| 摘要: |
| 基于2018年第8号台风“玛莉亚”登陆前后福州、将乐两地小时分辨率的降水同位素数据，结合气象资料，分析了此次台风期间两地的降水δ18O变化特征及影响因素。台风“玛莉亚”影响期间，福州降水δ18O值变化范围为−2.72‰—−10.52‰，振幅达7.8‰，平均值为−8.42‰，呈现倒U型的三阶段变化特征，阶段1、3降水δ18O值相对偏正，受蒸发效应影响显著；阶段2降水δ18O值显著偏负，平均值为−8.95‰，远低于福州夏季多年降水δ18O平均值−6.53‰。将乐降水δ18O值变化范围为−1.70‰—−11.93‰，振幅为10.23‰，平均值为−10.06‰，呈现“厂”字型的两阶段变化特征，阶段1降水δ18O值相对偏正，变化范围为−1.70‰—−7.54‰；阶段2降水δ18O值显著偏负，平均值为−10.66‰。台风期间，两地阶段2的降水δ18O值受“云雨区效应”的影响显著偏负。随着台风登陆并向内陆移动，受同位素瑞利分馏及地形的影响，内陆将乐δ18O值进一步偏负。水汽输送通量分析表明，此次台风影响期间水汽主要来源于西北太平洋、印度洋和南海通道。 |
| 关键词: 台风“玛莉亚” 降水 稳定同位素 水汽源 云雨区效应 |
| DOI：10.7515/JEE202013 |
| CSTR： |
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| 基金项目:国家自然科学基金项目（41672170） |
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| The characteristics and influence factors typhoon “Maria” induced rainfall δ18O at Fuzhou and Jiangle |
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CAI Jianrong, XU Tao, Yang Yunyue, JIANG Xiuyang
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1. Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
2. School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China
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| Abstract: |
| Background, aim, and scope Hydrogen and oxygen stable isotopes in atmospheric precipitation are often used in hydrological cycles and paleoclimatic reconstruction studies for their high sensibility to environmental changes. Typhoon precipitation has a large contribution rate to precipitation in southeastern China. However, the influence of typhoons often lasts only 1 to 2 days, and the existing monthly and daily precipitation data are not suitable for in-depth study of the internal variation characteristics of stable isotopes of typhoon precipitation. In addition, when the typhoon landed on the southeast coast and moved inland, with the weakening of the typhoon energy, the precipitation weakened and mixed with local water vapor, making the inland precipitation δ18O more complicated. Based on the meteorological data and stable isotope compositions in precipitation of No.8 typhoon “Maria” at Fuzhou and Jiangle, the characteristics of stable isotope compositions in precipitation of typhoon “Maria” and its influence factors have been analyzed. This has important implications for understanding the mechanism of typhoon impact on regional rainfall stable isotopes. Materials and methods Based on the meteorological data and stable isotope compositions in precipitation of No.8 typhoon “Maria” in 2018 at Fuzhou and Jiangle, combined with the HYSPLIT model to simulate the source trajectory of water vapor, the mechanism of the influence of typhoon movement on the stable isotope of regional precipitation is explored. Results The results show that: (1) the local meteoric water line, established as: δ2H=7.30δ18O−3.51 (R2=0.95, N=13, Fuzhou); δ2H=6.93δ18O−4.37 (R2=0.99, N=17, Jiangle). (2) During the period of typhoon “Maria”, the variation of precipitation δ18O in Fuzhou is characterized by three stages, which exhibiting a reversed U-shaped pattern. The precipitation δ18O in stage one and three are relative positive, while in the second stage is relative negative which is far below the average value of summer precipitation δ18O in Fuzhou (−6.53‰). (3) The variation of precipitation δ18O in Jiangle is characterized by two stages, which are similar to Chinese character “chang”. The precipitation δ18O in the stage one of Jiangle is relative positive, while the precipitation δ18O in stage two of Jiangle is relative negative. Discussion (1) The local meteoric water line (MLY-Fuzhou, MLY-Jiangle) had a lower slope and intercept than GMWL and LMWL which indicated that the stable isotopes composition in typhoon precipitation at Fuzhou and Jiangle are affected by strong “evaporation effect”. (2) The stable isotope composition of stage two precipitation which has the most negative values is mainly influenced by “rain shield effect” with large-scale convection, high condensation efficiency, and isotopically depleted recycling. (3) Through the study of typhoon precipitation δ18O, typhoon precipitation δ18O has the characteristics of spatial variation. As the typhoon landed and moved inland, affected by Rayleigh fractionation, the inland δ18O value was further negative. However, due to the fact that the terrain of Fujian is high in the west and low in the east, the change of terrain factors must also be considered. Conclusions The extreme negative of the δ18O value of precipitation in stage two is affected by “rain shield effect”. As the typhoon landed and moved inland, the inland δ18O value became further negative, which is the result of the combined effect of Rayleigh fractionation and terrain. During the impact of the typhoon, water vapor mainly originated from the Northwest Pacific, Indian Ocean and South China Sea channels. Recommendations and perspectives This study is based on the Fuzhou and Jiangle sites to study the impact of typhoon precipitation on the local precipitation δ18O. If more sampling points can be added for a more comprehensive comparison study, then more accurate conclusions can be drawn. |
| Key words: typhoon “Maria” precipitation stable isotope ratios rain shield effect terrain |
