Hydrogen and oxygen isotopes in precipitation in the northern part of the North China Plain: climatology and inter-storm variability

To clarify the processes of atmospheric water vapour transport to the northern part of the North China Plain (NCP), isotopic variations in precipitation are investigated. Pattern of seasonal variation in the isotopic composition of precipitation over China can be classified into three types: winter depression, summer depression and intermediate. The northern NCP is located at the northern margin of the region where isotopic composition decreases in summertime, associated closely with the Asian summer monsoon. Inter-storm variability of isotopic composition over the northern NCP during the monsoon season has an inverse relationship with atmospheric moisture content, although it cannot be accounted for by the amount effect. Thus, the isotopic composition is inferred to be primarily controlled by large-scale monsoon activity, which supplies water vapour into the northern NCP, rather than by local precipitation processes. From an analysis based on a relationship between the deuterium excess and humidity conditions at possible oceanic source areas, it is revealed that precipitating water in the early monsoon season originates in the South China Sea, and its source area tends to shift to the East China Sea and/or Yellow Sea in the later period of the season. Copyright (C) 2004 John Wiley Sons, Ltd.