Abstract
Monthly and event precipitation samples were collected at Tsukuba, and isotopic compositions of oxygen and hydrogen were analyzed for all samples. The isotopic compositions of event precipitation have no remarkable trend of seasonal isotopic change. In regard to the d-excess, however, the cyclic variations are observed, and the values of d-parameter are relatively low in warm period (from April to September) and relatively high in cool period (from October to March). It is confirmed that the temperature effect of isotopes in precipitation exists at Tsukuba from November to March. The isotopic compositions which were calculated by class of precipitation amount show the existence of amount effect obviously. Result of regression analysis indicates above consequence. In cases of snowfall, precipitation from Baiu front and autumnal rain front, the isotopic compositions of precipitation are relatively lighter than those of other cases.
