As home to about 70 million people, the Mekong River Basin (MRB), located in Mainland Southeast Asia, is often influenced by tropical cyclones (TCs) landfalling. The TCs not only cause flood and storm hazards, but also play important roles in providing freshwater resource and welcomed sediment transports. Our study focuses on the climatology of TCs and associated rainfall (TCR) in the MRB for 1983–2016. Results show that: (i) the mean landfall occurrence of TCs is 6.2 yr−1, leading to 36.7 mm yr−1 of annual mean TCR (2.5% of the annual total precipitation), which mainly occur in monsoon-TC season (i.e., June–November); (ii) TCs highly concentrate on the lower eastern MRB, generating the largest TCR contribution of 12.4% to the annual total precipitation; (iii) the annual mean contribution of TCs induced extreme precipitation - R20mm and R50mm (days of heavy precipitation rate ≥20 mm day−1 and ≥50 mm day−1, respectively) - to that from annual total precipitation is large in the lower eastern MRB; (iv) over 60% of the basin area is influenced by TCR on average; and (v) a significant weakening trend of the TC frequency has been observed. The present findings lay a foundation for further in-depth research of the potential influence of the dynamic TCs and the associated rainfall in the MRB.

This research was supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20060401); the China Scholarship Council; the National Natural Science Foundation of China (Grant No. 91537210); Swedish STINT (Grant No. CH2015–6226); the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement (Grant No. 703733); and the Swedish VR (Grant No. 2017-03780).