Large-scale atmospheric features favoring the tropical cyclone activity affecting the Guangdong–Hong Kong–Macao Greater Bay Area of China

Abstract

This study analyzes the large-scale circulation associated with the tropical cyclones (TCs) affecting the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) in southern China during the peak TC season (July–September) from 1980 to 2019. The results show that the frequency of the TCs affecting the GBA is closely tied to a meridional Rossby wave train from Southeast Asia to Northeast Asia, manifested by the important roles of the variability of the monsoon trough (MT) and the western North Pacific subtropical high (WNPSH). In the active GBA TC years, intensified and westward-shifted MT and northeastward-shrunk WNPSH cause anomalous southeasterly wind over the southeast coast of China, and hence more TCs move northwestward to the GBA. Furthermore, the cyclonic convergent conditions related to the tacit-and-mutual configurations of MT and WNPSH favor more TC genesis in the west of 140°E over the WNP via significant larger meridional shear vorticity of the zonal winds, ascending motions, and positive vorticity. Opposite features of wind anomalies and TC genesis are seen in the inactive GBA TC years. Both statistical and numerical analyses confirm that the meridional Rossby wave train is associated with a Matsuno–Gill response to the anomalous convective activity over the western Pacific warm pool, which is maintained by the ascending branches of the La Niña-type Walker circulation over the Pacific and the monsoon-enhanced Walker circulation over the Indian Ocean.

Impact of Thermal Forcing over the Southeast of the Tibetan Plateau on Frequency of Tropical Cyclones Affecting Guangxi during Boreal Summer

“…According to a previous work [6], steering flow (SF) is represented by the pressureweighted wind averaged from 850 hPa to 300 hPa. The Diabatic heating (Q1) is calculated based on the thermodynamic equation [32].…”

“…Figure 3c shows that a Additionally, the atmospheric circulation anomalies may affect the genesis of the Guangxi TCs formed within the west of 120 • E. In comparison, the TCs affecting Guangxi formed within the west of 120 • E are more likely to form over the north of 15 • N during the negative RSTP years (Figure 3a,b). Following previous studies [6,33], TC genesis-related environmental conditions are further examined. The composite differences DGPI between the negative and positive RSTP years are shown in Figure 4a-e.…”

“…Previous studies have suggested that landfalling tropical cyclones in southern China are generated over the Philippine Sea and the South China Sea (SCS) and then gradually move northwest toward the southern coast. These tropical cyclones can be tracked along the southwestern edge of the western North Pacific subtropical high [5][6][7]. In particular, the frequency of landfalling typhoons in southern China has increased since the year 2000 [8][9][10].…”

Research on Typhoon Multi-Stage Cloud Characteristics Based on Deep Learning

“…They not only pose a great threat to the normal production and the life of coastal residents but also exert an important impact on the regional climate and environment. This is an important natural weather system [48,49]. Studying the activity and variation characteristics of typhoons is of great significance not only for society but also in the context of science.…”

Regime Shifts in the Damage Caused by Tropical Cyclones in the Guangdong–Hong Kong–Macao Greater Bay Area of China

“…These parameters constantly affected by environmental factors such as sea surface temperature (SST), subtropical high, atmosphere vertical velocity, relative humidity and vertical wind shear [3][4][5][6][7][8][9]. These environmental factors are always regulated by climatic signals, e.g., El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation 2 of 17 (PDO) and Indian Ocean Dipole (IOD) [10][11][12][13][14]. Limited research has been conducted on the annual TC size, highlighting the significant influence of TC intensity in regulating TC size.…”