Academic literature on the topic 'Tibetan area aging'
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Journal articles on the topic "Tibetan area aging"
1
Ran, Liang, Zhaoze Deng, Yunfei Wu, Jiwei Li, Zhixuan Bai, Ye Lu, Deqing Zhuoga, and Jianchun Bian. "Measurement report: Vertical profiling of particle size distributions over Lhasa, Tibet – tethered balloon-based in situ measurements and source apportionment." Atmospheric Chemistry and Physics 22, no. 9 (May 13, 2022): 6217–29. http://dx.doi.org/10.5194/acp-22-6217-2022.
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Abstract. In situ measurements of vertically resolved particle size distributions based on a tethered balloon system were carried out for the first time in the highland city of Lhasa over the Tibetan Plateau in summer 2020, using portable optical counters for the size range of 0.124–32 µm. The vertical structure of 112 aerosol profiles was found to be largely shaped by the evolution of the planetary boundary layer (PBL), with a nearly uniform distribution of aerosols within the daytime mixing layer and a sharp decline with the height in the shallow nocturnal boundary layer. During the campaign, mass concentrations of particulate matter smaller than 2.5 µm in aerodynamic diameter (PM2.5) within the PBL ranged from 0.5 to 12.0 µg m−3, with an average and standard deviation of 3.4 ± 2.3 µg m−3, almost 4 times the amount in the free troposphere (FT), which was rarely affected by surface anthropogenic emissions. Though there was a lower level of particle mass in the residual layer (RL) than in the PBL, a similarity in particle mass size distributions (PMSDs) suggested that particles in the RL might be of the same origin as the particles in the PBL. This was also consistent with the source apportionment analysis based on the PMSDs. In total, three distinct modes were observed in the PMSDs for the PBL and the RL. One mode was exclusively coarse particles up to roughly 15 µm, peaking around 5 µm. More than 50 % of total particle mass was often contributed by coarse-mode particles in this area, which was thought to be associated with local dust resuspension. The mode peaking over 0.5–0.7 µm was representative of biomass burning on religious holidays and was found to be most pronounced on holiday mornings. The contribution from the religious burning factor rose from about 25 % on non-holidays to nearly 50 % on holiday mornings. The mode dominated by particles smaller than 0.3 µm was thought to be associated with combustion-related emissions and/or secondary aerosol formation. In the FT coarse mode, particles only accounted for less than 10 % of the total mass, and particles larger than 5 µm were negligible. The predominant submicron particles in the FT might be related to secondary aerosol formation and the aging of existing particles. To give a full picture of aerosol physical and chemical properties and better understand the origin and impacts of aerosols in this area, intensive field campaigns involving measurements of vertically resolved aerosol chemical compositions in different seasons would be highly encouraged in the future.
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Zhou, Guomin. "Experimental study on long-term aging of photovoltaic modules in plateau environment." E3S Web of Conferences 352 (2022): 03006. http://dx.doi.org/10.1051/e3sconf/202235203006.
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There are some studies on the long-term aging power attenuation of components in China, but in Tibet, an area with high altitude and high ultraviolet intensity, there are no specific data and research materials on whether the attenuation factor of component power is the same as that in the mainland, whether the high altitude environment has an impact on the service life of components, and how the impact law is. The law and degree of aging attenuation of modules are an important basis for the maintenance of photovoltaic power stations. Therefore, it is very meaningful to study the long-term aging attenuation of photovoltaic modules in high-altitude areas.
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Guo, Dong Feng, Xiao Jun Ma, Xiao Yan Ma, and Jian Hong Fang. "Effect of Ultraviolet Aging on Rheological Properties and Microstructure of Rubber Asphalt in High Altitude Area." Materials Science Forum 1079 (December 26, 2022): 179–85. http://dx.doi.org/10.4028/p-834hjr.
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High altitude and strong ultraviolet radiation in Qinghai Tibet Plateau induces the brittleness and hardening of asphalt, which leads to temperature cracks, pits and other diseases of asphalt pavement. In this paper, the accelerated UV aging test of rubber asphalt was carried out by simulating the UV radiation intensity in Xining, Qinghai Province, and the rheological properties and microstructure changes of rubber asphalt were analyzed. The results show that the complex modulus of rubber asphalt increases exponentially with the extension of UV aging time. The phase angle of rubber asphalt decreases linearly with UV aging, and the deformation recovery performance of rubber asphalt increases; UV radiation has the most significant effect on the micro morphology of rubber asphalt. With the further extension of UV aging time, micro cracks are formed in rubber asphalt, and the low-temperature crack resistance and fatigue failure resistance of rubber asphalt are gradually reduced.
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Wu, Wei, Qingsheng Liu, He Li, and Chong Huang. "Spatiotemporal Distribution of Heatwave Hazards in the Chinese Mainland for the Period 1990–2019." International Journal of Environmental Research and Public Health 20, no. 2 (January 14, 2023): 1532. http://dx.doi.org/10.3390/ijerph20021532.
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Heatwaves occur frequently in summer, severely harming the natural environment and human society. While a few long-term spatiotemporal heatwave studies have been conducted in China at the grid scale, their shortcomings involve their discrete distribution and poor spatiotemporal continuity. We used daily data from 691 meteorological stations to obtain torridity index (TI) and heatwave index (HWI) datasets (0.01°) in order to evaluate the spatiotemporal distribution of heatwaves in the Chinese mainland for the period of 1990–2019. The results were as follows: (1) The TI values rose but with fluctuations, with the largest increase occurring in North China in July. The areas with hazard levels of medium and above accounted for 22.16% of the total, mainly in the eastern and southern provinces of China, South Tibet, East and South Xinjiang, and Chongqing. (2) The study areas were divided into four categories according to the spatiotemporal distribution of hazards. The “high hazard and rapidly increasing” and “low hazard and continually increasing” areas accounted for 8.71% and 41.33% of the total, respectively. (3) The “ten furnaces” at the top of the provincial capitals were Zhengzhou, Nanchang, Wuhan, Changsha, Shijiazhuang, Nanjing, Hangzhou, Haikou, Chongqing, and Hefei. While the urbanization level and population aging in the developed areas were further increased, the continuously increasing heatwave hazard should be fully considered.
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An, Yingying, Xianhong Meng, Lin Zhao, Zhaoguo Li, Shaoying Wang, Lunyu Shang, Hao Chen, Shihua Lyu, Guangwei Li, and Yingsai Ma. "Performance of GLASS and MODIS Satellite Albedo Products in Diagnosing Albedo Variations during Different Time Scales and Special Weather Conditions in the Tibetan Plateau." Remote Sensing 12, no. 15 (July 31, 2020): 2456. http://dx.doi.org/10.3390/rs12152456.
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Surface albedo is a crucial parameter in accurately and quantitatively estimating energy and water budget on the Tibetan Plateau (TP) and is also one of the largest radiative uncertainties in land surface modelling attempts. Based on an 8-year ground-based observation of the surface albedo over typical alpine meadows at Maqu and Maduo sites in the eastern TP, the performance of surface albedo products of Global LAnd Surface Satellite (GLASS) and Moderate Resolution Imaging Spectroradiometer (MODIS) in describing albedo variations at daily, 8-day, seasonal timescales, and during different special weather conditions were analyzed. Compared with the ground-based observation in Maqu, the 8-day albedo products from GLASS and MCD43B3 present maximum negative biases of −0.030 and −0.027 at Maqu, respectively. The black-sky albedo (BSA) of GLASS product coincides well with the ground-based observation in Maduo, with root mean square error (RMSE) of 0.092 and correlation coefficient (R) of 0.833, whereas that of MCD43B3 had an RMSE of 0.072 and R of 0.752. However, they are underestimated when the albedo is greater than 0.4. At the seasonal timescale, the BSA of GLASS and MCD43B3 underestimated the ground-based observation of Maqu by 0.015 in summer, while their white-sky albedo (WSA) are slightly overestimated and closer to the ground-based observation. In daily timescale, the response of surface albedo to soil moisture is different in semihumid and semiarid areas in summer. For both sites, the blue-sky-albedo of MCD43A3 has better agreement with the ground-based observation than GLASS and MCD43B3, as it improves the temporal resolution and calculates the albedo by weighting multiple observations within 16 days to be closer to the actual surface. However, even MCD43A3 could not capture the slowdown processes of albedo changes resulted by small snowfall processes or the snow aging due to cloud cover and inversion algorithms.
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Gul, Chaman, Siva Praveen Puppala, Shichang Kang, Bhupesh Adhikary, Yulan Zhang, Shaukat Ali, Yang Li, and Xiaofei Li. "Concentrations and source regions of light-absorbing particles in snow/ice in northern Pakistan and their impact on snow albedo." Atmospheric Chemistry and Physics 18, no. 7 (April 12, 2018): 4981–5000. http://dx.doi.org/10.5194/acp-18-4981-2018.
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Abstract. Black carbon (BC), water-insoluble organic carbon (OC), and mineral dust are important particles in snow and ice which significantly reduce albedo and accelerate melting. Surface snow and ice samples were collected from the Karakoram–Himalayan region of northern Pakistan during 2015 and 2016 in summer (six glaciers), autumn (two glaciers), and winter (six mountain valleys). The average BC concentration overall was 2130 ± 1560 ng g−1 in summer samples, 2883 ± 3439 ng g−1 in autumn samples, and 992 ± 883 ng g−1 in winter samples. The average water-insoluble OC concentration overall was 1839 ± 1108 ng g−1 in summer samples, 1423 ± 208 ng g−1 in autumn samples, and 1342 ± 672 ng g−1 in winter samples. The overall concentration of BC, OC, and dust in aged snow samples collected during the summer campaign was higher than the concentration in ice samples. The values are relatively high compared to reports by others for the Himalayas and the Tibetan Plateau. This is probably the result of taking more representative samples at lower elevation where deposition is higher and the effects of ageing and enrichment are more marked. A reduction in snow albedo of 0.1–8.3 % for fresh snow and 0.9–32.5 % for aged snow was calculated for selected solar zenith angles during daytime using the Snow, Ice, and Aerosol Radiation (SNICAR) model. The daily mean albedo was reduced by 0.07–12.0 %. The calculated radiative forcing ranged from 0.16 to 43.45 W m−2 depending on snow type, solar zenith angle, and location. The potential source regions of the deposited pollutants were identified using spatial variance in wind vector maps, emission inventories coupled with backward air trajectories, and simple region-tagged chemical transport modeling. Central, south, and west Asia were the major sources of pollutants during the sampling months, with only a small contribution from east Asia. Analysis based on the Weather Research and Forecasting (WRF-STEM) chemical transport model identified a significant contribution (more than 70 %) from south Asia at selected sites. Research into the presence and effect of pollutants in the glaciated areas of Pakistan is economically significant because the surface water resources in the country mainly depend on the rivers (the Indus and its tributaries) that flow from this glaciated area.
7
Arima, Hiroaki, Masayuki Nakano, Sweta Koirala, Hiromu Ito, Basu Dev Pandey, Kishor Pandey, Takayuki Wada, and Taro Yamamoto. "Unique hemoglobin dynamics in female Tibetan highlanders." Tropical Medicine and Health 49, no. 1 (January 4, 2021). http://dx.doi.org/10.1186/s41182-020-00289-6.
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Abstract Background Tibetan highlanders have adapted to hypoxic environments through the development of unique mechanisms that suppress an increase in hemoglobin (Hb) concentration even in high-altitude areas. Hb concentrations generally decrease with increasing age. However, in the highlands, chronic altitude sickness is known to occur in the elderly population. To investigate how aging in a hypoxic environment affects Hb levels in Tibetan highlanders, we focused on the Mustang people, who live above 3500 m. We tried to clarify the pure relationship between aging and Hb levels in a hypoxic environment. Results We found that the Hb concentration increased with increasing age in females but not in males. Multivariate analysis showed that age, pulse pressure, the poverty index, and vascular diameter were strongly correlated with the Hb concentration. Conclusions We found unique Hb dynamics among female Tibetan highlanders. As seen in these Hb dynamics, there may be sex-based differences in the adaptive mechanism in Tibetan highlanders.
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Zhang, Haotian, Pengfei Tian, Chenliang Kang, Yumin Guo, Zeren Yu, Gefei Lu, Chenguang Tang, et al. "Regional organic matter and mineral dust are the main components of atmospheric aerosols over the Nam Co station on the central Tibetan Plateau in summer." Frontiers in Environmental Science 10 (December 2, 2022). http://dx.doi.org/10.3389/fenvs.2022.1055673.
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The transport of air pollutants from areas surrounding the Tibetan Plateau (TP) has recently been studied. However, the major sources of atmospheric total suspended particulate matter (TSP) on the central TP remain unclear due to a lack of in-situ observations on aerosol physico-chemical properties. Therefore, to quantitatively investigate the physico-chemical properties and reveal the major sources of atmospheric aerosols, a comprehensive field campaign was conducted at the site of Nam Co from August 6 to September 11, 2020. Aerosol loading was low during the campaign with average TSP mass concentration, scattering coefficient at 550 nm, and absorption coefficient at 670 nm being 10.11 ± 5.36 μg m−3, 1.71 ± 1.36 Mm−1, and 0.26 ± 0.20 Mm−1, respectively. Organic matter (63.9%) and mineral dust (27.8%) accounted for most of the TSP mass concentrations. The average scattering Ångström exponent of 0.59 ± 0.14 reflected the influence of mineral dust, and the elemental fractions and the results of enrichment factor illustrated that crustal materials were the main contributors of mineral dust. The organic to elemental carbon ratio of 15.33 is probably caused by the aging that occurs during the transport of aerosols. The strong correlation between organic carbon and Ca2+ and the results of the electron microscopy analysis of single particles indicated that organic carbon and mineral dust had the same sources; however, the weak relation between mineral dust and wind speed indicated that local wind erosion was not the main contributor to the mineral dust. The potential source contribution function further illustrated that the summertime TSP in the central TP was mainly characterized by background biomass and mineral dust aerosols originating regionally from the ground within the TP.
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Yang, Qingwen, Xiangjun Pei, and Cheng Fu. "Effect of Polymer Mixtures on Physical-Chemical Properties of Sandy Soil and Plant Growth." Frontiers in Ecology and Evolution 10 (June 6, 2022). http://dx.doi.org/10.3389/fevo.2022.889357.
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Serious desertification problems were found in alpine grassland of the Qinghai-Tibet Plateau, China. The rehabilitation progress of degraded grassland is slow under natural conditions that have low rainfall and large evaporation. Organic agent-solidified soil is one of the most important measurements that limit desertification and grassland conservation-restoration. However, the characteristics of vegetation growth and development in solidified soil need to be studied in depth. This research is based on the modified carboxymethyl cellulose (MCMC) of independent development. Based on the sand soil taken from moving sandy land of Zoige, potted plants were tested in the environmental chamber at the laboratory. The physical, chemical, and biological characteristics of root soil were monitored for more than 7 months. As a result, the plant biomass in the experimental group increased, lodging rate decreased, drought tolerance and survival rate increased, and the number of plant roots and root surface area index, root cross-sectional area ratio, and root volume ratio increased compared with the matched group. It is shown that MCMC can effectively promote plant root development and improve plant drought tolerance and lodging resistance. We also found that, compared with the matched group, the values of the rhizosphere soil mass, root soil mass, and soil crust layer thickness of the experimental group were much higher, meaning that MCMC has strengthened the root soil-fixation ability and soil-crusting ability of plants. The soil nutrient indexes and bioactivity of the experimental group were higher than the matched group, indicating that MCMC has a positive influence on soil maturation. The quantitative description model of soil aging enhancement of MCMC material during root growth and development was established to explore the soil-fixation mechanism of MCMC plant root succession and provided an important scientific basis and technical support for the conservation and restoration of alpine grassland desertification grassland.