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Dust is the predominant type of aerosol over the Tibetan Plateau (TP) due to the existence of surrounding significant dust sources. However, the contributions of different dust sources to the distribution and variation of dust over the TP and corresponding mechanisms are still being explored. By separating emissions from different dust sources in a numerical model, this study detected that dust originating from East Asia, the Middle East, and North Africa are the main contributors to spring dust over the TP, accounting for 42%–68%, 13%–27%, and 9%–25% of the total dust concentration, respectively. East Asian dust primarily affects the dust over the central and northern parts of the TP, whereas Middle Eastern and North African dust mainly contributes to the dust over the western and southern parts of the TP. Additionally, the variation in dust over the TP is related to East Asian and North African dust, which contribute 58% and 35% of the total variation, respectively. The mechanism underlying this association is attributable to the SST over the northern North Atlantic and updrafts over the northern slope of the TP: the increased SST enhances westerlies from North Africa to East Asia and northwesterly winds over the northern slope of the TP and combines with the stronger westerlies to promote the transport of East Asian and North African dust to the TP. Consequently, it is necessary to focus on the impact of multiple dust sources on the dust over the TP. [ABSTRACT FROM AUTHOR]

The Qiangtang Basin, located in the Tibetan Plateau, is an appropriate area to verify the Lhasa–Qiangtang collision, which was recorded by the middle-upper part of the Yanshiping Group (the Xiali and Suowa Fms) in the basin. However, the chronology of the Xiali and Suowa Fms is HYPERLINK "javascript:;" controversial, which limits comprehending the timing of the Lhasa–Qiangtang collision. More importantly, HYPERLINK "javascript:;" oil HYPERLINK "javascript:;" shale and salt springs were exposed in the Xiali and Suowa Fms in the basin. 544 paleomagnetic samples were collected from the Yanshiping section in the basin in order to reveal the timing of the Lhasa–Qiangtang collision from the view of paleomagnetic ages of the two formations. However, we did not give credible magnetostratigraphic ages of the two formations because of ammonite fossils, a global primary standard for the Jurassic strata correlation, without being found in the last study. Yin (2016) revised the long-term HYPERLINK "javascript:;" controversial paleontological age of the Suowa Fm. from a Tithonian age of the Late Jurassic or a Berriasian age of the Early Cretaceous, to a Middle Bathonian–Middle Callovian age of the Middle Jurassic based on new ammonite fossils. Considering ammonite fossils as a powerful tool and a global primary standard for the Jurassic strata correlation, we attempted to correlate the last magnetostratigraphy with the GPTS 2012 again. Magnetostratigraphic ages of 164.0–160.2 Ma and 160.2–156.8 Ma for the Xiali and Suowa Fms are suggested, respectively. The timing of the Lhasa–Qiangtang collision (156.8–154.9 Ma) is revealed from the magnetostratigraphic ages and the zircon U–Pb age of the Xueshan Fm, 154.9 (+6.8/−1.6) Ma, overlying the Suowa Fm in the Yanshiping section. [ABSTRACT FROM AUTHOR]

Atmospheric simulation-based gridded precipitation datasets have been widely used in hydrological and land surface modeling, but may contain larger uncertainties in mountainous regions. This study compared the performance of the fifth European Centre for Medium-Range Weather Forecasts reanalysis (ERA5) precipitation data with two fused precipitation datasets [China Meteorological Administration Land Data Assimilation System version 2.0 (CLDAS2.0) and China Meteorological Forcing Dataset (CMFD)] in the Yarlung Zangbo River basin (YZRB), which has a complex terrain and climate. Compared to in situ observations, ERA5 could capture the spatial--temporal pattern of precipitation but showed high precipitation, especially in the downstream region (lower Nuxia discharge station). In terms of the correlation coefficient, the overall performance of the ERA5 data was slightly worse than that for CMFD data at both the monthly and yearly scales, and was comparable to that of the CLDAS2.0 data. Given that the spatial mismatch between the gridded and in situ data may influence the evaluation, we also employed the water balance method to constrain basinwide precipitation amounts. We found that CLDAS2.0 and CMFD precipitation data tended to cause long-term water imbalance, and ERA5, with a much larger multiyear average annual precipitation, could better close the water budget. Further analysis showed that the differences in multiyear average annual precipitation between ERA5 and in situ observations were closely related to the slope and standard deviation of the subgrid-scale orography, indicating the substantial influence of subgrid topography on precipitation simulation. These findings highlight that ERA5 could be a potential reference dataset for hydrological modeling of the YZRB. [ABSTRACT FROM AUTHOR]

The unique characteristics of land–air coupling and troposphere–stratosphere interaction over the Tibetan Plateau (TP), the highest landform in the world, play a vital role in weather and climate on regional and global scales. Although a great deal of research has been carried out, large gaps remain in our understanding of TP land–air coupling and its climate effects, due to a lack of observations and the issue of model biases. To address these obstacles, a 10-yr national research program entitled "Changes in the Land–Air Coupled System over the Tibetan Plateau and its Impacts on Global Climate (LASTPIC)" was launched by the National Natural Science Foundation of China in January 2014. What LASTPIC does revolves around three aspects: TP land–air coupled processes; TP's influence on global climate; and reanalysis and model. This paper mainly focuses on the data collection, scientific understanding, and model development of LASTPIC in terms of TP land–atmosphere–ocean coupling and its global climate impacts since program's inception. [ABSTRACT FROM AUTHOR]

In this study, the spatiotemporal changes and driving factors of evapotranspiration (ET) over the Tibetan Plateau (TP) are assessed from 1961 to 2014, based on a revised generalized nonlinear complementary (nonlinear-CR) model. The average annual ET on the TP was 328 mm. The highest ET value (711 mm) was found in the forest region in the southeastern part of the TP, and the lowest value (151 mm) was found in the desert region in the northwestern part of the TP. In terms of the contribution of different subregions to the total amount of ET for the whole plateau, the meadow and steppe regions contributed the most to the total amount of ET of TP, accounting for 30% and 18.5%, respectively. The interannual ET presented a significant increasing trend with a value of 0.26 mm yr−1 from 1961 to 2014, and a significant positive ET trend was found over 35% of the region, mainly in the southeastern part of the plateau. The increasing trend of ET in swamp areas was the largest, while that in the desert areas was the smallest. In terms of the seasonality, the ET over the plateau and different land-cover regions increased the most in summer, followed by spring, while the change in ET in winter was not obvious. The energy factors dominated the long-term change in the annual ET over the plateau. In addition, the available energy is the controlling factor for ET changes in humid areas such as forests and shrublands. Energy and water factors together dominate the ET changes in arid areas. [ABSTRACT FROM AUTHOR]

Dramatic warming in the late Oligocene occurred after 8 Ma, characterized by ocean warming and a collapse of the Antarctic ice sheet (the late Oligocene warming event [LOWE]); however, few terrestrial records have yet been employed to verify the LOWE and investigate its associated driving forces. The Nima Basin, located in the central Tibetan Plateau contains thick Oligocene sediments, allowing its ecological record to be used as verification of the LOWE. Here we used the reconstructed vegetation record from the Nima Basin in the 1,100‐m‐thick DZC section, aided with zircon U‐Pb dating of the interbedded tuffite layers. Two tuffite layers yielded ages of about 23.4 and 24.8 Ma; thus, the sedimentary age of the whole section is predicted to be 27.5–22.4 Ma. Sporopollen analysis revealed that the dominant taxa throughout the whole section were conifers (over 85%), including Piceapollis, Pinuspollenites, and Abietpollenites. One notable feature is that the broad‐leaved trees (e.g., Quercoidites and Meliaceoidites) increased obviously (averaging from 0.9% to 6.6%, max 41.2%) after 25.6 Ma. This change could be interpreted as a response to late Oligocene global warming, which changed the forest line and corresponding plant species composition. The mean average precipitation of 400–850 and 800–1,000 mm, respectively, inferred from the above vegetation types in the Nima Basin, both exceed the present 150 mm. This indicates that the south Asian monsoon had already developed in the Oligocene and that the LOW event accompanied the global warming. Key Points: The U‐Pb dating shows the DZC section; Nima Basin was deposited mainly in the late OligoceneThe sporopollen results of the DZC section show conifers were dominant but angiosperms increased after 25.58 MaThe changed vegetation was a response to the LOWE and suggested the south Asian monsoon enhanced at that time [ABSTRACT FROM AUTHOR]

Accurate parameters that describe land-air exchange processes are essential for studying and predicting atmospheric processes over the Tibetan Plateau. Radiation, atmospheric thermal and moisture conditions, and turbulent heat and momentum fluxes were measured in the Yarlung Zangbo River, southeast Tibet, in May-July 2013. Based on the data, land-air exchange parameters were derived over the grassland surface, including the aerodynamic roughness length z0m, thermal roughness length z0h, the excess resistance to heat transfer kB−1 (where k represents the von Kármán constant and B−1 represents the Stanton number), and momentum and heat transfer coefficients ( C D and C H, respectively). The average z0m was 7.0 cm, with a standard deviation of 1.4 cm; these values are higher than those observed in the central and western plateau regions and may have been affected by the tall grass and bush surface covers that surrounded the observation site. The average kB−1 was 5.7 ± 1.8, which is higher than that in other plateau regions in the same season. The average C D during the observation period, (11.9 ± 1.6) × 10−3, is also higher than that of other plateau regions. The commonly used iterative scheme and three noniterative turbulent flux parameterization schemes were evaluated over southeast Tibet using the above observational data. Parameter C D was underestimated by most schemes, whereas C H was overestimated by all schemes. Additional studies suggested that the iterative scheme performed best in retrieving the land-air exchange parameters and can be applied over southeast Tibet. [ABSTRACT FROM AUTHOR]