The Influence of Tropical Cyclone Characteristics on Rainstorm Magnitude in Beijing

Due to climate change, the quantity of extreme rainfall events caused by tropical cyclones in Beijing have exhibited a significant increasing trend, posing great challenge to disaster prevention and mitigation efforts in the city. To enhance Beijing's capacity to respond to tropical cyclone-induced precipitation, this study collects multi-source data on precipitation, tropical cyclones, and precipitable water vapor. It proposes a dual-scale (temporal and spatial) quantitative identification method for tropical cyclone precipitation, generates a tropical cyclone precipitation dataset for Beijing, and compiles a dataset of 20 typical tropical cyclones. Furthermore, the study elucidates the characteristics of tropical cyclones affecting Beijing. 24 indicators reflecting the characteristics of tropical cyclone were designed based on the how tropical cyclone forms rainfall. A quantitative study on the relationship between the characteristics of tropical cyclones and the precipitation characteristics in Beijing, (i.e. the total rainfall and the maximum 1-day rainfall) was conducted. The results indicates that: 1) A increasing trend was observed in the number of tropical cyclones impacting Beijing from the 1980s to the 2010s, with indications that this trend is likely to continue. Furthermore, statistical analysis confirms that tropical cyclones making landfall in Shandong and Liaoning provinces are more likely to trigger extreme rainfall events in Beijing; 2) the correlation between the total precipitation of the tropical cyclone and the distance from the tropical cyclone centre to the centroid of Beijing shows a trigonometric distribution, and the total precipitation generally reaches to maximum at the distance of 500 km, and to minimum at the distance of 400 and 700km; 3) the maximum 1-day precipitation of the tropical cyclone and the precipitable water vapor show a significant positive correlation which is affected by the distance from the tropical cyclone centre to the centroid of Beijing; specifically, the correlation coefficient up to 0.95 when the distance is less than 500km, whereas it decreases to 0.56 when the distance exceeds 500km; 4) Regression models were constructed to quantify the relationships between the 24 characteristic indicators and the precipitation characteristics in Beijing (i.e. the total rainfall and the maximum 1-day rainfall). The models demonstrated a strong goodness-of-fit, with Pearson correlation coefficients reaching 0.90 for total rainfall and 0.83 for maximum 1-day rainfall.