This study investigated rainfall trends and their associations with tropical cyclones (TCs) during the period of 1979-2019, using TC best-track data from the Regional Specialized Meteorological Center Tokyo - Typhoon Center and daily rainfall data from 138 meteorological stations in Vietnam. The radius of influence of TCs on local rainfall was limited to 500 km from TC centers. The average annual number of TCs affecting Vietnam has decreased slightly in the last two decades compared to previous decades. The ratio of TC-induced rainfall to total rainfall attained the highest value of 37.3% in the central region, in July. The temporal distribution of TC-induced rainfall coincided with the frequency of TCs, with an active period from June to November. During 1979-2019, the non-TC rainfall was the main contributor to the change in total rainfall, especially in relation to the decline in the north and the increase in the coastal South Central region. The rainfall trend during the entire period was principally explained by the interdecadal shift in the late 1990s. Rainfall intensity and the number of heavy rainfall days were intensified for total rainfall and non-TC rainfall, indicating that TCs contributed minimally to the changes of extreme rainfall events during 1979-2019.

这项研究使用东京地区专业气象中心-台风中心的TC最佳跟踪数据和越南138个气象站的每日降雨数据，调查了1979-2019年期间的降雨趋势及其与热带气旋的关系。TC对当地降雨的影响半径限制在距TC中心500公里处。与过去几十年相比，过去二十年来，影响越南的TC的年均数量略有下降。7月，中部地区TC引起的降雨与总降雨之比达到最高值37.3％。TC引起的降雨的时间分布与TC的频率一致，活动期为6月至11月。1979-2019年间，非热带雨水是造成总雨量变化的主要因素，特别是在北部地区的减少和沿海中南部地区的增加方面。整个时期的降雨趋势主要是由1990年代后期的年代际变化解释的。总降雨量和非TC降雨量的降雨强度和强降雨天数都增加了，这表明TC对1979-2019年极端降雨事件变化的贡献最小。