WRF网格与土台风模拟路径对比 |
Fig. 7 SST experiment results of Wutip (a, b) and Mirinae (c, d)图7 “蝴蝶”(a、b)与“银河”(c、d)3组实验随模式积分时间变化图 |
Fig. 8 Moisture mixing ratio of Wutip (a) and Mirinae (b)图8 “蝴蝶”(a)和“银河”(b)大气底层水汽混合比展开图 |
Fig. 9 Background wind field on 850 hPa in the South China Sea and its surroundings. a) Wutip at 00UTC Sep. 29; b) Mirinae at 12UTC Jul. 26. No data on the Tibetan Plateau图9 南海及周边850hPa背景风场 |
The authors have declared that no competing interests exist.
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