Different effects of tropical cyclones generated in the South China Sea and the northwest Pacific on the summer South China Sea circulation

In addition to tropical cyclones (TCs) locally formed in the South China Sea (SCS), there are also TCs that initially form over the Northwest Pacific (NWP) and move westward to enter the SCS (often called nonlocal TCs). It is unclear how those nonlocal TCs are modulated by the intraseasonal climate variability. In this study, the impacts of two types of intraseasonal oscillations, namely the Madden–Julian Oscillation (MJO) and the quasi-biweekly oscillation (QBWO), on nonlocally formed TCs over the SCS in summer (May–September) are analyzed based on best-track TC data and global reanalysis during 1979–2018. Results show that in the convective phases of both MJO and QBWO, the western Pacific subtropical high shifted more eastward, and more TCs entered the SCS. This is mainly because more TCs formed in the NWP in the convective phases of intraseasonal oscillations and the genesis locations of the NWP TCs shifted westward and closer to the SCS. In addition to TC count, intraseasonal oscillations also affected the intensity of nonlocal TCs entered the SCS, with the influence of QBWO being more significant than MJO. In the convectively active phases of QBWO (phases 2–5), 34 nonlocal TCs reached typhoon intensity, while only two nonlocal TCs reached typhoon intensity in the convectively inactive phases (phases 1, 6, 7, 8). Further analysis indicates that nonlocal TCs often moved with the northwestward propagating convective signals of QBWO, resulting in more and stronger TCs that entered the SCS in the convective phases of QBWO. The mean location that the nonlocal TC entered the SCS also shifted northward with the northward propagation of intraseasonal oscillations.

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Temporal-spatial characteristics and path analysis of maritime cyclones in Guangdong coastal areas in the South China Sea

Earth Sciences Research Journal ◽

10.15446/esrj.v22n4.77361 ◽

2018 ◽

Vol 22 (4) ◽

pp. 319-325

Author(s):

Cheng Chen ◽

Lei Wang ◽

Ruozhou Chen ◽

Fangliang Xing ◽

Jun Chen

Keyword(s):

South China Sea ◽

Tropical Cyclones ◽

South China ◽

The South China Sea ◽

Northwest Pacific ◽

The South ◽

The West ◽

Spatial Characteristics ◽

China Sea ◽

Path Direction

This study was conducted to analyze the maritime cyclone characteristics in Guangdong coast in the years of 1949 to 2016, including inter-annual variation, the intensity of tropical cyclones, generating location and time, and path direction. The temporal-spatial characteristics were also studied. Results show there were 183 tropical cyclones landed in Guangdong coast in the past 68 years, with an average of 2.7 each year, which more than 60 percent were a typhoon. Most of the tropical cyclones were generated in the northwest Pacific, spanning from April to December. The path directions were mainly north, northwest, and west. The strengths of the tropical cyclones were reduced from central Guangdong coast to the east and the west sides, and the section of Zhanjiang city to Shenzhen city was the most vulnerable to tropical cyclones. Tropical cyclones that generated in the South China Sea tend to attack the west of the Guangdong coast, while the ones that produced in the northwest Pacific tend to attack the east of the Guangdong coast. In the study area, the tropical cyclones frequently occurred from July to September and became strongest in September. There are a most common landing section and path direction for each month. Finally, based on the statistical data and research results, the tropical cyclone paths in Guangdong coast were preliminarily analyzed.

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