台风“麦德姆”福州降水δ18O特征及水汽来源分析

大气降水的氢氧同位素不仅在长时间尺度和短时间尺度上对气候环境有一定的响应,而且在极端天气事件中也响应强烈。论文基于2014年7月23—24日10号台风麦德姆登陆前后福州降水的氢氧稳定同位素分析,发现台风麦德姆降水的δ¹⁸O变化范围为-7.2‰~-15.4‰,整个降雨过程分为3个阶段：阶段1（23日3：00至23日12：00）,雨水δ¹⁸O相对偏正（加权平均值为-7.8‰）,降水开始增加,主要受台风外围环流的影响;阶段2（23日12：00至24日8：00）,雨水δ¹⁸O显著偏负（加权平均值为-13.9‰）,采样点降水量达134.8 mm,约占观测时段降水量的78%,降雨量效应明显,主要受台风云雨区影响;阶段3（24日8：00至24日17：00）,雨水δ¹⁸O偏正（加权平均值为-9.2‰）,降水减少,台风远离福州。通过降水δ¹⁸O的阶段性特征以及过量氘,结合水汽输送通量与HYSPLIT-4模拟水汽轨迹分析,确定此次降水的水汽源主要来自西北太平洋水汽通道与孟加拉湾和南海水汽通道。

The Analysis of the Characteristics and Water Vapor Source of the δ18O in the Precipitation of Typhoon “Matmo” at Fuzhou

Water vapor isotopes are not only controlled by the long-term and short-term conditions of climate, but are also very sensitive to extreme synoptic conditions. Hydrogen and oxygen isotopes in atmospheric precipitation not only have a certain response to climate change at different time scales, but also have strong linkages to extreme weather events. The study of precipitation isotopes was based on long and short term sampling in the past, but the study on the changes of the stable isotopes during the extreme precipitation and the source of water vapor is relatively less. This paper takes a typhoon rainfall as an example to reveal the changes of precipitation isotope and its effect mechanism in the typhoon weather. This study analyzed the precipitation and the stable isotopes during the period of No.10 Typhoon “Matmo” that landed Fuzhou in 2014. The range of δ¹⁸O in the “Matmo” precipitation is -7.2‰ - -15.4‰. The whole process of precipitation can be divided into three stages. At stage one (3:00 am July 23th to 12:00 am July 23th), the water vapor δ¹⁸O is relative heavy (weighted average value is -7.8‰). At this time, the external circulation of the typhoon influenced the sampling spot. At stage two (12:00 am July 23th to 8:00 am July 24th), the water vapor δ¹⁸O of sample spot become dramatically lighter (weighted average value is -13.9‰). The precipitation in this stage was 134.8 mm, which accounted for 78% of the precipitation in the observation period, and the effect of precipitation amount was obvious. At stage three (8:00 am July 24th to 17:00 pm July 24th), the typhoon precipitation δ¹⁸O become heavy again (weighted average value is -9.2‰）when the precipitation gradually decreased and the typhoon moved away from Fuzhou. The analysis of water vapor flux at 850 hPa and the HYSPLIT-4 simulations of vapor transport trajectories indicated that the water vapor source were primarily from the water vapor channel in the Northwest Pacific and the water vapor channel in the bay of Bengal and the South China Sea.