Scientists Reveal How Much Rain Disappears Before Reaching the Ground on the Qinghai–Tibet Plateau
- MM24 News Desk
- Oct 15
- 2 min read
Credit:(Xinhua)
Chinese researchers have closed a long-standing research gap by providing the first long-term observational analysis of below-cloud evaporation in the hinterland of the Qinghai–Tibet Plateau, one of the most vital regions for Asia’s water resources. The breakthrough was announced by the Northwest Institute of Eco-Environment and Resources (NIEER) under the Chinese Academy of Sciences (CAS).
According to the NIEER, the findings mark a significant advance in the quantitative study of below-cloud evaporation, offering new insights into how the high-altitude hydrological cycle responds to global warming. The research was jointly conducted by scientists from the NIEER and the Institute of Mountain Hazards and Environment of the CAS.
The “Water Tower of Asia” Under Study
Often called “Asia’s water tower,” the Qinghai–Tibet Plateau acts as a critical reservoir feeding major rivers across the continent. The plateau’s stable precipitation isotopes play a key role in understanding both regional and global water cycles and are widely used in paleoclimate reconstruction and hydrological research, explained He Xiaobo, associate researcher at the NIEER.
Within this vast region, the Tanggula Range—a climate transition zone and the plateau’s hydrological core—is witnessing notable warming and increased wetness. Until now, however, quantitative data on below-cloud evaporation in this area were scarce due to its extreme environment and the difficulties of maintaining long-term observation stations.
A 12-Year Record of High-Altitude Hydrology
Using 12 years of continuous observational data, the research team simulated the process of below-cloud evaporation by integrating stable isotope measurements of precipitation with meteorological data and applying the Stewart model. This allowed them to estimate sub-cloud evaporation rates and assess how these processes alter precipitation isotopes in the Tanggula Range.
The analysis quantified the extent to which below-cloud evaporation affects isotope composition, revealing the key driving factors and their mechanisms. The team found that the annual weighted mean of the remaining raindrop fraction was 88.1 percent, showing a gradual weakening of below-cloud evaporation intensity over the study period.
Significant isotope changes were observed as raindrops descended from cloud base to ground level, indicating that below-cloud evaporation led to enrichment of heavier isotopes in precipitation across the central plateau.
A Foundation for Future Climate Research
By clarifying the role of below-cloud evaporation in shaping both precipitation and isotope composition, the study provides an important scientific basis for paleoclimate reconstruction and water resource management across the Qinghai–Tibet Plateau.
He Xiaobo noted that the team plans to expand its observation network and extend its research over longer timescales to further explore how the plateau’s water cycle responds to global climate change.
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