ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
The Influence of Quasi-biweekly Oscillations on Continuous Warm-sector Rainstorm in Guangdong in June 2023
- Article
- Figures
- Metrics
- Preview PDF
- Reference
- Related
- Cited by
- Materials
Abstract:
The low-frequency oscillation characteristics of continuous rainstorm processes in Guangdong during the first rainy season in 2023 were analyzed by the methods of wavelet analysis and Lanczos temporal filter, focusing on revealing the mean atmospheric circulation field and it’s evolution characteristics in different phases of quasi-biweekly oscillations and the source of the low-frequency signals of the continuous warm-sector rainstorms with strong southwesterlies in the northwest of Guangdong. The results show that the three continuous rainstorm exhibited a quasi-7-18-day periodic oscillation, and they are in the positive phase of two quasi-30-60-day intraseasonal oscillations. The continuous warm-sector rainstorms with strong southwesterlies that occurred in the northwest of Guangdong on 22-26 June, there were stable“west blocking”and“east blocking” at the middle and high latitudes, the northwest of Guangdong was located at the bottom of the plateau trough and the edge of the subtropical high at 500 hPa, and at the left side of southwest wind axis and the right side of the cyclonic circulations at 850 hPa. During the intermittent- start-peak period of the continuous warm-sector rainstorms process with strong southwesterlies , the low-frequency signals in the mid-to-upper levels originate from the southern branch wave train with the eastward propagation and southward extension of baroclinic low-frequency anticyclones and cyclones within or south of the Iranian Plateau-Tibetan Plateau，and the low-frequency signals in the lower levels arise from the eastward movement and southward extension of the Mongolian Plateau low-frequency anticyclone and the progressively intensifying low-frequency cyclone east of the Sichuan Basin and Yunnan-Guizhou Plateau. They inducing the center of South Asian High to gradually move eastward, the western Pacific subtropical high to weaken and retreat eastward, the Qinghai-Tibet Plateau is controlled by low-frequency cyclonic circulation in intermittent periods gradually turning into the low-frequency anticyclone circulation in the peak period，and the North China - South China region is controlled by low-frequency anticyclone circulation in intermittent periods gradually turning into the low-frequency cyclonic circulation in the peak period. They can provide a reference for medium-to-extended range forecasting of continuous warm-sector rainstorm.
Keywords:
Project Supported:
Clc Number:
Mobile website
