The focus of several past tropical cyclone (TC) studies in the Southwest Pacific (SWP) had been primarily at the regional scale, with little or no attention to the local-scale TC activity (i.e., at the country level). With the growing coastal population in the South Pacific Island countries, as well as increasing threats from and exposure to climate extremes mostly affecting vulnerable communities, examining TC-related risks at the country level is more imperative now than before. This study catalogues for the first time the climatology, variability and trends of TCs affecting Nuku'alofa, the capital of Tonga using the Southwest Pacific Enhanced Archived for Tropical Cyclone (SPEArTC) dataset for the period between 1970 and 2019. The variability is examined in relation to the El Niño–Southern Oscillation (ENSO) phenomenon, which is the major driver of the year-to-year variability of TC activity in the SWP. A total of 128 TC tracks affected the Tonga region over the study period, with a seasonal average of ∼2.6 TCs per year. Of these, about 50% occurred during the peak months of January and February, and ∼38.8% of the total were of hurricane intensity (Categories 3, 4 and 5). Although differences were found between the average number of TCs per year during El Niño, La Niña and ENSO-neutral events (∼2.9, ∼2.6 and ∼2.3, respectively), they were statistically insignificant. No significant long-term trends were found in the number of TCs, severe TCs, and accumulated cyclone energy (ACE) over the period of study. The findings of this study will provide the information needed for disaster preparedness and TC predictions in Tonga.

过去在西南太平洋 (SWP) 开展的几项热带气旋 (TC) 研究的重点主要集中在区域范围内，很少或根本没有关注当地规模的 TC 活动（即在国家层面）。随着南太平洋岛国沿海人口的不断增长，以及主要影响脆弱社区的极端气候威胁和暴露程度的增加，现在比以往更加迫切地需要在国家层面检查与 TC 相关的风险。本研究首次使用 1970 年至 2019 年期间的西南太平洋热带气旋增强存档 (SPEArTC) 数据集对影响汤加首都努库阿洛法的 TC 的气候学、变异性和趋势进行编目。变异性在与厄尔尼诺-南方涛动 (ENSO) 现象的关系，这是 SWP 中 TC 活动逐年变化的主要驱动因素。在研究期间，共有 128 个 TC 轨迹影响了汤加地区，季节性平均每年 2.6 个 TC。其中，约 50% 发生在 1 月和 2 月的高峰月份，其中约 38.8% 为飓风强度（3、4 和 5 类）。尽管在厄尔尼诺、拉尼娜和 ENSO 中性事件期间每年平均 TC 数量之间存在差异（分别为~2.9、~2.6 和~2.3），但它们在统计学上不显着。在研究期间，TC、严重 TC 和累积气旋能量 (ACE) 的数量没有发现显着的长期趋势。这项研究的结果将为汤加的备灾和 TC 预测提供所需的信息。