Different Dynamics Drive Indian Ocean Moisture to the Southern Slope of Central Himalayas: An Isotopic Approach

• Published in: Geophysical Research Letters
• Main Authors: Rong Guo, Wusheng Yu, Jingyi Zhang, Stephen Lewis, Lazhu, Yaoming Ma, Baiqing Xu, Guangjian Wu, Zhaowei Jing, Pengjie Ren, Zhuanxia Zhang, Qiaoyi Wang, Dongmei Qu
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: precipitation oxygen isotopes; the westerlies; anomalous circulations; Indian summer monsoon; convection; the central Himalayas; Geophysics. Cosmic physics; QC801-809; Indian; ice core
• Online Access: https://doi.org/10.1029/2024GL109359; https://doaj.org/article/83fcad86f19d4b96a2673905a0e119b1

Abstract This study uses precipitation oxygen isotopes (δ18Op) to examine key dynamics that deliver moisture to the southern slope of central Himalayas over different seasons. Results show that the majority of pre‐monsoon δ18Op values are relatively high and controlled by the westerlies and local moisture. However, some abnormally low δ18Op values coincide with higher precipitation amounts during the pre‐monsoon season due to moisture driven northwards from the Bay of Bengal and Arabian Sea to central Himalayas by anomalous circulations (quasi‐anticyclone, anticyclone, or/and westerlies trough). The size and location of the quasi‐anticyclone also influences the magnitude of the δ18Op decrease. In comparison, the monsoon δ18Op values are lower due to the combined effects of the Indian summer monsoon and convection. Our findings indicate that researchers need to consider the signals of abnormally low δ18Op values during the pre‐monsoon season when attempting to interpret ice core and tree‐ring records from central Himalayas.