| 1. |
- Ehlers, Todd A., et al.
(author)
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Past, present, and future geo-biosphere interactions on the Tibetan Plateau and implications for permafrost
- 2022
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In: Earth-Science Reviews. - : Elsevier BV. - 0012-8252. ; 234
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Journal article (peer-reviewed)abstract
- Interactions between the atmosphere, biosphere, cryosphere, hydrosphere, and geosphere are most active in the critical zone, a region extending from the tops of trees to the top of unweathered bedrock. Changes in one or more of these spheres can result in a cascade of changes throughout the system in ways that are often poorly understood. Here we investigate how past and present climate change have impacted permafrost, hydrology, and ecosystems on the Tibetan Plateau. We do this by compiling existing climate, hydrologic, cryosphere, biosphere, and geologic studies documenting change over decadal to glacial-interglacial timescales and longer. Our emphasis is on showing present-day trends in environmental change and how plateau ecosystems have largely flourished under warmer and wetter periods in the geologic past. We identify two future pathways that could lead to either a favorable greening or unfavorable degradation and desiccation of plateau ecosystems. Both paths are plausible given the available evidence. We contend that the key to which pathway future generations experience lies in what, if any, human intervention measures are implemented. We conclude with suggested management strategies that can be implemented to facilitate a future greening of the Tibetan Plateau.
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| 2. |
- Sun, He, et al.
(author)
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Contrasting precipitation gradient characteristics between westerlies and monsoon dominated upstream river basins in the Third Pole
- 2020
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In: Kexue Tongbao/Chinese Science Bulletin. - 0023-074X .- 2095-9419. ; 65, s. 91-104
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Journal article (peer-reviewed)abstract
- © 2020, Science Press. All right reserved. Based on precipitation observations from 256 gauges in the westerly and monsoon dominated upstream river basins of the Third Pole (TP), this study determined the relationships between precipitation and elevation. The basins include the upper basins of the Yangtze, Yellow, Lancang, Nujiang, Yarlung Zangbo, Yarkant, Indus, Amu Darya, and Syr Darya. Using the ERA5 data, this work examined the possible reasons for the difference in the characteristics of precipitation gradient, i.e. analyzing the relationships between the total column water vapor (TCWV), convective available potential energy (CAPE), lifting condensation level (LCL) and elevation, respectively. The feasibility of orographic corrections of precipitation data or observation is validated with the improved VIC land surface hydrological model in two mountain basins in the TP. Mean annual precipitation from gauges generally show decreasing trends (17-128 mm/100 m) with increased elevation (2500-5500 m a.s.l.) in the monsoon dominated basins, i.e. upper Yangtze, Yellow, Lancang, Nujiang, and Yarlung Zangbo, while the orographic enhancements are observed at relatively smaller scales, such as, in the very source regions of the upper Lancang and Nujiang, and Rikaze sub-basin with areas of 11000-67740 km2. On the other hand, in the westerly dominated basins, mean annual precipitation tends to increase with elevation (5-64 mm/100 m) in the upper Yarkant, Indus, Amu Darya, and Syr Darya. The precipitation estimates from ERA5 show a good correspondence with the gauge data (R=0.6-0.9, P<0.05), and exhibit a general consistent precipitation gradient pattern with the gauge observations. The ERA5 variables of TCWV, CAPE, and LCL are useful to understand the factors for the spatial pattern of precipitation vertical gradients in the TP basins with different climate control. The TCWV, CAPE, and LCL represent the vertically integrated moisture, instability and condensation necessary for the generation and development of precipitation. The larger TCWV, higher CAPE and lower LCL enhance precipitation. The decrease of precipitation with elevation in monsoon basins is caused by the decrease of TCWV with elevation, while the increase of precipitation with elevation in westerly dominated basins is a result of increasing CAPE and decreasing LCL with elevation. Hydrological modeling results in the upper Yarkant basin and Rikaze basin indicate that the orographic correction of precipitation data significantly improves the model accuracy, reducing the biases to less than 5% relative to flow observations. This work demonstrates that precipitation correction through vertical gradients is an effective way to derive high mountainous precipitation estimates for hydrological modeling from lowland gauges in the TP, especially in the westerly dominated basins, and in monsoon basins at regional or local scales. Knowledge of the spatial and temporal characters and variations of precipitation over the TP is greatly incomplete, which largely hampers the understanding on climate variability and water availability projections in the TP. This study offers a useful reference to derive reliable mountain precipitation through orographic correction, and also provides a scientific basis to establish precipitation observation network in the Second Tibetan Plateau Scientific Expedition and Research.
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| 3. |
- Xu, Jie, et al.
(author)
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Totaling river discharge of the third pole from satellite imagery
- 2024
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In: REMOTE SENSING OF ENVIRONMENT. - 0034-4257 .- 1879-0704. ; 308
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Journal article (peer-reviewed)abstract
- The high-mountain Third Pole (TP) in Asia is undergoing rapid warming, profoundly impacting river discharge. Changes in precipitation and the degradation of glaciers and permafrost exert a substantial impact on TP rivers, affecting millions downstream. Nevertheless, conventional estimation methods that rely on in -situ observations and models face considerable challenges due to inconsistent data quality and availability, complex terrain, and difficulty in representing hydrological processes. Here, we harnessed the power of high-resolution (3 m) Dove/ PlanetScope satellite images to meticulously measure river width and propose a novel formula for estimating discharge. This approach facilitates a coherent assessment of discharge at various river section shapes. Its efficacy is demonstrated through applying to thirteen high-mountain TP rivers, revealing an estimated total mountain discharge of 3786 billion m 3 during 2017 - 2021, equaling water from approximately 167 Great Lakes. These findings have immediate implications for integrated water resources management at the poorly-gauged transboundary basins of Asia.
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| 4. |
- Yao, Tandong, et al.
(author)
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Recent Third Pole’s rapid warming accompanies cryospheric melt and water cycle intensification and interactions between monsoon and environment: multi-disciplinary approach with observation, modeling and analysis
- 2019
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In: Bulletin of The American Meteorological Society. - 0003-0007 .- 1520-0477. ; :March, s. 423-444
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Journal article (peer-reviewed)abstract
- The Third Pole (TP) is experiencing rapid warming and is currently in its warmest period in the past 2,000 years. This paper reviews the latest development in multidisciplinary TP research associated with this warming. The rapid warming facilitates intense and broad glacier melt over most of the TP, although some glaciers in the northwest are advancing. By heating the atmosphere and reducing snow/ice albedo, aerosols also contribute to the glaciers melting. Glacier melt is accompanied by lake expansion and intensification of the water cycle over the TP. Precipitation has increased over the eastern and northwestern TP. Meanwhile, the TP is greening and most regions are experiencing advancing phenological trends, although over the southwest there is a spring phenological delay mainly in response to the recent decline in spring precipitation. Atmospheric and terrestrial thermal and dynamical processes over the TP affect the Asian monsoon at different scales. Recent evidence indicates substantial roles that mesoscale convective systems play in the TP’s precipitation as well as an association between soil moisture anomalies in the TP and the Indian monsoon. Moreover, an increase in geohazard events has been associated with recent environmental changes, some of which have had catastrophic consequences caused by glacial lake outbursts and landslides. Active debris flows are growing in both frequency of occurrences and spatial scale. Meanwhile, new types of disasters, such as the twin ice avalanches in Ali in 2016, are now appearing in the region. Adaptation and mitigation measures should be taken to help societies’ preparation for future environmental challenges. Some key issues for future TP studies are also discussed.
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| 5. |
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| 6. |
- Zhang, Guoqing, et al.
(author)
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Extensive and drastically different alpine lake changes on Asia's high plateaus during the past four decades
- 2017
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In: Geophysical Research Letters. - 0094-8276. ; 44:1, s. 252-260
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Journal article (peer-reviewed)abstract
- Asia's high plateaus are sensitive to climate change and have been experiencing rapid warming over the past few decades. We found 99 new lakes and extensive lake expansion on the Tibetan Plateau during the last four decades, 1970–2013, due to increased precipitation and cryospheric contributions to its water balance. This contrasts with disappearing lakes and drastic shrinkage of lake areas on the adjacent Mongolian Plateau: 208 lakes disappeared and 75% of the remaining lakes have shrunk. We detected a statistically significant coincidental timing of lake area changes in both plateaus, associated with the climate regime shift that occurred during 1997/1998. This distinct change in 1997/1998 is thought to be driven by large-scale atmospheric circulation changes in response to climate warming. Our findings reveal that these two adjacent plateaus have been changing in opposite directions in response to climate change. These findings shed light on the complex role of the regional climate and water cycles, and provide useful information for ecological and water resource planning in these fragile landscapes.
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