Coupled Effects of Moisture Transport Pathway and Convection on Stable Isotopes in Precipitation across the East Asian Monsoon Region: Implications for Paleoclimate Reconstruction

Abstract

This study investigated the variations in stable oxygen isotopes in daily precipitation (δ18Op) collected between 2010 and 2013 at four sites across the East Asian monsoon region to address the controversy whether local meteorological factors, moisture transport pathway or convection dominates the δ18Op changes. We found that the δ18Op time series exhibit opposite seasonal patterns between the southern and northern sites; however, relatively low δ18Op values occur at each site during summer. The opposite seasonal patterns are closely related to the proportional change in the contributions from oceanic (> 52% in the south) and continental (> 85% in the north) moisture sources. Moisture transport distances also influence the seasonal δ18Op fluctuations. In the south, the moisture transported over short distances from the middle of the western Pacific Ocean results in relatively high δ18Op values during the pre-monsoon season. In contrast, long-distance transport of moisture from the Indian and Equatorial Pacific Oceans during the monsoon season results in relatively low δ18Op values. In the north, relatively low δ18Op values during the monsoon season can be attributed to an increase in relatively distant moisture originated from the middle of the western Pacific Ocean. Convection only plays a role in affecting δ18Op values in the south during the monsoon season. Our study suggests that moisture transport pathway (moisture sources and moisture transport distances) is a major factor that governs seasonal variations in δ18Op across the East Asian monsoon region, which has implications for the interpretation of paleoclimate records from this region.

Dataset of Stable Isotopes of Precipitation in the Eurasian Continent

“…7). The d-excess, which represents the deviation of the deuterium excess from the global average, is lower in summer and higher in winter, indicating seasonal changes in the source and transport distance of water vapor (Zhang et al, 2021). Furthermore, there are regional differences in the seasonal variation of d-excess.…”

“…The complex natural environment determines that no single factor has a dominant control over the stable isotopes in precipitation in that region, and the composition of stable isotopes in precipitation is influenced by both local and distant factors (Dublyansky et al, 2018). In the eastern coastal region of China, the relative enrichment of stable isotopes in precipitation is due to the proximity to the evaporative source of the ocean, leading to an increased abundance of heavy isotopes (Zhang et al, 2021). In the arid region of central Asia, there is a strong correlation between stable isotopes in precipitation and temperature, and the enrichment or depletion of stable isotopes in precipitation reflects the trend of temperature change (Zhu et al, 2023).…”

Controls on Stable Water Isotopes in Monsoonal Precipitation Across the Bay of Bengal: Atmosphere and Surface Analysis

“…We identified the air mass back trajectories using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model version 4.0 (Stein et al, 2015). Detailed descriptions on the moisture source diagnostic method can be found in Text S4 in Supporting Information S1 (Cai et al, 2018;Zhang et al, 2021). To investigate the influences of upstream accumulative convection on δD p , we traced changes in precipitation amount and outgoing longwave radiation (OLR) (Text S3 in Supporting Information S1) along the back trajectories using the HYSPLIT model.…”

Altitude Correction of GCM-Simulated Precipitation Isotopes in a Valley Topography of the Chinese Loess Plateau

“…The precipitation isotopes at a 6 h interval (0:00, 6:00, 12:00, and 18:00 UTC) as well as corresponding surface air pressure from 1979 to 2020 were simulated using isoGSM2 [34]. This stable isotope-enabled general circulation model simulates high-resolution variations in stable isotopes in precipitation and water vapor, which has been applied to examine atmospheric water transport [35][36][37].…”