云南大气降水中δ18O与气象要素及水汽来源之间的关系

根据云南昆明、腾冲、蒙自三个地区在2009 年1 月至2011 年12 月3 a 间收集的大气降水以及相关气象要素资料，结合欧洲中期数值预报中心以及NCEP/NCAR提供的再分析资料，研究了天气尺度下三个地区大气降水中δ¹⁸O与降水量、温度、水汽压等气象要素之间的关系，并分析了δ¹⁸O与高空各气压层（800、700、500、300 hPa）风速的相关关系。结果表明：在天气尺度下，三个地区大气降水中δ¹⁸O与降水量、温度、水汽压均存在显著的负相关，表明三个地区大气降水中δ¹⁸O的变化具有显著的降水量效应、反温度效应以及湿度效应；同时，高空各气压层风速与δ¹⁸O之间存在正相关关系，表明高空风速也是影响大气降水中δ¹⁸O变化的一个重要因素。通过拉格朗日后向轨迹模型HYSPLIT 4.8 追踪三个地区水汽输送轨迹发现，三个地区大气降水的水汽来源基本一致，表明三地处在同一条水汽通道上。在湿季降水期间（5-9 月），水汽主要来源于孟加拉湾、阿拉伯海以及南海等海域，降水中δ¹⁸O偏低；而在干季降水期间（10 月-翌年4月），水汽主要来源于西风带携带的内陆水汽以及局地水汽再循环，降水中δ¹⁸O偏高。

Stable Oxygen Isotope in Precipitation in Relation to the Meteorological Factors and the Moisture Sources in Yunnan

Based on the data of precipitation samples and meteorological facters from Jan. 2009 to Dec. 2011 in Kunming, Tengchong and Mengzi of Yunnan Province. In combination with the data of the European Centre for Medium-range Weather Forecasts and the NCEP/NCAR, the relationships between the δ¹⁸O in precipitation and the precipitation amount, temperature and air pressure on the synoptic timescale were analyzed of the three stations. We also analyzed the relationships between the δ¹⁸O in precipitation and the wind speed of different heights. The results indicated that under the synoptic timescales, there was significant negative correlation between the δ¹⁸O in precipitation and the precipitation amount, temperature and air pressure. It suggested that the variations of the δ¹⁸O in precipitation had significant precipitation amount effect, anti-temperature effect and humidity effect. At the same time, there was significant positive correlation between the δ¹⁸O in precipitation and the different heights wind speed, this indicated that the wind speed of different heights was also an important factor in changing the δ¹⁸O in precipitation at some way. Taking advantage of the HYSPLIT 4.8 to track the trajectory of moisture sources in Kunming, Tengchong and Mengzi, we found that the moisture sources at the three stations were the same, the result indicated that the three stations were in the same water vapour channel. During the wet seasons (May-September), the moisture sources mainly came from the Bay of Bengal, the Arabin Sea and the South China Sea. However, the δ¹⁸O in precipitation during the wet seasons was lower. During the dry seasons (October-next April), the moisture sources maily came from westerly wind belt carried the inland water vapour and the local water vapour circulation. The δ¹⁸O in precipitation during the dry seasons was higher.