Schwannoma is a tumor derived from Schwann cells which usually arises in the upper extremities, trunk, head and neck, retroperitoneum, mediastinum, pelvis, and peritoneum. However, it can arise in the gastro-intestina...Schwannoma is a tumor derived from Schwann cells which usually arises in the upper extremities, trunk, head and neck, retroperitoneum, mediastinum, pelvis, and peritoneum. However, it can arise in the gastro-intestinal tract, including biliary tract. We present a 24-year-old male patient with obstructive jaundice, whose investigation with computed tomography abdomen showed focal wall thickening in the common hepatic duct, difficult to differentiate with hilar adenocarcinoma. He was diagnosed intraoperatively schwannoma of common bile duct and treated with local resection. The patient recovered well without signs of recurrence of the lesion after 12 mo. We also reviewed the common bile duct schwannoma related in the literature and evaluated the difficulty in pre and intraoperative differential diagnosis with adenocarcinoma hilar. Resection is the treatment of choice for such cases and the tumordid not recur in any of the resected cases.展开更多
By using daily air temperature and precipitation data, and the weather phenomena data of daily snowfall from 98 meteorological stations over the Qinghai-Tibetan Plateau (QTP), this paper performs an "at-risk" eval...By using daily air temperature and precipitation data, and the weather phenomena data of daily snowfall from 98 meteorological stations over the Qinghai-Tibetan Plateau (QTP), this paper performs an "at-risk" evaluation on snowfall and accumulated snow over the QTP under current climate situation and future climate warming condition. When rainfall, snowfall, or accumulated snow weather phenomena occur, critical values are determined based on dally air temperature and precipitation for current climate conditions. Air temperature of 0 ℃ is defined as the critical value of temperature for rainfall or snowfall, while 0 ℃ air temperature and 4.0 mm (autumn) or 3.0 mm (spring) snowfall amounts are defined as the critical values for accumulated snowfall. Analyses based on the above critical values disclose that under current climate condition, stations with "at-risk" accumulated snow account for 33% and 36% of all stations, and the "at-risk" snowfall stations reach 78% and 81% in autumn and spring, respectively. Spatially, most stations with "at-risk" accumulated snow are located on the southern and eastern edge of the QTP, and stations with "at-risk" snowfall are also apparent at the northern edge. If the air temperature increases by 2.5 ℃ in 2050, only the snowfall at a few "at-risk" snowfall stations will transform into rainfall, while most "at-risk" accumulated snow stations will face the problem that snowfall is hardly accumulated. Additionally, most stations will become "at-risk" accumulated snow stations, indicating that both the snow depth and the snow cover duration will decline in most areas of the QTP, including a delay of the start date and an advancing of the end date of snow cover.展开更多
The present reported study investigated the persistence of snow anomalies over the Tibetan Plateau(TP) from the preceding seasons to summer and the relationship between the previous snow cover anomaly and summer preci...The present reported study investigated the persistence of snow anomalies over the Tibetan Plateau(TP) from the preceding seasons to summer and the relationship between the previous snow cover anomaly and summer precipitation over East Asia. The results showed that, relative to other snow indices, such as the station observational snow depth(SOSD) index and the snow water equivalent(SWE) index, the snow cover area proportion(SCAP) index calculated from the SWE and the percentage of visible snow of the Equal-Area Scalable Earth Grids(EASE-grids) dataset has a higher persistence in interannual anomalies, particularly from May to summer. As such, the May SCAP index is significantly related to summer precipitation over the Meiyu-Baiu region. The persistence of the SCAP index can partly explain the season-delayed effect of snow cover over the TP on summer rainfall over the Meiyu-Baiu region besides the contribution of the soil moisture bridge. The preceding SST anomaly in the tropical Indian Ocean and ENSO can persist through the summer and affect the summer precipitation over the Meiyu-Baiu region. However, the May SCAP index is mostly independent of the simultaneous SSTs in the tropical Indian Ocean and the preceding ENSO and may affect the summer precipitation over the Meiyu-Baiu region independent of the effects of the SST anomalies. Therefore, the May SCAP over the TP could be regarded as an important supplementary factor in the forecasting of summer precipitation over the Meiyu-Baiu region.展开更多
On the basis of artificial neural network (ANN) model, this paper presents an algorithm for inversing snow depth with use of AMSR-E (Advanced Microwave Scanning Radiometer-Earth Observing System (EOS)) dataset, i.e., ...On the basis of artificial neural network (ANN) model, this paper presents an algorithm for inversing snow depth with use of AMSR-E (Advanced Microwave Scanning Radiometer-Earth Observing System (EOS)) dataset, i.e., brightness temperature at 18.7 and 36.5GHz in Qinghai-Tibet Plateau during the snow season of 2002-2003. In order to overcome the overfitting problem in ANN modeling, this methodology adopts a Bayesian regularization approach. The experiments are performed to compare the results obtained from the ANN-based algorithm with those obtained from other existing algorithms, i.e., Chang algorithm, spectral polarization difference (SPD) algorithm, and temperature gradient (TG) algorithm. The experimental results show that the presented algorithm has the highest accuracy in estimating snow depth. In addition, the effects of the noises in datasets on model fitting can be decreased due to adopting the Bayesian regularization approach.展开更多
Two ensemble experiments were conducted using a general atmospheric circulation model. These experiments were used to investigate the impacts of initial snow anomalies over the Tibetan Plateau(TP) on China precipitati...Two ensemble experiments were conducted using a general atmospheric circulation model. These experiments were used to investigate the impacts of initial snow anomalies over the Tibetan Plateau(TP) on China precipitation prediction. In one of the experiments, the initial snow conditions over the TP were climatological values; while in the other experiment, the initial snow anomalies were snow depth estimates derived from the passive microwave remote-sensing data. In the current study, the difference between these two experiments was assessed to evaluate the impact of initial snow anomalies over the TP on simulated precipitation. The results indicated that the model simulation for precipitation over eastern China had certain improvements while applying a more realistic initial snow anomaly, especially for spring precipitation over Northeast China and North China and for summer precipitation over North China and Southeast China. The results suggest that seasonal prediction could be enhanced by using more realistic initial snow conditions over TP, and microwave remote-sensing snow data could be used to initialize climate models and improve the simulation of eastern China precipitation during spring and summer. Further analyses showed that higher snow anomalies over TP cooled the surface, resulting in lower near- surface air temperature over the TP in spring and summer. The surface cooling over TP weakened the Asian summer monsoon and brought more precipitation in South China in spring and more precipitation to Southeast China during summer.展开更多
Based on the number of snow cover days (NSCDs) and homogenized surface air temperature data for the period 1951-2004, this study performs the quantitative analysis on the sensitivity of NSCDs to surface air temperat...Based on the number of snow cover days (NSCDs) and homogenized surface air temperature data for the period 1951-2004, this study performs the quantitative analysis on the sensitivity of NSCDs to surface air temperature over the Qinghai-Tibetan Plateau (QTP). Results show that both the extreme sensitivity and sensitivity under current climate are higher in the edge than in the central area of the QTP. There exists a strong negative correlation between station's elevation and critical temperature, at which the sensitivity reaches extremum. The negative correlation between the elevation and the extreme sensitivity is not as strong as the former one. Currently, the climatological temperatures in quite a few stations do not reach the critical stage. The sensitivity at these stations will become greater under the current background of climate warming, which means NSCDs will be more sensitive to surface air temperature.展开更多
Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods...Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods due to their short time scale. To address this issue of daily snowline and snow cover observations, a ground- based EOS 7D camera and four infrared digital hunting video cameras (LTL5210A) were installed around the Hulugou river basin (HRB) in the Qilian Mountains along northeastern margin of the Tibetan Plateau (38°15′54″N, 99°52′53″E) in September 2011. Pictures taken with the EOS 7D camera were georeferenced and the data from four LIL521oA cameras and snow depth sensors were used to assist snow cover estimation. The results showed that the time-lapse photography can be very useful and precise for monitoring snowline and snow cover in mountainous regions. The snowline and snow cover evolution at this basin can be precisely captured at daily scale. In HRB snow cover is mainly established after October, and the maximum snow cover appeared during February and March. The consistent rise of the snowline and decrease in snow cover appeared after middle part of March. This melt process is strongly associated with air temperature increase.展开更多
In this study we designed a novel,cost‐efficient and green method for the synthesis of copper nanoparticles(Cu NPs)supported on manganese dioxide(MnO2)NPs,using Centella asiatica L.leaf extract as a naturally‐source...In this study we designed a novel,cost‐efficient and green method for the synthesis of copper nanoparticles(Cu NPs)supported on manganese dioxide(MnO2)NPs,using Centella asiatica L.leaf extract as a naturally‐sourced reducing agent,without stabilizers or surfactants.This synthetic process is environmentally‐friendly and avoids the use of toxic reducing agents.Phenolic hydroxyl groups in the leaf extract are believed to reduce Cu2+in solution to generate Cu NPs that are subsequently stabilized on the MnO2NP surfaces.The resulting Cu/MnO2nanocomposite was fully characterized using X‐ray diffraction,transmission electron microscopy,field emission scanning electron microscopy,energy‐dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy.This material was found to function as a highly active,efficient and recyclable heterogeneous catalyst for the reduction of Congo red,rhodamine B and methylene blue as well as nitro compounds such as2,4‐dinitrophenylhydrazine and4‐nitrophenol in the presence of NaBH4in aqueous media at ambient temperature.The high stability of the Cu/MnO2nanocomposite also allows the catalyst to be separated and reused several times without any significant loss of activity.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.展开更多
A dipole pattern of summer precipitation over the mid-high latitudes of Asia, which is characterized by opposing summer precipitation variations between the Mongolian and Northeast China(MNC) region and the West Siber...A dipole pattern of summer precipitation over the mid-high latitudes of Asia, which is characterized by opposing summer precipitation variations between the Mongolian and Northeast China(MNC) region and the West Siberian Plain(WSP), is found to be clear and stable on both interdecadal and interannual scales during 1981–2011. Spring snow cover anomalies over a small region within the WSP and the Heilongjiang River(HR) region are closely related to the variation of this dipole mode during the subsequent summer, and they can therefore be considered as forecasting factors. Our statistical results imply a potential process explaining the relationship between the spring snow anomalies and the summer rainfall dipole. Corresponding to the snow anomalies, Rossby waves propagate along a path from the WSP region, via the Mongolian Plateau, to the Stanovoy Range during summer. At the same time, Rossby-wave energy divergences and convergences along this path maintain and reinforce an anomalous cyclone and anticyclone pairing over the Asian continent, which is significantly linked to opposite summer precipitation anomalies between the MNC and WSP regions. Numerical experiments are needed to further confirm the above conjecture and demonstrate the detailed physical mechanisms linking the spring snow cover anomalies and summer precipitation dipole.展开更多
The ice cap Ulugh Muztagh in the central Kunlun Shan at the northern fringe of the Tibetan Plateau is a very isolated region with arid cold conditions. No observational, meteorological or glaciological ground truth da...The ice cap Ulugh Muztagh in the central Kunlun Shan at the northern fringe of the Tibetan Plateau is a very isolated region with arid cold conditions. No observational, meteorological or glaciological ground truth data is available. Using the Moderate-resolution Imaging Spectroradiometer(MODIS) Level 1 radiance Swath Data(MOD02QKM) with a spatial resolution of 250 m, transient snow lines during the months of July to September in 2001 to 2014 are derived. Results are used to calibrate the physical based Coupled Snowpack and Ice surface energy and Mass balance model(COSIMA). The model runs on a representative detail region of Ulugh Muztagh(UM) on a digital elevation model with the same spatial resolution as the MODIS bands. In the absence of field observations, the model is driven solely by dynamically downscaled global analysis data from the High Asia Refined analysis(HAR). We compare remote sensing derived and modelled mean regional transient snow line altitudes in the course of consecutive summer seasons in 2008 to 2010. The resulting snow line altitude(SLA) and annual equilibrium line altitude(ELA) proxy of both methods coincide very well in their interannual variability in accordance with interannual variability of climatic conditions. Since SLAs of both methods do notconsistently agree on a daily basis a usage of remote sensing derived SLAs for model calibration in the absence of field observation data is only limitedly feasible for daily analysis. ELA approximation using the highest SLA at the end of ablation period may not be applied to UM because the negative winter mass balance(MB) is not reflected in the summer SLA. The study reveals moderate negative MB for UM throughout the modelling period. The mean regional MB of UM accounts for-523±410 mm w.e. a-1 in the modelling period. Hence UM seems not to belong to the area of the ‘Karakorum anomaly' comprising a region of positive mass balances in recent years which has its centre presumably in the Western Kunlun Shan.展开更多
The exchanges of NOx between snow and air have significant impact on the atmospheric components and photochemical processes in the overlying boundary layer. Such exchanges increase the oxidizing capacity of the atmosp...The exchanges of NOx between snow and air have significant impact on the atmospheric components and photochemical processes in the overlying boundary layer. Such exchanges increase the oxidizing capacity of the atmosphere and may have a crucial impact on the air signals that are retrieved from ice cores. In the recent years, sunlit snow and ice have been demonstrated to be important NOx sources in the polar atmospheric boundary layer. This paper makes a thorough review on the release of NOx from snow and ice, including field observations and experimental evidences, release mechanisms and influential parameters that affect such a release process, polar NOx concentrations and fluxes, and environmental impacts of the chemical processes of NOx in the polar atmospheric boundary layer. In the Tibetan Plateau, the released NOx observed recently in the sunlit snow/ice-cover is 1-order magnitude more than that in polar regions, but further scientific research is still needed to reveal its impact on the atmospheric oxidizing capacity.展开更多
Previous studies have revealed a significantly negative correlation between prior winter snow cover over the Tibetan Plateau (TPSC) and tropical cyclone genesis frequency (TCF) over the western North Pacific (WNP...Previous studies have revealed a significantly negative correlation between prior winter snow cover over the Tibetan Plateau (TPSC) and tropical cyclone genesis frequency (TCF) over the western North Pacific (WNP) in the following typhoon season. This study revisited this relationship based on long-term observational data. The results showed that the interannual correlation between TCF over the WNP and TPSC experienced a shift in the early 1990s. This correlation is significant during only 1993-2012 and is considerably weak during 1976-1992. The possible reasons causing the shift were examined further, and the results demonstrated that the central Pacific (CP) E1 Nifio-Southern Oscillation (ENSO) has played a vital role in intensifying the interannual relationship between TCF over the WNP and TPSC since the early 1990s. During 1993-2012, TPSC was negatively related to CP ENSO. When TPSC was higher than (lower than) normal, CP ENSO was often in its cold (warm) phase. Such a combination remarkably enhances the relationship of TPSC with the zonal land-sea thermal difference and thus with the summer monsoon over the WNE Additionally, it enhances the modulation of TPSC on the dynamical environments controlling TCF. As a result, the linkage between TPSC and TCF was significantly strengthened in this period. In sharp contrast, due to the weak relationship between TPSC and ENSO followed by the weak modulation of TPSC on the summer monsoon over the WNP and the dynamical environment during 1976-1992, the linkage between TPSC and TCF was weak during this time period. The results from additional dynamical diagnostic analyses further showed that during 1993-2012 CP ENSO modulated the barotropic energy conversion of zonal winds over the WNP, contributing to the intensified relationship between TPSC and TCF. These results will improve seasonal forecasting of tropical cyclone activity over the WNP.展开更多
The snow leopard(Panthera uncial,Figure 1A)is a kind of beautiful big cat that is believed to originate on the Tibetan Plateau seven million years ago(Tseng et al.,2013),and now inhabits alpine and subalpine zones...The snow leopard(Panthera uncial,Figure 1A)is a kind of beautiful big cat that is believed to originate on the Tibetan Plateau seven million years ago(Tseng et al.,2013),and now inhabits alpine and subalpine zones in the remote and rugged mountains on the Tibetan Plateau and its surrounding mountain ranges.展开更多
Resilience has become an important concept for the ski resorts of China,which have suffered heavy losses due to COVID-19.In order to help China’s ski resort service industry successfully adapt to the crisis and achie...Resilience has become an important concept for the ski resorts of China,which have suffered heavy losses due to COVID-19.In order to help China’s ski resort service industry successfully adapt to the crisis and achieve sustainable development,the goal of this paper is to develop the definition of resilience of the ski resort service industry through interviews based on the concept and general analysis framework of resilience.The ski resort resilience theory analysis framework is then constructed from the three basic elements(market,skiing,and stakeholders)and four system features(flexibility,adaptability,and collaborative learning ability).The results indicate several measures that can be taken to spread risk:enrich the product supply;eliminate risks and build a multi-agent networked industrial governance system;and establish a risk prevention and management mechanism based on a multi-organization alternative learning mechanism to overcome the difficulties encountered in the development of ski resorts.展开更多
文摘Schwannoma is a tumor derived from Schwann cells which usually arises in the upper extremities, trunk, head and neck, retroperitoneum, mediastinum, pelvis, and peritoneum. However, it can arise in the gastro-intestinal tract, including biliary tract. We present a 24-year-old male patient with obstructive jaundice, whose investigation with computed tomography abdomen showed focal wall thickening in the common hepatic duct, difficult to differentiate with hilar adenocarcinoma. He was diagnosed intraoperatively schwannoma of common bile duct and treated with local resection. The patient recovered well without signs of recurrence of the lesion after 12 mo. We also reviewed the common bile duct schwannoma related in the literature and evaluated the difficulty in pre and intraoperative differential diagnosis with adenocarcinoma hilar. Resection is the treatment of choice for such cases and the tumordid not recur in any of the resected cases.
基金supported by the opening fund from the State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences(SKLCS 08-07)the National Postdoctoral Scientific Foundation (20080440342)
文摘By using daily air temperature and precipitation data, and the weather phenomena data of daily snowfall from 98 meteorological stations over the Qinghai-Tibetan Plateau (QTP), this paper performs an "at-risk" evaluation on snowfall and accumulated snow over the QTP under current climate situation and future climate warming condition. When rainfall, snowfall, or accumulated snow weather phenomena occur, critical values are determined based on dally air temperature and precipitation for current climate conditions. Air temperature of 0 ℃ is defined as the critical value of temperature for rainfall or snowfall, while 0 ℃ air temperature and 4.0 mm (autumn) or 3.0 mm (spring) snowfall amounts are defined as the critical values for accumulated snowfall. Analyses based on the above critical values disclose that under current climate condition, stations with "at-risk" accumulated snow account for 33% and 36% of all stations, and the "at-risk" snowfall stations reach 78% and 81% in autumn and spring, respectively. Spatially, most stations with "at-risk" accumulated snow are located on the southern and eastern edge of the QTP, and stations with "at-risk" snowfall are also apparent at the northern edge. If the air temperature increases by 2.5 ℃ in 2050, only the snowfall at a few "at-risk" snowfall stations will transform into rainfall, while most "at-risk" accumulated snow stations will face the problem that snowfall is hardly accumulated. Additionally, most stations will become "at-risk" accumulated snow stations, indicating that both the snow depth and the snow cover duration will decline in most areas of the QTP, including a delay of the start date and an advancing of the end date of snow cover.
基金support of the National Science Foundation of China (Grant Nos. 41271434 and 41375090)the Hong Kong Research Grants Council (Grant No. CUHK403612)the Basic Research Fund of Chinese Academy of Meteorological Sciences (Grant No. 2013Z002)
文摘The present reported study investigated the persistence of snow anomalies over the Tibetan Plateau(TP) from the preceding seasons to summer and the relationship between the previous snow cover anomaly and summer precipitation over East Asia. The results showed that, relative to other snow indices, such as the station observational snow depth(SOSD) index and the snow water equivalent(SWE) index, the snow cover area proportion(SCAP) index calculated from the SWE and the percentage of visible snow of the Equal-Area Scalable Earth Grids(EASE-grids) dataset has a higher persistence in interannual anomalies, particularly from May to summer. As such, the May SCAP index is significantly related to summer precipitation over the Meiyu-Baiu region. The persistence of the SCAP index can partly explain the season-delayed effect of snow cover over the TP on summer rainfall over the Meiyu-Baiu region besides the contribution of the soil moisture bridge. The preceding SST anomaly in the tropical Indian Ocean and ENSO can persist through the summer and affect the summer precipitation over the Meiyu-Baiu region. However, the May SCAP index is mostly independent of the simultaneous SSTs in the tropical Indian Ocean and the preceding ENSO and may affect the summer precipitation over the Meiyu-Baiu region independent of the effects of the SST anomalies. Therefore, the May SCAP over the TP could be regarded as an important supplementary factor in the forecasting of summer precipitation over the Meiyu-Baiu region.
基金Under the auspices of Special Basic Research Fund for Central Public Scientific Research Institutes (No. 2007-03)
文摘On the basis of artificial neural network (ANN) model, this paper presents an algorithm for inversing snow depth with use of AMSR-E (Advanced Microwave Scanning Radiometer-Earth Observing System (EOS)) dataset, i.e., brightness temperature at 18.7 and 36.5GHz in Qinghai-Tibet Plateau during the snow season of 2002-2003. In order to overcome the overfitting problem in ANN modeling, this methodology adopts a Bayesian regularization approach. The experiments are performed to compare the results obtained from the ANN-based algorithm with those obtained from other existing algorithms, i.e., Chang algorithm, spectral polarization difference (SPD) algorithm, and temperature gradient (TG) algorithm. The experimental results show that the presented algorithm has the highest accuracy in estimating snow depth. In addition, the effects of the noises in datasets on model fitting can be decreased due to adopting the Bayesian regularization approach.
基金supported by the National Basic Research Program of China (Grant No. 2009CB421407)the Special Fund for Public Welfare (Meteorology) (Grant No. GYHY200906018)+1 种基金"Strategic Priority Research Program-Climate Change: Carbon Budget and Related Issues" of the Chinese Academy of Sciences (Grant No. XDA05110201)the National Key Technologies R&D Program of China (Grant No. 2007BAC29B03)
文摘Two ensemble experiments were conducted using a general atmospheric circulation model. These experiments were used to investigate the impacts of initial snow anomalies over the Tibetan Plateau(TP) on China precipitation prediction. In one of the experiments, the initial snow conditions over the TP were climatological values; while in the other experiment, the initial snow anomalies were snow depth estimates derived from the passive microwave remote-sensing data. In the current study, the difference between these two experiments was assessed to evaluate the impact of initial snow anomalies over the TP on simulated precipitation. The results indicated that the model simulation for precipitation over eastern China had certain improvements while applying a more realistic initial snow anomaly, especially for spring precipitation over Northeast China and North China and for summer precipitation over North China and Southeast China. The results suggest that seasonal prediction could be enhanced by using more realistic initial snow conditions over TP, and microwave remote-sensing snow data could be used to initialize climate models and improve the simulation of eastern China precipitation during spring and summer. Further analyses showed that higher snow anomalies over TP cooled the surface, resulting in lower near- surface air temperature over the TP in spring and summer. The surface cooling over TP weakened the Asian summer monsoon and brought more precipitation in South China in spring and more precipitation to Southeast China during summer.
基金supported by the National Postdoctoral Scientific Foundation(20080440342)the opening fund from the State Key Laboratory of Cryospheric Sciences,Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences(SKLCS 08-07)
文摘Based on the number of snow cover days (NSCDs) and homogenized surface air temperature data for the period 1951-2004, this study performs the quantitative analysis on the sensitivity of NSCDs to surface air temperature over the Qinghai-Tibetan Plateau (QTP). Results show that both the extreme sensitivity and sensitivity under current climate are higher in the edge than in the central area of the QTP. There exists a strong negative correlation between station's elevation and critical temperature, at which the sensitivity reaches extremum. The negative correlation between the elevation and the extreme sensitivity is not as strong as the former one. Currently, the climatological temperatures in quite a few stations do not reach the critical stage. The sensitivity at these stations will become greater under the current background of climate warming, which means NSCDs will be more sensitive to surface air temperature.
基金supported by the National Natural Sciences Foundation of China (Grant Nos. 41401078, 91025011, 41222001)National Basic Research Program of China (2013CBA01806)
文摘Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods due to their short time scale. To address this issue of daily snowline and snow cover observations, a ground- based EOS 7D camera and four infrared digital hunting video cameras (LTL5210A) were installed around the Hulugou river basin (HRB) in the Qilian Mountains along northeastern margin of the Tibetan Plateau (38°15′54″N, 99°52′53″E) in September 2011. Pictures taken with the EOS 7D camera were georeferenced and the data from four LIL521oA cameras and snow depth sensors were used to assist snow cover estimation. The results showed that the time-lapse photography can be very useful and precise for monitoring snowline and snow cover in mountainous regions. The snowline and snow cover evolution at this basin can be precisely captured at daily scale. In HRB snow cover is mainly established after October, and the maximum snow cover appeared during February and March. The consistent rise of the snowline and decrease in snow cover appeared after middle part of March. This melt process is strongly associated with air temperature increase.
文摘In this study we designed a novel,cost‐efficient and green method for the synthesis of copper nanoparticles(Cu NPs)supported on manganese dioxide(MnO2)NPs,using Centella asiatica L.leaf extract as a naturally‐sourced reducing agent,without stabilizers or surfactants.This synthetic process is environmentally‐friendly and avoids the use of toxic reducing agents.Phenolic hydroxyl groups in the leaf extract are believed to reduce Cu2+in solution to generate Cu NPs that are subsequently stabilized on the MnO2NP surfaces.The resulting Cu/MnO2nanocomposite was fully characterized using X‐ray diffraction,transmission electron microscopy,field emission scanning electron microscopy,energy‐dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy.This material was found to function as a highly active,efficient and recyclable heterogeneous catalyst for the reduction of Congo red,rhodamine B and methylene blue as well as nitro compounds such as2,4‐dinitrophenylhydrazine and4‐nitrophenol in the presence of NaBH4in aqueous media at ambient temperature.The high stability of the Cu/MnO2nanocomposite also allows the catalyst to be separated and reused several times without any significant loss of activity.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.
基金the joint support of the National Natural Science Foundation of China (Grant No. 41375090)the Basic Research Fund of the Chinese Academy of Meteorological Sciences (Grant No. 2013Z002)the International Cooperation and Exchange of the Ministry of Science and Technology of China (Grant No. 2009DFA21430)
文摘A dipole pattern of summer precipitation over the mid-high latitudes of Asia, which is characterized by opposing summer precipitation variations between the Mongolian and Northeast China(MNC) region and the West Siberian Plain(WSP), is found to be clear and stable on both interdecadal and interannual scales during 1981–2011. Spring snow cover anomalies over a small region within the WSP and the Heilongjiang River(HR) region are closely related to the variation of this dipole mode during the subsequent summer, and they can therefore be considered as forecasting factors. Our statistical results imply a potential process explaining the relationship between the spring snow anomalies and the summer rainfall dipole. Corresponding to the snow anomalies, Rossby waves propagate along a path from the WSP region, via the Mongolian Plateau, to the Stanovoy Range during summer. At the same time, Rossby-wave energy divergences and convergences along this path maintain and reinforce an anomalous cyclone and anticyclone pairing over the Asian continent, which is significantly linked to opposite summer precipitation anomalies between the MNC and WSP regions. Numerical experiments are needed to further confirm the above conjecture and demonstrate the detailed physical mechanisms linking the spring snow cover anomalies and summer precipitation dipole.
基金supported by the German Research Foundation(DFG)Priority Programme 1372,‘Tibetan Plateau:Formation Climate Ecosystems’through the DynRG-TiP(‘Dynamic Response of Glaciers on the Tibetan Plateau to Climate Change’)project under codes SCHN 680/3-3 and SCHE 750/4-3the German Federal Ministry of Education and Research(BMBF)Central Asia Monsoon Dynamics and GeoEcosystems(CAME)program,through the WET project(‘Variability and Trends in Water Balance Components of Benchmark Drainage Basins on the Tibetan Plateau’)under code 03G0804A
文摘The ice cap Ulugh Muztagh in the central Kunlun Shan at the northern fringe of the Tibetan Plateau is a very isolated region with arid cold conditions. No observational, meteorological or glaciological ground truth data is available. Using the Moderate-resolution Imaging Spectroradiometer(MODIS) Level 1 radiance Swath Data(MOD02QKM) with a spatial resolution of 250 m, transient snow lines during the months of July to September in 2001 to 2014 are derived. Results are used to calibrate the physical based Coupled Snowpack and Ice surface energy and Mass balance model(COSIMA). The model runs on a representative detail region of Ulugh Muztagh(UM) on a digital elevation model with the same spatial resolution as the MODIS bands. In the absence of field observations, the model is driven solely by dynamically downscaled global analysis data from the High Asia Refined analysis(HAR). We compare remote sensing derived and modelled mean regional transient snow line altitudes in the course of consecutive summer seasons in 2008 to 2010. The resulting snow line altitude(SLA) and annual equilibrium line altitude(ELA) proxy of both methods coincide very well in their interannual variability in accordance with interannual variability of climatic conditions. Since SLAs of both methods do notconsistently agree on a daily basis a usage of remote sensing derived SLAs for model calibration in the absence of field observation data is only limitedly feasible for daily analysis. ELA approximation using the highest SLA at the end of ablation period may not be applied to UM because the negative winter mass balance(MB) is not reflected in the summer SLA. The study reveals moderate negative MB for UM throughout the modelling period. The mean regional MB of UM accounts for-523±410 mm w.e. a-1 in the modelling period. Hence UM seems not to belong to the area of the ‘Karakorum anomaly' comprising a region of positive mass balances in recent years which has its centre presumably in the Western Kunlun Shan.
基金supported by the Fund of Polar Scientific Research(No.20080216) of State Ocean Administration, Chinaby Chinese Natural Science Foundation(No. 20407001,No.40701170)
文摘The exchanges of NOx between snow and air have significant impact on the atmospheric components and photochemical processes in the overlying boundary layer. Such exchanges increase the oxidizing capacity of the atmosphere and may have a crucial impact on the air signals that are retrieved from ice cores. In the recent years, sunlit snow and ice have been demonstrated to be important NOx sources in the polar atmospheric boundary layer. This paper makes a thorough review on the release of NOx from snow and ice, including field observations and experimental evidences, release mechanisms and influential parameters that affect such a release process, polar NOx concentrations and fluxes, and environmental impacts of the chemical processes of NOx in the polar atmospheric boundary layer. In the Tibetan Plateau, the released NOx observed recently in the sunlit snow/ice-cover is 1-order magnitude more than that in polar regions, but further scientific research is still needed to reveal its impact on the atmospheric oxidizing capacity.
基金supported by the China Meteorological Administration Special Public Welfare Research Fund(Grant No.GYHY201406001)National Key Basic Research Program of China(Grant No.2012CB956003)+1 种基金the National Natural Science Foundation of China(Grant No.41375093)supported in part by the Youth Elite Project of the CMA
文摘Previous studies have revealed a significantly negative correlation between prior winter snow cover over the Tibetan Plateau (TPSC) and tropical cyclone genesis frequency (TCF) over the western North Pacific (WNP) in the following typhoon season. This study revisited this relationship based on long-term observational data. The results showed that the interannual correlation between TCF over the WNP and TPSC experienced a shift in the early 1990s. This correlation is significant during only 1993-2012 and is considerably weak during 1976-1992. The possible reasons causing the shift were examined further, and the results demonstrated that the central Pacific (CP) E1 Nifio-Southern Oscillation (ENSO) has played a vital role in intensifying the interannual relationship between TCF over the WNP and TPSC since the early 1990s. During 1993-2012, TPSC was negatively related to CP ENSO. When TPSC was higher than (lower than) normal, CP ENSO was often in its cold (warm) phase. Such a combination remarkably enhances the relationship of TPSC with the zonal land-sea thermal difference and thus with the summer monsoon over the WNE Additionally, it enhances the modulation of TPSC on the dynamical environments controlling TCF. As a result, the linkage between TPSC and TCF was significantly strengthened in this period. In sharp contrast, due to the weak relationship between TPSC and ENSO followed by the weak modulation of TPSC on the summer monsoon over the WNP and the dynamical environment during 1976-1992, the linkage between TPSC and TCF was weak during this time period. The results from additional dynamical diagnostic analyses further showed that during 1993-2012 CP ENSO modulated the barotropic energy conversion of zonal winds over the WNP, contributing to the intensified relationship between TPSC and TCF. These results will improve seasonal forecasting of tropical cyclone activity over the WNP.
文摘The snow leopard(Panthera uncial,Figure 1A)is a kind of beautiful big cat that is believed to originate on the Tibetan Plateau seven million years ago(Tseng et al.,2013),and now inhabits alpine and subalpine zones in the remote and rugged mountains on the Tibetan Plateau and its surrounding mountain ranges.
基金The Youth Project of Humanities and Social Sciences of the Ministry of Education(20YJC890032).
文摘Resilience has become an important concept for the ski resorts of China,which have suffered heavy losses due to COVID-19.In order to help China’s ski resort service industry successfully adapt to the crisis and achieve sustainable development,the goal of this paper is to develop the definition of resilience of the ski resort service industry through interviews based on the concept and general analysis framework of resilience.The ski resort resilience theory analysis framework is then constructed from the three basic elements(market,skiing,and stakeholders)and four system features(flexibility,adaptability,and collaborative learning ability).The results indicate several measures that can be taken to spread risk:enrich the product supply;eliminate risks and build a multi-agent networked industrial governance system;and establish a risk prevention and management mechanism based on a multi-organization alternative learning mechanism to overcome the difficulties encountered in the development of ski resorts.