Tibetan Plateau Area Research Articles

Arctic air mass triggered the extreme temperature events recorded in the Laohugou ice core from the northeastern Tibetan Plateau

The frequency and the intensity of extreme temperature events have both increased globally because of the effects of climate warming. Such extreme events should be distinct in high-elevation areas owing to the phenomenon of elevation-dependent warming; however, corroborating evidence remains limited because of scarce observations. This study used the percentile method to identify annual extreme temperature events recorded in the δ18O of the Laohugou ice core (1960–2006) retrieved from the high-elevation area of the northeastern Tibetan Plateau (NETP). Comparison of these events with synchronous observations obtained at surrounding meteorological stations indicated that extreme temperature events identified from the ice core corresponded well with most temperature observations from the meteorological stations, suggesting that the δ18O record could be considered a reasonable proxy for regional temperature. However, occasional discord between the ice core and station records might reflect specific climatic shifts. Using circulation synthesis, the influencing circulation mechanism of each event was determined on the basis of differences in atmospheric parameters between each event and the average climatic state during 1970–2000. A double blocking high with warming over the Ural Mountains and east of Kuril–Kamchatka resulted in Eurasian warming, which transported warm air to the NETP and triggered the extreme high-temperature events. Conversely, a polar vortex in the Arctic led to a cold low over Eurasia, which transported cold air to the NETP causing extreme low-temperature events. The finding that variation of the Arctic air mass triggers extreme temperature events at high elevations in the NETP provides crucial insight for improved comprehension and forecasting of regional extreme temperature events.

Climatic Changes During the Last Two Millennia on the Southern Tibetan Plateau Based on Lake Sediment and Its Forcing Mechanisms

Based on the high resolution precipitation/moisture series over the Southern Tibetan Plateau in the past two millennia, the spatiotemporal pattern of drought-wet change over the Southern Tibetan Plateau are discussed by regional comparison and integrated analysis. The characteristics and mechanisms of climate change during the two typical periods, i.e. the Medieval Climate Anomaly (MCA, AD 600-1400) and the Little Ice Age (LIA, AD 1400-1900), are discussed emphatically. The results show that climate over the Southern Tibetan Plateau has changed significantly in the past two thousand years. It changed from wet to dry in AD 1-600, keeping dry in AD 600-1400, and then wet after AD 1400. The LIA and MCA climate conditions on the Southern Tibetan Plateau were found to be generally similar to those in the south-eastern and Northwestern Tibetan Plateau areas, but anti-phase with those in the Southwestern and Eastern Tibetan Plateau areas. The variation of dry and wet climate over the Southern Tibetan Plateau in the past two thousand years may be related to the intensity changes of Indian monsoon and westerlies, the seasonal movement of westerly jet over the Tibetan Plateau, and the intensity changes of evapotranspiration.

Case series of COVID-19 patients from the Qinghai-Tibetan Plateau Area in China.

BACKGROUNDCoronavirus disease 2019 (COVID-19) is a serious infection caused by the new coronavirus severe acute respiratory syndrome coronavirus 2. The disease was first identified in December 2019 and has caused significant morbidity and mortality worldwide. AIMTo explore the clinical characteristics and treatments for COVID-19 in the Qinghai-Tibetan Plateau Area in China.METHODSWe retrospectively analyzed the blood cell counts (neutrophils and lymphocytes), blood gas analysis, and thoracic computed tomography changes of patients from Qinghai Province before, during, and after treatment (January 23, 2020 to February 21, 2020). In addition, we summarized and analyzed the information of critical patients. All data were analyzed using SPSS 17.0 (SPSS Inc., Chicago, IL, United States). The quantitative and count variables are represented as the mean ± SD and n (%), respectively.RESULTSThe main symptoms and signs of patients with COVID-19 were fever, dry cough, cough with phlegm, difficulty breathing, and respiratory distress with a respiration rate ≥ 30 times/min, finger oxygen saturation ≤ 93% in the resting state, and oxygenation index less than 200 but greater than 100 (after altitude correction). Eighteen patients with COVID-19, of whom three were critical, and the others were in a mild condition, were included. The main manifestations included fever, dry cough, and fatigue. Three patients developed difficulty breathing and had a fever. They were eventually cured and discharged. Adjuvant examinations showed one case with reduced white cell count (6%) (< 4 × 109/L), six with reduced count of lymphocytes (33%) (< 0.8 × 109/L), and one with abnormal blood glucose level. All 18 patients were discharged, and no death occurred.CONCLUSIONOur findings provide critical insight into assessing the clinical diagnosis and treatment for COVID-19 in the Tibetan plateau area.

Crustal azimuthal anisotropy and deformation beneath the northeastern Tibetan Plateau and adjacent areas: Insights from receiver function analysis

We present crustal azimuthal anisotropy measurements at 246 stations by fitting the sinusoidal moveout of P-to-S receiver functions to infer crustal deformation field in the northeastern (NE) Tibetan Plateau and adjacent areas. The dominant orientation of the observed crustal anisotropy shows a systematic spatial variation: NW-SE in the NE Tibetan Plateau and western Alxa Block, nearly NE-SW in the eastern Alxa Block and Yinchuan-Hetao Graben, and E-W in the eastern portion of the Western Qinling Terrane. The magnitude of crustal anisotropy varies from 0.15 to 0.75 s with an average of 0.36 ± 0.11 s. Fault parallel crustal anisotropy with large magnitudes observed in the NE Tibetan Plateau provides independent constraints on the lateral extent of the deformation zone associated with the faults. The observed spatial distribution of crustal anisotropy, when combined with previous crustal velocity and Poisson's ratio measurements, implies that channel flow in the middle-to-lower crust is unlikely to exist beneath the NE Tibetan Plateau. The main characteristics of crustal anisotropy observed in the western Alxa Block are similar to areas affected by the Indo-Eurasian collision, while those observed in the eastern Alxa Block are comparable to the stable North China Craton.

Sedimentary basin evolution and its implications for outward expansion of the northeastern Tibetan Plateau: Insights from the Tongxin Basin, China

The basin history of the northeastern Tibetan Plateau provides an ideal record for understanding the tectonic evolution of the plateau. We present high-resolution magnetostratigraphy and cosmogenic 10Be/26Al burial chronology from the Tongxin Basin in the Arcuate Ranges area in the northeastern Tibetan Plateau and reconstruct a long depositional history ranging from >21.7 to 4.6 Ma. Our new chronologic data suggest that a broad N-S-trending elongated basin existed during the Late Oligocene-Early Miocene (>21.7–16.5 Ma). WNW-trending faulting initiated at ca. 16.5 Ma and resulted in the formation of some fault-bounded basins outward from the western margin of the broad basin, but did not strongly affect the deposition within the basin region. Subsequently, intense northeastward compression elevated both WNW- and NWN-trending mountain ranges at ca. 7.6 Ma. Thrust-induced surface uplift elevated basin sediments and formed piggy-back basins in the hanging-wall blocks, reflecting the northeastward expansion of the northeastern Tibetan Plateau.

Microbiome analysis reveals soil microbial community alteration with the effect of animal excretion contamination and altitude in Tibetan Plateau of China

The fertile forages in the Tibetan Plateau provide natural conditions for animal husbandry, whereas it is still unclear that whether animal excretion can result in the alteration of soil microbial community. Therefore, this study was performed to investigate the impact of animal excretion contamination and land altitude on the soil microbial community in different grazing areas of Tibetan Plateau. A total of 1160,190 high-quality valid sequences and 25,478 operational taxonomic units were achieved from 18 samples at three different altitude sites (Linzhi, Rikaze and Shannan). Here, we found excremental contamination did not alter the richness and diversity of soil microbial community, but it resulted in a significant alteration in the proportion of some bacteria. Specifically, the proportion of Proteobacteria in the LZa was obviously increased, whereas Gemmatimonadetes was significantly decreased as compared to LZe. Moreover, significant difference can also be observed in Verrucomicrobia between RKZe and RKZa. Remarkably, we also found that excremental contamination significantly decreased the abundance of some bacterial genera, such as Sphingopyxis, Polycyclovorans, Singulisphaera Cohnella, Polycyclovorans, Defluviicoccus, and Arthrobacter, which were closely related to soil health, pollutant degradation, and nutrient metabolism. Importantly, excremental contamination increased the proportion of harmful and beneficial bacteria in soil, such as the percentage of Acidibacter, Gemmatimonadaceae and Pajaroellobacter increased, while the ratio of Pontibacter, Flavisolibacter, Parasegetibacter, and Niastella decreased. Remarkably, soil samples collected from different altitude sites also displayed different soil microbial community structures. Our results demonstrated that excremental contamination could alter the soil microbial community structure and affect the normal function of the soil by affecting the proportion of harmful bacteria to beneficial bacteria. Moreover, this study can also provide a theoretical basis for the establishment of a supervision system for soil quality in Tibet.

The Effects of Terrain Factors and Cultural Landscapes on Plateau Forest Distribution in Yushu Tibetan Autonomous Prefecture, China

The Yushu Tibetan Autonomous Prefecture is a typical Tibetan plateau area, and its ecological environment is very fragile. It is necessary to explore the terrain and cultural factors for the protection of the local ecological environment. We mainly investigated and quantified the effect of terrain factors and two typical plateau cultural landscapes (temples and villages) on the spatiotemporal variation characteristics of four types of forest landscape in the Yushu Tibetan Autonomous Prefecture from 1990 to 2015 using remote sensing (RS) and geographic information system (GIS) technology. The results showed that, under the influence of terrain factors, forest landscapes were only distributed in places with an altitude of 5055 meters above sea level (masl) to 6300 masl, with a slope of 0–27°, and the largest distribution area was shrubbery. The area of the forest decreased with the increase in altitude, and it first rose and then decreased with the increase in slope. Regression analysis results showed that the influence of altitude on closed forest land and open forest land followed a polynomial function, while that on shrubbery followed a logarithmic function, and the impact of slope on the three forest landscapes followed the amplitude version of a Gaussian peak function. Considering cultural factors, temples and villages did not determine the forest distribution in the same way as natural factors do, but they motivated the amount of forest over spatiotemporal scales. Temples had a greater influence on forest protection than villages, and this positive impact was stronger within 6 km. The area of forest distributed around the temple accounts for more than 45.67% of the total forest area, and this area has not changed significantly in 25 years. In summary, altitude and slope affect the natural distribution of the forest, and temples affect the scale of forest distribution. These results reveal the impact of terrain factors and cultural landscapes on forest distribution and could motivate an even more effective management for sustainable forest development.

A randomised trial on the therapeutic effectiveness of bronchoalveolar lavage under fiberoptic bronchoscopy in patients with severe lung infection living in the Tibetan plateau area.

People living in plateau areas are prone to upper respiratory tract infections and secondary lung infections. The current study aimed to explore the effects of bronchoalveolar lavage under fiberoptic bronchoscope for the treatment of patients with severe pulmonary infection living in plateau areas. 148 patients with severe lung infection admitted to the intensive care unit of Shigatse People's Hospital (Shigatse, Tibet Autonomous Region, China) between July 2019 and January 2021 were enrolled. Patients were randomly assigned to the observational group or the control group. For all patients, basic clinical data including sex, age, body mass index (BMI), blood pressure, diabetes history, stroke history, presence or absence of chronic obstructive pulmonary disease, lung infection (gram-positive bacterial infection, gram-negative bacterial infection, fungal infection, acute lung abscess), surgical history, and postoperative inhalation injury. were collected. The control group received conventional treatment, and the observational group received bronchoalveolar lavage under fiberoptic bronchoscopy. Pearson's correlation was used to analyze the correlations between bronchoalveolar lavage under fiberoptic bronchoscopy and inflammatory factors levels. Logistic regression was used to investigate the correlation between bronchoalveolar lavage under fiberoptic bronchoscopy and the effectiveness of the treatment. Before treatment, no significant difference existed in the basic data of the observational group and the control group. After treatment, the parameters of respiratory mechanics and inflammatory factors in the 2 groups were significantly improved compared with those before treatment (P<0.05). At the same time, in the observational group, the clinical parameters were significantly higher than those of the control group, and the levels of inflammatory factors were significantly lower than those of the control group (all P<0.05). After full adjustment for age, sex, BMI, gram-negative infection, diabetes, and acute lung abscess, compared with the control group, the therapeutic effectiveness in the observational group was increased by 23% (OR =1.23, 95% CI: 1.09-1.51, P=0.007). For patients with severe lung infection who are resident in high altitude areas, compared with conventional treatments, bronchoalveolar lavage under fiberoptic bronchoscopy can significantly improve chest, lung, and total dynamic compliance, as well as reduce the levels of the inflammatory factors procalcitonin (PCT) and transforming growth factor-β, thus increasing the effectiveness of the treatment.

Effects of climate change on the heating indices in central heating zone of China

This study investigated the impacts of the temperature change on the length of heating period (HL), the starting date (HS) and the ending date for heating (HE), and the heating degree-days (HDD) in the central heating zone of China. By using the outputs from regional climate model, the future changes of four heating indices were quantitatively assessed. The results show that the regional mean HL in the central heating zone exhibits a decreasing trend during 2006–2050 under RCP4.5 due to the later HS and the earlier HE, and the decreasing rate of HL is 1.9d/10a. The regional mean HDD significantly decreases at a rate of 63.2 °C·d/10a during 2006–2050. There are apparent differences in the responses of HL and HDD to temperature change in different regions. An obvious decrease of HL is observed in the south and the HDD significantly decreases in the Tibetan Plateau and northeast severe cold areas. These results suggest that different heating strategies should be adopted according to different climate conditions. Considering the present-day mean HDD, the energy-saving potential in the future is larger in the south while the energy consumption demand for heating is larger in the severe cold areas.

Geochronological study of biotite aegirine‐augite syenite in the Bengge area, Western Yunnan: An example of zircon U–Pb dating for alkalic rocks

The Bengge biotite aegirine‐augite syenite (BAS) is located in the southern part of Yidun Arc, eastern margin of the Tibetan Plateau area. It is an integral part of the Bengge ultrapotassic rocks (UPR), an alkalic complex mainly consisting of BAS, biotite pyroxene syenite (BPS), and biotite syenite (BS). Geochronological studies including zircon LA‐ICPMS U–Pb dating and biotite 40Ar/39Ar dating have been conducted on the Bengge BAS to constrain its emplacement age. The zircon U–Pb dating yields a wide range of ages from 209 ± 2 Ma to 239 ± 2 Ma, with the concordia 206Pb/238U age being 228 ± 8.9 Ma (MSWD = 0.13). Meanwhile, the biotite 40Ar/39Ar dating yields a plateau age of 205.7 ± 1.5 Ma. The whole‐rock Zr‐saturation temperature (Tzir‐sat) of the Bengge BAS has shown to be very low (86 ± 13°C to 634 ± 13°C), which is much lower than Ti‐in‐zircon temperature (&gt;758°C) of the zircons used for U–Pb dating. This indicates that the zircons in the Bengge BAS are inherited, and they were already present in the BAS melts before the melts became Zr‐saturated. Similarly, the Tzir‐sat of the Bengge BPS and BS are 346 ± 14°C ~ 549 ± 13°C and 281 ± 14°C ~ 525 ± 13°C, respectively, which is also too low for magmatic zircon crystallization in the melts. The inherited zircons of Bengge BAS have typical features of magmatic zircon, with high (Sm/La)N ratios (2.54–819), Ce/Ce* ratios (4.77–304) and low La concentration. Low εHf (T) values (−5.0 to 0.42) and high U/Yb (0.67–12.6) values imply that the inherited zircons (209–239 Ma) in the Benge BAS are derived from an early arc‐magma system of the Yidun Arc. The biotite 40Ar/39Ar dating constrains the Bengge BAS emplacement age at 205.7 ± 1.5 Ma, the time when the arc‐magma activity had ceased, and a regional geodynamic transition in the Yidun Arc from convergence to back‐arc spreading had started.

Inhalation exposure to size-segregated fine particles and particulate PAHs for the population burning biomass fuels in the Eastern Tibetan Plateau area

Indoor biomass burning produces large amounts of small particles and hazardous contaminants leading to severe air pollution and potentially high health risks associated with inhalation exposure. Personal samplers provide more accurate estimates of inhalation exposure. In this study, inhalation exposure to size-segregated particles and particulate polycyclic aromatic hydrocarbons (PAHs) for the biomass user was studied by deploying personal samplers. The study found that daily PM2.5 inhalation exposure level was as high as 121 ± 96 μg/m3, and over 84% was finer PM1.0. For PAHs, the exposure level was 113 ± 188 ng/m3, with over 77% in PM1.0. High molecular weight PAHs with larger toxic potentials enriched in smaller particles resulting in much high risks associated with PAHs inhalation exposure. Indoor exposure contributed to ~80% of the total inhalation exposure as a result of high indoor air pollution and longer residence spent indoor. The highest exposure risk was found for the male smoker who conducted cooking activities at home.

Impact of C factor of USLE technique on the accuracy of soil erosion modeling in elevated mountainous area (case study: the Tibetan plateau)

The soil loss caused by rainfall-runoff process is a global issue which can decrease the lands fertility and increase the flood hazards. There are many different empirical relationships and numerical methods available for soil loss estimation. One of the most commonly used methods is the Universal Soil Loss Equation (USLE), which is widely used to estimate the amount of annual rill erosion. The main aim of this paper was to evaluate the accuracy and applicability of the USLE method in the estimation of soil loss in elevated and rocky mountainous areas of Tibetan plateau. To do this, some of the observed and modeled soil loss data that were available in some Chinese researches, were selected. Land slope, soil type, land cover, Normalized Difference Vegetation Index (NDVI), aspect, monthly and annual rainfall and runoff maps from GIS were derived and investigated to calculate the USLE parameters. The results showed that the accuracy of the USLE model was decreased significantly in regions with high soil loss risk due to ignoring the rock properties and snow cover in K parameter. Also, the results showed that parameters which can decrease the soil loss significantly such as rock fragments content and low height vegetation have to be considered in NDVI calculation. Hence, it is recommended to improve the accuracy of the model by adjusting C factor for elevated mountainous areas based on the rock properties and snow cover which can be derived from the remote sensing maps.

Improve the Accuracy of Water Storage Estimation—A Case Study from Two Lakes in the Hohxil Region of North Tibetan Plateau

Lake water storage is essential information for lake research. Previous studies usually used bathymetric data to acquire underwater topography by interpolation method, and to therefore estimate water storage. However, due to the large area of Tibetan Plateau (TP) lakes, the method of bathymetry was challenging to cover the whole region of one lake, and the accuracy of the underwater topography, in which no bathymetric data covered, was low, which resulted in a comparatively large error of lake water storage estimation and its change. In this study, we used Shuttle Radar Topography Mission (SRTM) and in situ bathymetric data to establish the underwater topography of Hohxil Lake (HL) and Lexiewudan Lake (LL) in the Hohxil Region of North TP and estimate and analyzed the changes of lake level and water storage. The results showed HL and LL’s water storage was 5.12 km3 and 5.31 km3 in 2019, respectively, and their level increased by 0.5 m/y and 0.57 m/y during 2003−2018, respectively. They were consistent with those (0.5 m/y and 0.5 m/y) from altimetry data, and they were much more accurate than those results (0.077 m/y and 0.156 m/y) from bathymetric data. These findings indicated that this method could improve the accuracy of lake water storage and change estimation. We estimated water storage of two lakes by combining with multitemporal Landsat images, which had doubled since 1976. Our results suggested that the increasing precipitation may dominate the lake expansion by comparing with the change of temperature and precipitation and the increasing glacial meltwater contributed approximately 4.8% and 10.7% to lake expansion of HL and LL during 2000–2019 based on the glacier mass balance data, respectively.

Sources and light absorption characteristics of water-soluble organic carbon (WSOC) of atmospheric particles at a remote area in inner Himalayas and Tibetan Plateau

Water-soluble organic carbon (WSOC) is an important component of carbonaceous aerosols. Increasing evidences show that WSOC absorbs and scatters sunlight in the atmosphere, which is one of the key components of climate change. Despite numbers of related studies, understanding of basic characteristics of WSOC is limited at remote region, such as the Himalayas and Tibetan Plateau (HTP), one of the remotest regions in the world with weak local anthropogenic activities. In this study, we conducted a year-round investigation of multiple aerosol species at Nam Co, a pristine station in inner part of the HTP. The results showed that the annual mean concentrations of PM2.5 and its WSOC were 8.9 ± 5.4 μg m−3 and 249 ± 111 ng m−3, respectively, which was among the lowest values in the HTP, representing a clean environment. WSOC of PM2.5 and total suspended particle (TSP) samples were mainly derived from combustion emissions and fine particle of local surface soil, respectively, indicating significant contribution of local sources of the HTP to TSP samples. Similarly, due to the influence of surface soil, respective absorption per mass of WSOC at 365 nm (α/ρWSOC) of TSP (1.74 ± 0.94 m2 g−1) was significantly higher than that of PM2.5 (1.22 ± 0.43 m2 g−1). Seasonally, high and low WSOC concentrations and α/ρWSOC values appeared at non-monsoon and monsoon periods, respectively. This study provides observational constraints for related researches such as modelling of the environmental impact of WSOC in the HTP.

Insights into a remote cryosphere: a multi-method approach to assess permafrost occurrence at the Qugaqie basin, western Nyainqêntanglha Range, Tibetan Plateau

Abstract. Permafrost as a climate-sensitive parameter and its occurrence and distribution play an important role in the observation of global warming. However, field-based permafrost distribution data and information on the subsurface ice content in the large area of the southern mountainous Tibetan Plateau (TP) are very sparse. Existing models based on boreholes and remote sensing approaches suggest permafrost probabilities for most of the Tibetan mountain ranges. Field data to validate permafrost models are generally lacking because access to the mountain regions in extreme altitudes is limited. The study provides geomorphological and geophysical field data from a north-orientated high-altitude catchment in the western Nyainqêntanglha Range. A multi-method approach combines (A) geomorphological mapping, (B) electrical resistivity tomography (ERT) to identify subsurface ice occurrence and (C) interferometric synthetic aperture radar (InSAR) analysis to derive multi-annual creeping rates. The combination of the resulting data allows an assessment of the lower occurrence of permafrost in a range of 5350 and 5500 m above sea level (a.s.l.) in the Qugaqie basin. Periglacial landforms such as rock glaciers and protalus ramparts are located in the periglacial zone from 5300–5600 m a.s.l. The altitudinal periglacial landform distribution is supported by ERT data detecting ice-rich permafrost in a rock glacier at 5500 m a.s.l. and ice lenses around the rock glacier (5450 m a.s.l.). The highest multiannual creeping rates up to 150 mm yr−1 are typically observed on these rock glaciers. This study closes the gap of unknown state of periglacial features and potential permafrost occurrence in a high-elevated basin in the western Nyainqêntanglha Range (Tibetan Plateau).

Petrology and metamorphism of glaucophane eclogites in Changning-Menglian suture zone, Bangbing area, southeast Tibetan Plateau: An evidence for Paleo-Tethyan subduction

High/ultrahigh-pressure (HP/UHP) metamorphic complexes, such as eclogite and blueschist, are generally regarded as significant signature of paleo-subduction zones and paleo-suture zones. Glaucophane eclogites have been recently identified within the Lancang Group characterized by accretionary mélange in the Changning-Menglian suture zone, at Bangbing in the Shuangjiang area of southeastern Tibetan Plateau. The authors report the result of petrological, mineralogical and metamorphism investigations of these rocks, and discuss their tectonic implications. The eclogites are located within the Suyi blueschist belt and occur as tectonic lenses in coarse-grained garnet muscovite schists. The major mineral assemblage of the eclogites includes garnet, omphacite, glaucophane, phengite, clinozoisite and rutile. Eclogitic garnet contains numerous inclusions, such as omphacite, glaucophane, rutile, and quartz with radial cracks around. Glaucophane and clinozoisite in the matrix have apparent optical and compositional zonation. Four stages of metamorphic evolution can be determined: The prograde blueschist facies (M₁), the peak eclogite facies (M₂), the decompression blueschist facies (M₃) and retrograde greenschist facies (M₄). Using the Grt-Omp-Phn geothermobarometer, a peak eclogite facies metamorphic <i>P-T</i> condition of 3000–3270 MPa and 617–658°C was determined, which is typical of low-temperature ultrahigh-pressure metamorphism. The comparison of the geological characteristics of the Bangbing glaucophane eclogites and the Mengku lawsonite-bearing retrograde eclogites indicates that two suites of eclogites may have formed from significantly different depths or localities to create the tectonic mélange in a subduction channel during subduction of the Triassic Changning-Menglian Ocean. The discovery of the Bangbing glaucophane eclogites may represent a new oceanic HP/UHP metamorphic belt in the Changning-Menglian suture zone.

Progress and Challenges in Studying Regional Permafrost in the Tibetan Plateau Using Satellite Remote Sensing and Models

Recent climate change has induced widespread soil thawing and permafrost degradation in the Tibetan Plateau. Significant advances have been made in better characterizing Tibetan Plateau soil freeze/thaw dynamics, and their interaction with local-scale ecohydrological processes. However, factors such as sparse networks of in-situ sites and short observational period still limit our understanding of the Tibetan Plateau permafrost. Satellite-based optical and infrared remote sensing can provide information on land surface conditions at high spatial resolution, allowing for better representation of spatial heterogeneity in the Tibetan Plateau and further infer the related permafrost states. Being able to operate at “all-weather” conditions, microwave remote sensing has been widely used to retrieve surface soil moisture, freeze/thaw state, and surface deformation, that are critical to understand the Tibetan Plateau permafrost state and changes. However, coarse resolution (&amp;gt;10 km) of current passive microwave sensors can add large uncertainties to the above retrievals in the Tibetan Plateau area with high topographic relief. In addition, current microwave remote sensing methods are limited to detections in the upper soil layer within a few centimetres. On the other hand, algorithms that can link surface properties and soil freeze/thaw indices to permafrost properties at regional scale still need improvements. For example, most methods using InSAR (interferometric synthetic aperture radar) derived surface deformation to estimate active layer thickness either ignore the effects of vertical variability of soil water content and soil properties, or use site-specific soil moisture profiles. This can introduce non-negligible errors when upscaled to the broader Tibetan Plateau area. Integrating satellite remote sensing retrievals with process models will allow for more accurate representation of Tibetan Plateau permafrost conditions. However, such applications are still limiting due to a number of factors, including large uncertainties in current satellite products in the Tibetan Plateau area, and mismatch between model input data needs and information provided by current satellite sensors. Novel approaches to combine diverse datasets with models through model initialization, parameterization and data assimilation are needed to address the above challenges. Finally, we call for expansion of local-scale observational network, to obtain more information on deep soil temperature and moisture, soil organic carbon content, and ground ice content.

Morphological and metric criteria for identifying postcranial skeletal remains of modern and archaeological Caprinae and Antilopinae in the northeast Tibetan Plateau and adjacent areas

AbstractOsseous remains of medium‐sized Caprinae and Antilopinae are often found in late Quaternary archaeological sites in the northeast Tibetan Plateau and adjacent areas, but their accurate taxonomic identification poses considerable problems to zooarchaeologists. Building on previous osteomorphological studies and a statistically significant number of modern comparatives, this study presents diagnostic morphological features and metric data of selected skeletal elements, enabling taxonomic classification of six medium‐sized wild bovid genera widely distributed across the region, that is, Blue sheep (Pseudois nayaur), Argali (Ovis ammon), Serow (Capricornis sp.), Goral (Naemorhedus sp.) and two genera of Antilopinae (Gazella, Procapra), as well as domestic sheep (O. aries) and goats (Capra hircus). A blind test showed that using these anatomical criteria on modern specimens allowed separating unequivocally all taxa in the case of the distal humerus, but a lesser degree of confidence in the case of the distal metapodials. Applying these criteria to archaeological specimens from the prehistoric northeast Tibetan Plateau, we conclude that distal humeri can be confidently assigned taxonomically by applying a stepwise approach, whereas in distal metacarpals and metatarsals, the probabilistic approach is proving more promising for classifying specimens correctly.

Chemical characterization and sources of PM2.5 at a high-alpine ecosystem in the Southeast Tibetan Plateau, China

Abstract The study of atmospheric chemical compositions in remote areas is of great significance for understanding the biogeochemical impact of atmospheric dry deposition on ecosystems. In this study, a total of 50 p.m.2.5 samples were collected at a high alpine forest of Mt. Gongga, Eastern Tibetan Plateau from May 2015 to May 2016 to investigate the characteristics of PM2.5 mass concentration and its major compositions including elemental carbon (EC), organic carbon (OC), and 24 trace elements. The average PM2.5 mass concentration was 17.19 ± 8.81 μg/m3, which was at an intermediate level compared with other areas of Tibetan Plateau. The yearly average concentrations of OC and EC were 2.98 ± 1.95 and 0.43 ± 0.33 μg/m3, accounting for 19.49% and 2.51% of PM2.5 mass, respectively, and the sums of the total concentrations of the 24 analyzed trace elements were 3.70 ± 0.80 μg/m3, accounting 27% of PM2.5 mass concentration. PM2.5, EC and OC showed the higher concentrations and larger fluctuation in the dry season (October 2015 to May 2016) compared with those in the wet season (June 2015 to September 2015), which was attributed to the multiple factors including the increases of biomass burning and fossil fuel emissions, the relatively shallow boundary layer height and lower temperature, and the less precipitation. Two distinct seasonal patterns were observed for the 24 analyzed trace elements in PM2.5: the crustal-derived trace elements like Fe, Al, Mn and Sr showed the higher concentrations in the wet season, while anthropogenic-derived elements such as Cd, Pb, Ni and Zn exhibited the higher level during the dry season. Six sources were identified for PM2.5 at Mt. Gongga with the application of the positive matrix factorization (PMF). Biomass burning (27.06%) and crustal source (26.93%) were the two main sources, followed by secondary formation (16.41%), traffic-related source (12.89%), coal burning (10.57%) and industrial metallurgical process (6.15%). Finally, it was proposed that the atmospheric acidic processing could not only promote the dissolution of Fe, but also enhance the solubility of the other trace elements in the atmosphere during the transport. Accordingly, this would increase the bioavailability and/or toxicity to the biotic and plants.

The coupling impact of climate change on streamflow complexity in the headwater area of the northeastern Tibetan Plateau across multiple timescales

The streamflow from the headwater areas of the Tibetan Plateau (TP) provides critical support for downstream regions, yet understanding of the streamflow complexity on the TP, which is essential for hydrological modeling and water resource management, remains scarce. This study aims to measure streamflow complexity in the headwater areas of the TP and investigate the coupling effects of climatic variables (i.e., precipitation and air temperature) on the streamflow complexity across multiple timescales. Using daily streamflow records, we employ permutation entropy as the measure of annual streamflow complexity in the upper Heihe River (UHR) watershed in the northeastern TP from 1960 to 2014. Additionally, wavelet coherence is applied to evaluate the impact of climate (i.e., precipitation and temperature) change. Our results show: (1) due to climate change, streamflow complexity has significantly increased since 1972 in the UHR watershed; (2) the periods of warmer and wetter weather have a longer-term influence on streamflow complexity. Specifically, before 1972, dryer, colder weather in the TP would significantly affect the complexity of the streamflow every three to four years, but after that date, these climatic events occurred less frequently, with gaps of between eight and twelve years, during which the weather was much warmer and wetter; and (3) the influence of precipitation on the streamflow complexity decreased, while that of air temperature increased. Therefore, the impact of climate change on streamflow complexity relating to the dynamic structure of streamflow should be regarded as significant to the work of hydrologists and water resource management agencies.