The relationship between δ18O characteristics of the precipitation (heavy rainfall or rainstorm) and its water vapor sources in Guilin, China
ZHU Xiaoyan
ZHANG Meiliang
WU Xia
PAN Moucheng
Abstract：It is significant to use stable isotopic of modern meteoric precipitation for the global or regional water cycle research,which is also important component in reconstructing paleoclimate in the studies of ice cores,lake sediments,stalagmites and the others.Oxygen and hydrogen stable isotopes (δ18O and δD) in the meteoric precipitation collected from each heavy rain event from January to December in 2012 in Guilin,are studied in this paper.The overall correlation between δ18O and δD is obtained as δD-8.8 δ18O +17.96 from 132 stable hydrogen and oxygen isotope components.During the monitoring period,δ18O values of the meteoric precipitation varied-13.56 ‰ to +1.07 ‰ with an average δ18O value of-5.78 ‰ (VSMOW) and the δD values of the meteoric precipitation are between-101.52 ‰ and +16.02 ‰ with an average of 41.03‰ (VSMOW).Using Backward Trajectory technology of the HYSPLIT model and the data of precipitation isotopes in Guilin,it was found that the water vapor sources of the meteoric precipitation in the summer time (May to October) is mainly controlled by the water vapor of the marine airmasses from the Indian Ocean or Gulf of Bengal and the South China Sea,secondly from the West Pacific Ocean.The δ18O value of the meteoric precipitation is more negative with average δ18O value of-8.02 ‰ (average of 64 groups) and accounts for 53.3％ of the total meteoric precipitation.And the water vapor sources of the meteoric precipitation in the winter monsoon (November to the next April) are mainly affected by the warm-moist airmass es of the West Pacific Ocean and the continental cold air mass flow carried by the westerly wind zone (or the winter monsoon) and sometimes superposed by the part of the local evaporation moisture circulation.In this period,the δ18O value of the meteoric precipitation is more positive with average of 2.86 ‰ (average of 68 groups) and accounts for 46.7％ of the total meteoric precipitation.The research results show that the stable isotopic composition of modern meteoric precipitation in Guilin is related to the monsoon type and source of the meteoric precipitation cloud and property of the meteoric precipitation.The δ18O value of the meteoric precipitation from far transmission of water vapor of the marine air masses carried by the summer monsoon is more negative.In contrast,the δ18O value is more positive while the meteoric precipitation is controlled by the continental cold air mass flow carried by the westerly wind zone,or by the overlay of winter monsoon with localised air moisture circulation.These results indicate that the different sources of water vapor have significant influences on the δ18O variation of the meteoric precipitation.Therefore,analysis of δ18O in the meteoric precipitation,especially its seasonal variation characteristics in turn reveals the water moisture sources of local meteoric precipitation.
Keywords：precipitationoxygen isotope characteristicsBackward Trajectory technologywater vapor sourcesGuilin
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：23( 139-161 )