Long‐distance atmospheric moisture dominates water budget in permafrost regions of the Central Qinghai‐Tibet plateau

Abstract

Precipitation plays an important role in permafrost hydrology; it can alter the hydrothermal condition of the active layer and even influence the permafrost aggradation or degradation. Moisture recycling from evaporation and transpiration can greatly contribute to local precipitation in some regions. This study selected four monitoring sites and used an isotope mixing model to investigate local moisture recycling in permafrost regions of the central Qinghai-Tibet Plateau (QTP). The results showed that the local water vapour flux in the summer and autumn were dominantly influenced by westerlies and the Indian monsoon. Moistures for precipitation in Wudaoliang (WDL) and Fenghuoshan (FHS) mainly came from the western QTP, eastern Tianshan Mountains, western Qilian Mountains, and the surrounding regions. In comparsion, more than half of precipitation at Tanggula (TGL) was mostly sourced from the Indian monsoon. Local moisture recycling ratios at the four sites ranged from 14% ± 3.8% to 31.6% ± 4.8%, and depended on the soil moisture and relative humidity. In particular, the higher soil moisture and relative humidity promoted local moisture recycling, but frozen ground might be a potential influencing factor as well. The moisture recycling ratios of the study area were consistent with the results from both the Qinghai Lake Basin and the Nam Co Basin, but differed from those of the northwestern QTP. This difference may indirectly confirm the great spatial variability in precipitation on the QTP. Moreover, the rising air temperature and ground temperature, increasing precipitation, higher soil moisture, higher vegetation cover, and expanding lakes in the study area may be conductive to enhancing future local moisture recycling by altering ground surface conditions and facilitating the land surface evaporation and plant transpiration.

Global diagnosis of land–atmosphere coupling based on water isotopes

“…First, the mean turnover time (calculated by dividing the number of materials present in a system by the into or out flux rate for the materials) of water vapour in the global atmosphere is around 10 days concerning the net evaporation or precipitation fluxes. Second, the sources of water vapour are various, including oceanic evaporation vapour, terrestrial evapotranspiration vapour along the moisture trajectory, and locally recycled vapour 25 , 26 . Both the oceanic and the terrestrial vapour belong to the external water cycle.…”

The Variability of Summer Atmospheric Water Cycle over the Tibetan Plateau and Its Response to the Indo-Pacific Warm Pool

“…Many have focused on the PRR over the TP, as shown in Table 1. The PRR of the TP in summer during the past forty years is approximately 23-28% [28,29], while the contribution rate of the southern TP to precipitation is 30% [30], and the central and western TP is nearly 14-18% [31,32]. Meanwhile, the PRR in the northern TP increased with the increase in precipitation, and the southern TP decreased with the decrease in precipitation [18].…”

“…For different areas of the TP and western China, the PRR is 9% in the Tianshan Mountains; 16% in the Urumqi Oasis as an arid region [33,34]; and 20-24% on the northern slope of the Qilian Mountains, which increases with elevation [35,36], by 20% and 19% for the Yangtze and Yellow River basins [37], and is about 14% in the Tarim River Basin [38]. Station Data [25,41] Central TP 14-32% Isotopic mixing model July to September, 1996September, -1997 Station Data [32] Endorheic TP 17-22% WAM-2 1979-2015 ERA-Interim, MERRA-2, and JRA-55 [25] Quantitative studies based on reanalysis datasets, stable isotopes of precipitation, and circulation simulations show the summer water vapor on the TP mainly comes from the long-distance transport channel from the equatorial western Indian Ocean to the Arabian Sea and the Bay of Bengal, and a small part comes from the westerly wind from Eurasia as shown in Figure 1a [42][43][44][45][46]. The interannual and interdecadal changes in the water vapor budget (WVB) over the TP are not only directly affected by largescale circulations.…”

Mechanism of the summer rainfall variation in Transitional Climate Zone in East Asia from the perspective of moisture supply during 1979–2010 based on the Lagrangian method

“…Characterized by semi-arid climate, limited water supply makes it necessary to explore moisture source of TCZ. Eulerian method is a common method to analyze water vapor transportation and the budget of water vapor in an atmospheric column with grid data (Trenberth and Guillemot 1995, Simmonds, Bi et al 1999, Oshima, Tachibana et al 2015, Zhu, Wu et al 2020). However, it provides simple moisture transport paths and fails to show detailed information on the geographical sources of the moisture since the meteorological eld is transient (Sodemann, Schwierz et al 2008, Drumond, Nieto et al 2011).…”