常昕^1,,
章新平^1,2,,,
戴军杰¹,
刘仲藜¹
1. 湖南师范大学资源与环境科学学院, 湖南 长沙 410081
2. 湖南师范大学地理空间大数据挖掘与应用湖南省重点实验室, 湖南 长沙 410081

基金项目: 国家自然科学基金项目（批准号：41571021）和湖南师范大学2020年大型仪器测试开放基金（批准号：2020192）共同资助


详细信息

作者简介: 常昕, 女, 23岁, 硕士研究生, 自然地理学专业, E-mail:870355137@qq.com

通讯作者: 章新平, E-mail:zxp@hunnu.edu.cn

中图分类号: P426.6

收稿日期:2020-06-29
修回日期:2020-10-21
刊出日期:2021-01-30

Comparison of stable isotope effects under different time scales: Taking Changsha as an example

CHANG Xin^1,,
ZHANG Xinping^1,2,,,
DAI Junjie¹,
LIU Zhongli¹
1. College of Resources and Environmental Sciences, Hunan Normal University, Changsha 410081, Hunan
2. Key Laboratory of Geospatial Big Data Mining and Application, Changsha 410081, Hunan


More Information

Corresponding author: ZHANG Xinping,E-mail:zxp@hunnu.edu.cn

MSC: P426.6

--> Received Date: 29 June 2020
Revised Date: 21 October 2020
Publish Date: 30 January 2021


摘要
摘要:基于长沙2010年1月~2019年12月日降水中氢、氧稳定同位素以及相应日平均温度和日降水量的监测数据，利用数理统计方法对该站在日、月、年三类时间尺度下以及在不同降水强度条件下的降水中δ¹⁸O与降水量、δ¹⁸O与温度之间的关系以及局地大气水线（LMWL）变化特征进行分析和比较，其目的在于揭示在不同时间尺度下和不同降水强度条件下降水中稳定同位素效应的差异，深化对季风区降水稳定同位素变化规律的认识。结果表明：在长沙，降水中δ¹⁸O的变化范围随时间尺度的增大而减小；在日时间尺度下，降水量效应稳定存在，受雨滴下降过程中蒸发富集的影响，5.0 mm/d以下的小降水事件明显改变δ¹⁸O-P回归线的斜率。在月和年时间尺度下，降水中稳定同位素均不存在显著的降水量效应；在雨热同期的气候背景下，除冷半年外，在日和月时间尺度下，降水中δ¹⁸O与温度均存在显著的负相关关系。在年时间尺度下，降水中年加权平均δ¹⁸O与温度之间不存在显著的相关关系；对应于不同的时间尺度、不同的季节和不同的降水强度，LMWL均具有显著的差异。在日和月的时间尺度下，冷半年LMWL的斜率和截距分别小于和大于暖半年LMWL的斜率和截距，且随降水强度的增加呈先明显增加（日时间尺度在5.0 mm/d以下，月时间尺度在50.0 mm/month以下）、然后保持基本不变的态势。在年时间尺度下，冷半年LMWL的斜率和截距均大于暖半年。
关键词: 大气降水/
稳定同位素效应/
不同时间尺度/
比较

Abstract:The study area, Changsha, is located in the East China(27°53'~28°41'N, 111°53'~114°15'E). The climate of the study area is mild and humid, with four discernable seasons and rain and heat changing synchronically, categoried into the typical sub-tropical monsoon climate. Due to locating in the intersection of the southwest monsoon, the southeast monsoon and the westerlies, the complex process of precipitation formation under different weather or seasons, and the complicated variation characteristics of precipitation stable isotopes composition, Changsha is a prefect site to investigate the characteristics and influence mechanism of stable isotopes in precipitation in monsoon region. From January 2010 to December 2019, the precipitation samples were collected at the meteorological station of Hunan Normal University at the foot of Yuelu Mountain in Changsha. The whole sampling period consists of 10 complete natural years, with a total of 1247 daily precipitation samples collected, representing 1247 precipitation days. All water samples were analyzed using a Cavity Ring-Down Spectroscopy(CRDS) Isotopic Water Analyzer(Model 35EP, Los Gatos Research, Inc., USA) at the Meteorological and Climatic Laboratory of Hunan Normal University. Based on the observation data of stable isotopic composition(²H and ¹⁸O) in precipitation and the corresponding daily mean temperature and precipitation for ten years, the relationship between δ¹⁸O and precipitation(temperature) and the variations of local meteoric water line(LMWL) were analyzed and compared through primary statistics methods under daily, monthly and annual time scales with different precipitation intensities. Our aims were either to reveal the differences of the stable isotope effects in different precipitation intensities and time scales or to enhance the understanding of the variations regularity of the stable isotopes in precipitation within the monsoon region. The results showed that the variation range of precipitation δ¹⁸O reduced with lengthening time scale in Changsha. Under the daily time scale, the amount effect was pronounced. Affected by the evaporation enrichment during the falling of raindrops, the weak rainfall events(< 5 mm/d) influenced the regression slope of δ¹⁸O-P obviously. Under the monthly and annual time scales, there was no obvious amount effect in precipitation isotopes. Under the climatic background characterized by synchrony of abundant rainfall and high temperature, a significant negative correlation was observed between precipitation δ¹⁸O and temperature under both daily and monthly time scales except cold half-year. Under the annual time scale, there was no obvious correlation between the precipitation δ¹⁸O with weighted averaged precipitation and the mean temperature. LMWL was obviously different under different time scales, seasons and precipitation intensities. Under the daily and monthly time scales, the slope and interception of the LMWL in the cold half-year were obviously smaller and larger than those in the warm half-year respectively, and they increased obviously with the increase of precipitation intensity and then remained less variable when daily and monthly precipitation intensity was less than 5 mm/d and 50 mm/mon, respectively. Under the annual time scale, the slope and interception of the LMWL in the cold half-year were larger than those in the warm half-year.
Key words:atmospheric precipitation/
stable isotope effect/
different time scales/
comparison



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