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Isotopic variations in precipitation at Bangkok and their climatological significance
Author(s) -
He Yuanqing,
Pang Hongxi,
Theakstone W. H.,
Zhang Zhonglin,
Lu Aigang,
Gu Juan
Publication year - 2006
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.6139
Subject(s) - precipitation , climatology , monsoon , environmental science , stable isotope ratio , latitude , isotope , isotopic signature , east asian monsoon , stalagmite , atmospheric sciences , geology , oceanography , meteorology , geography , holocene , physics , geodesy , quantum mechanics
Abstract The stable isotopic composition of precipitation from low to mid latitudes contains information about changes of some climatic factors, such as temperature, precipitation and atmospheric circulation patterns. However, the isotopic variations in the area are very complicated because of the combined influences of these factors. Proper interpretation of the patterns of isotopic variations for palaeoclimate reconstructions in this area requires a detailed understanding of these complex stable isotope controls. The isotopic data (δ 18 O and δ 2 D) in precipitation at the International Atomic Energy Agency–World Meteorological Organization Bangkok station were collected and analysed because of the relatively long and unbroken isotopic records and the particular geographical location. The isotopic variations at Bangkok have strong seasonal patterns owing to distinct source regions in different seasons. In summer, the remote sources of water there can influence the δ 18 O values significantly, which is verified by the simple Rayleigh model. In winter, the mixing of isotopically distinct air masses with different origins, i.e. the continental and oceanic air masses, accounts for the isotopic variations. In the transition periods of the Asia–Australia monsoon, namely in May and October, the local vapour contribution may play a role in the isotopic ratios. On the interannual time‐scale, the influences of El Niño–southern oscillation (ENSO) and the Indian Ocean dipole (IOD) on isotopic composition are examined. The indications are that both the ENSO and IOD indices have a significant correlation with the δ 18 O ratios, and that the δ 18 O ratio in summer rains is significantly more enriched (depleted) during the warm (cold) phase of ENSO/IOD events. All the results suggest that it is useful for us in understanding the water cycling process and may be helpful in palaeoclimate reconstruction in this monsoon region. Copyright © 2006 John Wiley & Sons, Ltd.