Rainy Season of the Asian–Pacific Summer Monsoon*

Abstract

To date, the monsoon-research community has not yet reached a consensus on a unified definition of monsoon rainy season or on the linkage between the onsets over the Asian continent and the adjacent oceans. A single rainfall parameter is proposed, and a suite of universal criteria for defining the domain, onset, peak, and withdrawal of the rainy season are developed. These results reveal a cohesive spatial-temporal structure of the Asian-Pacific monsoon rainy season characteristics, which will facilitate validation of monsoon hydrological cycles simulated by climate system models and improve our understanding of monsoon dynamics. The large-scale onset of the Asian monsoon rainy season consists of two phases. The first phase begins with the rainfall surges over the South China Sea (SCS) in mid-May, which establishes a planetary-scale monsoon rainband extending from the south Asian marginal seas (the Arabian Sea, the Bay of Bengal, and the SCS) to the subtropical western North Pacific (WNP). The rainband then advances northwestward, initiating the continental Indian rainy season, the Chinese mei-yu, and the Japanese baiu in early to mid-June (the second phase). The heights of the rainy seasons occur primarily in three stepwise phases: in late June over the mei-yu/baiu regions, the northern Bay of Bengal, and the vicinity of the Philippines, in late July over India and northern China; and in mid-August over the tropical WNP. The rainy season retreats northward over east Asia, yet it moves southward over India and the WNP. Clear distinctions in the characteristics of the rainy season exist among the Indian, east Asian, and WNP summer monsoon regions. Nevertheless, the rainy seasons of the three subsystems also show close linkage. The causes of the regional distinctions and linkages are discussed. Also discussed are the atypical monsoon rainy seasons, such as the skewed and bimodal seasonal distributions found in various places of Asian monsoon domain.

Seasonal forecasting of East Asian summer monsoon based on oceanic heat sources

“…The EASM is normally referred to as a subtropical monsoon covering eastern China, the Korean peninsula, Japan, and adjacent marginal seas (e.g., Zhang et al, 1996;Wang and Lin, 2002;Wu and Wang, 2002;Wang and Li, 2004). The region of the EASM in this study is 20°∼ 50°N and 110°∼ 145°E, divided into the NEASM and SEASM regions (Figure 1(a)).…”

Rainfall intensity–duration conditions for mass movements in Taiwan

“…1). Taiwan experiences tropical and subtropical-monsoon climates, with the boundary between the two climate regimes located in southern Taiwan (Wang and Ho 2002). The average temperature over the Taiwanese lowlands during the wet season (May-October) is above 20°C, while the average temperature during the dry season (November-April) is between 14 and 20°C.…”

Impacts of Re-greening the Desertified Lands in Northwestern China: Implications from a Regional Climate Model Experiment

“…This seasonal rain belt becomes somewhat stationary over South China, the Yangtze-Huaihe River Basin and North China, respectively, during its two notable northward jumps (Ding and Liu 2001). When the monsoon rainband reaches the Yangtze-Huaihe River Basin in the first half of June, it marks the beginning of the so-called Mei-Yu season in China (Wang and LinHo 2002). The Mei-Yu season, which peaks in late June, is characterized by persistent and torrential rainfall associated with the quasistationary Mei-Yu front.…”