Variability of Isotope Composition of Precipitation in the Southeastern Tibetan Plateau from the Synoptic to Seasonal Time Scale

Abstract

Daily precipitation samples were collected at four sites in Mount Yulong and Mount Meili regions of southeastern Tibetan Plateau and analyzed for isotopic composition. Combined with water vapor isotopic composition derived from satellites data (Infrared Atmospheric Sounding Interferometer, Tropospheric Emission Spectrometer, and Greenhouse gases Observing Satellite), the factors controlling the variability in the isotopic composition of precipitation are investigated at the synoptic, intraseasonal, and seasonal time scales. At the seasonal scale, the isotope composition in precipitation is controlled by processes along air mass trajectories affecting the water vapor at the large scale (>200 km), especially upstream deep convection and air mass origin, and by local processes transforming the large‐scale water vapor isotopic composition into the precipitation composition, especially rain evaporation and local circulation. At the intraseasonal and synoptic scales, the isotope composition in precipitation is mainly controlled by these local processes. The shorter the time scale of isotopic variations, the smaller the spatial imprint of these variations. The fact that different factors control the isotopic variability at different time scales calls for caution when applying relationships observed at these time scales to interpret isotopic variations at paleoclimatic time scales. While general circulation models successfully capture the isotopic variability and its controlling factors at the seasonal scale, it fails to simulate them at shorter time scales, because it fails to simulate the local processes.

Isotopic Evolution in Snowpacks from a Typical Temperate Glacier in the South-Asia Monsoon Region

“…Taking S6 as an example, the lower section of the snowpack in which snow accumulated in the autumn was depleted in heavy isotopes, whereas the upper-section snow, which mainly accumulated in March and April, was enriched in heavy isotopes. This indicates that autumn precipitation was depleted in 18 O while spring precipitation was enriched in 18 O in the study area, which is consistent with the precipitation of the South Tibetan Plateau [28].…”

“…Environmentally stable isotopes have been used extensively as indicators of climatic and environmental changes in meteorological, hydrological, glaciological and environmental fields in the past decade [14][15][16][17][18][19][20][21][22][23]. It has been reported in cold regions that stable isotopes in precipitation, snow and ice cores are closely related to meteorological factors and climate change [24][25][26][27][28]. Specifically, stable isotopes in snowpack records reflect the condition of atmospheric deposition and post-depositional processes and provide important information for ice core dating using isotopes [29][30][31][32].…”

What Controls the Water Vapor Isotopic Composition Near the Surface of Tropical Oceans? Results From an Analytical Model Constrained by Large‐Eddy Simulations

“…It is also ultimately the only source of water vapor in the tropical free troposphere, since water vapor in the free troposphere ultimately originates from convective detrainment (Sherwood, 1996), and convection ultimately feeds from the air close to the surface (Bony et al., 2008). In addition, the precipitation isotopic composition often varies in concert with the water vapor (Aemisegger et al., 2012; Graf et al., 2019; Nlend et al., 2020; Shi et al., 2020; Tremoy et al., 2012). Therefore, the water vapor isotopic composition near the surface of tropical oceans serves as an initial condition for the isotopic composition in land waters and in the tropospheric water vapor everywhere on Earth.…”

Seasonality of moisture supplies to precipitation over the Third Pole: a stable water isotopic perspective

“…So far, water stable isotopes in precipitation have demonstrated wide applications to earth sciences on the TP, having been used to detect moisture source and intensity of related atmospheric circulations [12][13][14][15][16] , reflect the influences of local and/or large-scale atmospheric circulation processes on precipitation that pertains closely to the water cycle [17][18][19][20][21] , transcend time to link modern variation features with climate significances in paleoproxies 5,12,[22][23][24][25][26] and inform of the plateau uplift history with their imprints on rock records 27,28 . Various studies on water stable isotope compositions have been conducted in the southern, southeastern, northeastern and northwestern parts of TP [29][30][31][32] , revealing the dependency of δ 18 O in precipitation on moisture sources 17,33 , relative humidity 22 , cloudiness 34 , and integrated convective activity along upstream air mass trajectories 17,30,[35][36][37] . Those studies highlighted the spatial heterogeneity of precipitation and its water stable isotopic compositions across the TP, which pertains to atmospheric circulations.…”

“…Those studies highlighted the spatial heterogeneity of precipitation and its water stable isotopic compositions across the TP, which pertains to atmospheric circulations. An overall picture of moisture sources and associated storm activity along air mass trajectories would be conducive to a better understanding of controlling factors over isotopic variations at the seasonal scale 37 , and thus finally contributes to a better understanding of the westerlies-monsoon interactions under current climate scenarios.…”