Research Of Indication Of Oxygen And Hydrogen Isotopic Characteristics Of Precipitation In Shanghai For ENSO Events

ENSO is a global atmosphere circulation anomalies event which induces abnormal weather and climate events in various area.ENSO influences water cycle process significantly.Precipitation is one of the important link of water cycle.The research of water vapor source is a hot point of global change and environment evolution.The variance of the abundance of ¹⁸O and D these two stable isotopes in precipitation has a close relationship with variance of temperature,amount and the location of land and sea et al.of the water vapor source.Therefore,it will trace the vapor source efficiently.Shanghai is in East Asian Monsoon Area and the the composition of oxygen and hydrogen stable isotopes in the precipitation are affected by ENSO evidently.The impact of ENSO on isotopic composition of precipitation in Shanghai inter-annual and inter-decadal will provide the scientific basis to understand the local water cycle,water vapor transport deeply,and to reconstruct ENSO paleven.This study analyzes the characteristics of oxygen and hydrogen isotopes of precipitation in Shanghai and the indication to ENSO in inter-annual scale and inter-decadal scale.Use 70 precipitation samples during August,2014^August 2015to study the impact of specific El Ni?o event to isotopic composition of precipitation in Shanghai inter-annual.Combining the?¹⁸O and?D data in precipitation from Nanjing?S1?,Shanghai?S2?,Wuhan?S3?,Fuzhou?S4?,Hong Kong?S5?thess 5 stations during 1961²012 with that 70 samples mentioned before,with the addition of 206experimental data of Shanghai during January 2012^February 2017,to analyze the relationship between ENSO and isotopic composition of precipitation in Shanghai inter-decadal.The main conclusion as following:1.During a single El Ni?o event,the variance of?¹⁸O and?D of precipitation in Shanghai-83‰^-2‰and-12.0‰^-0.2‰.?¹⁸O in precipitation samples shows low value in summer and autumn,and high value in winter and spring.The Annual Meteoric Water Line in Shanghai is?D=7.07?¹⁸O+3.90?r=0.86,?=0.001,n=70?,the slope and intercept are lower than global and domestic;The slopes and intercepts in spring and summer are smaller than summer and winter.The samples of precipitation with larger amount plays a decisive role on the slope and intercept of MWL in the research region.?¹⁸O of precipitation in Shanghai during El nino doesn't show an obvious temperature effect inter-annual.But a weak temperature effect is showed in winter.Amount effect is showed significantly in autumn and winter,especially in autumn.The decline of?¹⁸O with fluctuation in a single rain sample proves the direct impact of water vapor source on isotopic composition.2.?¹⁸O and d of precipitation in Shanghai have a close connection with ENSO inter-annual.The normal year September 2014,the?¹⁸O in precipitation is-7.0‰.During El Ni?o,?¹⁸O are heavier than September every month except January July and October.Comparing to Normal phase,long-term transport vapor from the Indian Ocean is less,short-term transport vapor from the Pacific Ocean is more,so that?¹⁸O of precipitation are higher before El Ni?o.d value of precipitation are influence by the change of water vapor source.d value are lower before El Ni?o,and higher during El Ni?o.Meanwhile,d value and SOI have weak negative correlation:?¹⁸O=0.07SOI_Nion3.4+0.05?r=-0.40,?=0.01,n=12?.3.Isotopic composition of precipitation in Shanghai are different during different ENSO type inter-decadal.?¹⁸O and?D are positive during El Ni?o than all the other time.However,isotopic composition of precipitation in summer and autumn are low and has a high value in winter and spring through all the time.It shows the general rule of seasonal distribution in Shanghai precipitation.The MWL in Shanghai is close to GMWL.But the environmental factors such as temperature and amount are influenced by ENSO apparently,which induce the slope and intercept are larger in El Ni?o than in all the other time.4.Different phase of ENSO has different impact on various isotopic composition environmental factors.5 stations data show obvious anti-temperature effect,amount effect,water vapor pressure effect through the research time.Lengthen time scale will make effect research more precise.During different ENSO phases,every environmental factor affect in different degree.These environmental effects affect each other,such as temperature effect,amount effect and water vapor pressure effect are significant during La ni?a than the other phase.5.The strength of ENSO affect?¹⁸O and d value of precipitation obviously.?¹⁸O is lower in summer and autumn,and is higher in winter and spring.And?¹⁸O has negative correlation with ONI and SSTA,which are the index of ENSO.Water vapor in summer precipitation mainly comes from the Pacific Ocean by short-term transport during El Ni?o,so that the?¹⁸O is more positive.And the?¹⁸O is more and more negative as the ENSO is stronger and stronger.d value of precipitation also has a negative correlation with ONI and SSTA.The strength of ENSO affect d value by the impact of relative humility in water vapor source.The stronger the El Ni?o is,the smaller the d value is.And the stronger the La ni?a is,the larger the d value is.However,the strength of ENSO doesn't have apparent impact on environmental effects.