With changing climatic conditions and snow cover regime, regional hydrological cycle for a snowy basin will change and further available surface water resources will be redistributed. Assessing snow meltwater effect o...With changing climatic conditions and snow cover regime, regional hydrological cycle for a snowy basin will change and further available surface water resources will be redistributed. Assessing snow meltwater effect on runoff is the key to water safety, under climate warming and fast social-economic developing status. In this study, stable isotopic technology was utilized to analyze the snow meltwater effect on regional hydrological processes, and to declare the response of snow hydrology to climate change and snow cover regime, together with longterm meteorological and hydrological observations, in the headwater of Irtysh River, Chinese Altai Mountains during 1961-2015. The average δ^(18) O values of rainfall, snowfall, meltwater, groundwater and river water for 2014–2015 hydrological year were-10.9‰,-22.3‰,-21.7‰,-15.7‰ and-16.0‰, respectively.The results from stable isotopes, snow melting observation and remote sensing indicated that the meltwater effect on hydrological processes in Kayiertesi River Basin mainly occurred during snowmelt supplying period from April to June. The contribution of meltwater to runoff reached 58.1% during this period, but rainfall, meltwater and groundwater supplied 49.1%, 36.9% and 14.0% of water resource to annual runoff, respectively. With rising air temperature and increasing snowfall in cold season, the snow water equivalent(SWE) had an increasing trend but the snow cover duration declined by about one month including 13-day delay of the first day and 17-day advancement of the end day during 1961–2016. Increase in SWE provided more available water resource. However, variations in snow cover timing had resulted in redistribution of surface water resource, represented by an increase of discharge percentage in April and May, and a decline in Juneand July. This trend of snow hydrology will render a deficit of water resource in June and July when the water resource demand is high for agricultural irrigation and industrial manufacture.展开更多
Black carbon(BC) deposited on snow and glacier surfaces can reduce albedo and lead to accelerated melt. An ice core recovered from Guoqu glacier on Mt. Geladaindong and analyzed using a Single Particle Soot Photometer...Black carbon(BC) deposited on snow and glacier surfaces can reduce albedo and lead to accelerated melt. An ice core recovered from Guoqu glacier on Mt. Geladaindong and analyzed using a Single Particle Soot Photometer(SP2) provides the ?rst long-term(1843-1982) record of BC from the central Tibetan Plateau. Post 1940 the record is characterized by an increased occurrence of years with above average BC, and the highest BC values of the record. The BC increase in recent decades is likely caused by a combination of increased emissions from regional BC sources, and a reduction in snow accumulation. Guoqu glacier has received no net ice accumulation since the 1980 s, and is a potential example of a glacier where an increase in the equilibrium line altitude is exposing buried high impurity layers. That BC concentrations in the uppermost layers of the Geladaindong ice core are not substantially higher relative to deeper in the ice core suggests that some of the BC that must have been deposited on Guoqu glacier via wet or dry deposition between 1983 and 2005 has been removed from the surface of the glacier, potentially via supraglacial or englacial meltwater.展开更多
Although dramatic warming is occurring in the Arctic,it is incomplete to provide an estimate to the Arctic Amplification(AA)based only on the surface air temperature(SAT)obtained at a few land stations.In this study,a...Although dramatic warming is occurring in the Arctic,it is incomplete to provide an estimate to the Arctic Amplification(AA)based only on the surface air temperature(SAT)obtained at a few land stations.In this study,a comprehensive evaluation has been made with sea surface temperature(SST)and SAT from the Arctic land and ocean.Additionally,the variations of sea surface parameters were analyzed for a better understanding of the updated Arctic changes in recent years.AA was underestimated by 4.3%when only considering the SAT.During 1982—2018,the Arctic and global SSTs increased dramatically after 2002 with a near-synchronous trend in 2011—2018.Sea ice extent exhibited negative anomalies in September and March after 2002,which were more significant in September.The warming was more remarkable in March than that in September,and the negative SST anomaly entirely disappeared in March in the last two years(2017—2018).However,sea ice thickness and snow depth in September increased with the positive anomaly in the southwestern Arctic Ocean.展开更多
Ice sheet serves as a crucial indicator for assessing climate change.Mass loss in recent remote sensing-based studies indicated that the Antarctic Peninsula has rapid rates of glacier retreat and speed up of surface v...Ice sheet serves as a crucial indicator for assessing climate change.Mass loss in recent remote sensing-based studies indicated that the Antarctic Peninsula has rapid rates of glacier retreat and speed up of surface velocity.However,observations of seasonal variability of ice speed are limited,and glacier-area changes require multi-temporal monitoring.This study investigated the changes in area and surface velocities of∼375 glaciers on the northern Antarctic Peninsula(NAP)utilizing satellite images acquired by the Sentinel 1&2 satellites during 2018-2022.The results indicate that the glacier area reduced by approximately 166.1±44.2 km^(2)(-0.2%±0.1%per year)during the study period,with an acceleration after 2020(-0.4%±0.3%per year),and the most dramatic reduction happened on the eastern NAP.The maximum annual ice speeds on the NAP generally exceeded 3500 m per year,while the ice speeds in 2021 were the highest(exceeded 4210 m per year).The ice speed variability in austral autumn was higher than in other seasons,meanwhile the summer ice speeds showed an increasing trend.The glacier G012158E47018N,McNeile Glacier,glacier G299637E64094S and Drygalski Glacier showed the most remarkable ice speed variations represented by high daily velocities and strong fluctuations on their termini.Our results demonstrated that the variations in glacier area and seasonal ice speed on the NAP were responsive to the ice-ocean-atmosphere processes.Therefore,seasonal velocity and area variations should be considered when conducting accurate mass balance calculations,model validations and change mechanism analyses under climate warming scenarios.展开更多
The continued warming of the Arctic atmosphere and ocean has led to a record retreat of sea ice in the last decades.This retreat has increased the probability of the opening of the Arctic Passages in the near future.T...The continued warming of the Arctic atmosphere and ocean has led to a record retreat of sea ice in the last decades.This retreat has increased the probability of the opening of the Arctic Passages in the near future.The Northwest Passage(NWP)is the most direct shipping route between the Atlantic and Pacific Oceans,producing notable economic benefits.Decadal variations of sea ice and its influencing factors from a high-resolution unstructured-grid finite-volume community ocean model were investigated along the NWP in 1988-2016,and the accessibility of the NWP was assessed under shared socioeconomic pathways(SSP245 and 585)and two vessel classes with the Arctic transportation acces-sibility model in 2021-2050.Sea ice thickness has decreased with increasing seawater temperature and salinity,especially within the Canadian Arctic Archipelago(CAA)in 1988-2016,which has facilitated the opening of the NWP.Complete ship navigation is projected to be possible for polar class 6 ships in August-December in 2021-2025,after when it may extends to July under SSP585 in 2026-2030,while open water ships will not be able to pass through the NWP until September in mid-21st century.The navigability of the NWP is mainly affected by the ice within the CAA.For the accessibility of the Parry Channel,the west part is worse than that of the eastern part,especially in the Viscount-Melville Sound.展开更多
Landsat satellite images were used to map and monitor the snow-covered areas of four glaciers with different aspects(Passu: 36.473°N, 74.766°E;Momhil: 36.394°N, 75.085°E; Trivor: 36.249°N,74.9...Landsat satellite images were used to map and monitor the snow-covered areas of four glaciers with different aspects(Passu: 36.473°N, 74.766°E;Momhil: 36.394°N, 75.085°E; Trivor: 36.249°N,74.968°E; and Kunyang: 36.083°N, 75.288°E) in the upper Indus basin, northern Pakistan, from 1990-2014. The snow-covered areas of the selected glaciers were identified and classified using supervised and rule-based image analysis techniques in three different seasons. Accuracy assessment of the classified images indicated that the supervised classification technique performed slightly better than the rule-based technique. Snow-covered areas on the selected glaciers were generally reduced during the study period but at different rates. Glaciers reached maximum areal snow coverage in winter and premonsoon seasons and minimum areal snow coverage in monsoon seasons, with the lowest snow-covered area occurring in August and September. The snowcovered area on Passu glacier decreased by 24.50%,3.15% and 11.25% in the pre-monsoon, monsoon and post-monsoon seasons, respectively. Similarly, the other three glaciers showed notable decreases in snow-covered area during the pre-and post-monsoon seasons; however, no clear changes were observed during monsoon seasons. During pre-monsoon seasons, the eastward-facing glacier lost comparatively more snow-covered area than the westward-facing glacier. The average seasonal glacier surface temperature calculated from the Landsat thermal band showed negative correlations of-0.67,-0.89,-0.75 and-0.77 with the average seasonal snowcovered areas of the Passu, Momhil, Trivor and Kunyang glaciers, respectively, during pre-monsoon seasons. Similarly, the air temperature collected from a nearby meteorological station showed an increasing trend, indicating that the snow-covered area reduction in the region was largely due to climate warming.展开更多
Recently, the light-absorbing organic carbon, i.e., brown carbon(Br C), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than t...Recently, the light-absorbing organic carbon, i.e., brown carbon(Br C), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than the purely scattering effect. Br C is ubiquitous in the troposphere. It could undergo long range transport within the atmospheric circulation. After the deposition on the surface of snow or ice in the cryospheric region, as the major light absorbing impurities with black carbon and dust, Br C could reduce the snow albedo and accelerate the glacier melting. In this context, this paper summarized the current knowledge of Br C(in aerosols and snow) in the cryospheric regions including the Arctic, Antarctic,and Alpines. Although some works have been conducted in those region, the current dataset on the optical properties of Br C like Absorption?ngstr€om Exponent(AAE) and Mass Absorption Efficiency(MAE) is still limited, which hampers stimulating an accurate evaluation of its climate effects. Especially in the Himalayas and Tibetan Plateau, where very limited information concerning Br C is available. Considering biomass burning as a dominant source of Br C, a large amount of emissions from biomass burning in South Asia could reach the Himalayas and Tibetan Plateau, where the climate effect of Br C merits more investigation in the future.展开更多
Solid precipitation is not only the main supply for glacier mass,but also exerts an important influence on surface albedo and intensifies glacier melting.However,precipitation type observation is very scarce in the hi...Solid precipitation is not only the main supply for glacier mass,but also exerts an important influence on surface albedo and intensifies glacier melting.However,precipitation type observation is very scarce in the high alpine glaciers,which limits the precise simulation of glacier mass balance.This study assessed three discrimination methods of precipitation types including Ding method,Dai method and Froidurot method based on surface albedo observation data on the Laohugou Glacier No.12(LHG Glacier)in western Qilian Mountains.The results showed that Ding method had a best applicability on the LHG Glacier,the other two need to calibrate parameters when they are used in the high elevation glacier region.Then we fitted the relationship between snowfall probability and fresh snow albedo,and put forward a revised formula to simulate fresh snow albedo based on Ding method,which is expected to reduce the uncertainty in glacier mass and energy balance model.Finally,we found a best air temperature threshold of 4℃for discriminating monthly precipitation types.In order to accurately simulate the glacier melt,it is necessary to obtain the threshold temperature appropriately in different glacier region with different elevation and humidity.展开更多
Background： Patellar dislocation is one of the most common knee injuries in the adolescent population. It is often combined with osteochondral fracture. The purpose of this study was to cornpare the outcomes between ...Background： Patellar dislocation is one of the most common knee injuries in the adolescent population. It is often combined with osteochondral fracture. The purpose of this study was to cornpare the outcomes between fixation and excision of osteochondral fractures not involving the bearing surface in adolescent patients with patellar dislocations. Methods： Patients who underwent surgery for osteochondral fracture following patellar dislocation in our institution from 2007 to 2014 were retrospectively evaluated. Visual analog scale （VAS） of pain and the International Knee Documentation Committee （IKI）C） form were used to assess knee pain and function at follow-up. Patient satisfaction was evaluated. Differences in the values of variables among groups were assessed using t-test if equal variance or Mann-Whitney U-test if not equal variance. The Pearson＇s Chi-square test was applied for dichotomous variables if expected frequency was 〉5 or Fisher＇s exact test was applied if not. A value of P 〈 0.05 was considered statistically significant. Results： Forty-three patients were included, with the average age of 14.1 ± 2.3 （range, 9.0-17.0） years. Nineteen underwent fixation of osteochondral fractures and 24 did not. The average follow-up time was 28 ± 10 months. There was no significant difference in age, gender, follow-up time, causes of injury, times of dislocation, and location of osteochondral fracture between fixation and excision groups. The fixation group had a significantly longer surgery time （82± 14 rain） and larger size of osteochondral fracture （2.30 ±0.70 cm2） than the excision group （43 ± 10 min, 1.88 ± 0.62 cm2, respectively, t = 10,77, P 〈 0.01 and t = 0.84, P 〈 0.05）. At the last follow-up, the average I KDC score in the fixation group （82.52 ± 8.71 ） was significantly lower than that in the excision group （89.51 ± 7.19, t 2.65, P 〈 0.01 ）. There was no significant difference in VAS of pain and patients＇ satisfaction. There were 7 （16%）展开更多
This paper presents an assessment of the Soil and Water Assessment Tool(SWAT) on a glaciated(Qugaqie) and a non-glaciated(Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau...This paper presents an assessment of the Soil and Water Assessment Tool(SWAT) on a glaciated(Qugaqie) and a non-glaciated(Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau, two subbasins having catchment areas of 59 km^2 and 388 km^2, respectively. The scores of examined evaluation indices(i.e., R^2, NSE, and PBIAS) established that the performance of the SWAT model was better on the monthly scale compared to the daily scale. The respective monthly values of R^2, NSE, and PBIAS were 0.94, 0.97, and 0.50 for the calibration period while 0.92, 0.88, and -8.80 for the validation period. Glacier melt contribution in the study domain was simulated by using the SWAT model in conjunction with the Degree Day Melt(DDM) approach. The conjunction of DDM with the SWAT Model ensued improved results during both calibration(R^2=0.96, NSE=0.95, and PBIAS=-13.49) and validation (R^2=0.97, NSE=0.96, and PBIAS=-2.87) periods on the monthly time scale. Average contribution(in percentage) of water balance components to the total streamflow of Niyaqu and Qugaqie subbasins was evaluated. We found that the major portion(99.45%) of the streamflow in the Niyaqu subbasin was generated by snowmelt or rainfall surface runoff(SURF_Q), followed by groundwater(GW_Q, 0.47%), and lateral(LAT_Q, 0.06%) flows. Conversely, in the Qugaqie subbasin, major contributor to the streamflow(79.63%) was glacier melt(GLC_Q), followed by SURF_Q(20.14%), GW_Q(0.13%), and LAT_Q(0.089%). The contribution of GLC_Q was the highest(86.79%) in July and lowest(69.95%) in September. This study concludes that the performance of the SWAT model in glaciated catchment is weak without considering glacier component in modeling; however, it performs reasonably well in non-glaciated catchment. Furthermore, the temperature index approach with elevation bands is viable in those catchments where streamflows are driven by snowmelt. Therefore, it is recommended to use the SWAT Model in conjunction with DDM or energy base model to simula展开更多
Tibetan Plateau(TP) lakes are important water resources,which are experiencing quick expansion in recent decades.Previous researches mainly focus on analyzing the relationship between terrestrial water storage(TWS) ch...Tibetan Plateau(TP) lakes are important water resources,which are experiencing quick expansion in recent decades.Previous researches mainly focus on analyzing the relationship between terrestrial water storage(TWS) change and lake water storage(LWS) change in the total inner TP,it is still lack of researches about the spatial difference and the characteristic of sub-region in the inner TP.In this study,we estimated the area change of 34 lakes by using Landsat images in the northeastern TP during 1976–2013,and LWS change by using the Shuttle Radar Topography Mission(SRTM).The results suggested that LWS had shrunk from 1976 to 1994,and then expanded quickly until 2013.LWS had a serious decrease by 13.6 Gt during 1976–1994,and then it increased quickly by 35.4 Gt during 1994–2013.We estimated TWS change,soil moisture change,and permafrost degradation based on the satellite data and related models during 2003–2013.The results indicated that their changing rates were 1.86 Gt/y,0.22 Gt/y,and –0.19 Gt/y,respectively.We also calculated the change of groundwater based on the mass balance with a decreasing trend of –0.054 Gt/y.The results suggested that the cause of TWS change was the increase of LWS.We analyzed the cause of lake change according to water balance,and found that the primary cause of lake expansion was the increasing precipitation(80.7%),followed by glacier meltwater(10.3%) and permafrost degradation(9%).The spatial difference between LWS change and TWS change should be studied further,which is important to understand the driving mechanism of water resources change.展开更多
Black carbon (BC) is formed from the incomplete combustion of fossil fuels (e.g. coal and diesel oil), biofuel and biomass (like wildfires). As the most strongly light-absorbing component of atmospheric aerosols, BC c...Black carbon (BC) is formed from the incomplete combustion of fossil fuels (e.g. coal and diesel oil), biofuel and biomass (like wildfires). As the most strongly light-absorbing component of atmospheric aerosols, BC could heat the atmosphere efficiently (i.e. the direct radiative forcing). Atmospheric BC also interacts with clouds to change cloud cover,lifetime, and brightness. Recently, the impact of BC on the cryosphere received increasing attention, because it could result in the significant glacier/snow cover melt through both the atmospheric warming and also the albedo reduction after its deposition on surface of snow/ice. Therefore, the importanceof BC as the major forcing in the climate system has been highlighted in the Fifth Assessment Report of IPCC.However, substantial uncertainty regarding its spatial-temporal distribution and climate effect still remains.展开更多
High-resolution ice core records covering long time spans enable reconstruction of the past climatic and environmental conditions allowing the investigation of the earth system's evolution. Preprocessing of ice co...High-resolution ice core records covering long time spans enable reconstruction of the past climatic and environmental conditions allowing the investigation of the earth system's evolution. Preprocessing of ice cores has direct impacts on the data quality control for further analysis since the conventional ice core processing is time-consuming, produces qualitative data, leads to ice mass loss, and leads to risks of potential secondary pollution. However, over the past several decades, preprocessing of ice cores has received less attention than the improvement of ice drilling, the analytical methodology of various indices, and the researches on the climatic and environmental significance of ice core records. Therefore, this papers reviews the development of the processing for ice cores including framework, design as well as materials, analyzes the technical advantages and disadvantages of the different systems. In the past, continuous flowanalysis(CFA) has been successfully applied to process the polar ice cores. However, it is not suitable for ice cores outside polar region because of high level of particles, the memory effect between samples, and the filtration before injection. Ice core processing is a subtle and professional operation due to the fragility of the nonmetallic materials and the random distribution of particles and air bubbles in ice cores, which aggravates uncertainty in the measurements. The future developments of CFA are discussed in preprocessing, memory effect, challenge for brittle ice, coupling with real-time analysis and optimization of CFA in the field. Furthermore, non-polluting cutters with many different configurations could be designed to cut and scrape in multiple directions and to separate inner and outer portions of the core. This system also needs to be coupled with streamlined operation of packaging, coding, and stacking that can be implemented at high resolution and rate, avoiding manual intervention. At the same time, information of the longitudinal sections could be scanned a展开更多
The cryosphere is the sphere around the Earth that has a certain thickness, existing at a temperature below 0 ℃, and it comprises components mainly including glaciers, ice sheets, snow cover, permafrost, lake and riv...The cryosphere is the sphere around the Earth that has a certain thickness, existing at a temperature below 0 ℃, and it comprises components mainly including glaciers, ice sheets, snow cover, permafrost, lake and river ice, sea ice, and ice shelves. It is regarded as one of spheres in the climate system, and well known for its sensitivity to climate change. Cryospheric science is an interdisciplinary subject related to all cryospheric components and is also linked to other earth sciences, including studies of the atmosphere, hydrosphere, biosphere, lithosphere, and anthroposphere (Qin et al., 2017).展开更多
Stream temperatures are sensitive to climate change and runoff regime variations. A comprehensive understanding on the effects of glacial melting on the stream temperatures are important in the Tibetan Plateau, of whi...Stream temperatures are sensitive to climate change and runoff regime variations. A comprehensive understanding on the effects of glacial melting on the stream temperatures are important in the Tibetan Plateau, of which contains the largest ice volume outside Polar Regions. This study documented the high-resolution stream temperature thermal regimes from glacier-fed and non-glacial rivers at four sites, versus a high-resolution glacier mass balance monitoring at Zhadang glacier, during summer melt seasons from 2007-2009 in the Nam Co basin of southern Tibetan Plateau. The results showed mean summer stream temperature and magnitude of daily thermal variation were lower at all sites when compared with alpine glacierized environments at lower latitudes. Mean stream temperatures for glacier-fed rivers(4.0℃ to 6.5℃)were minimum and least variable near the glacier terminus with increasing toward downstream(+0.13℃ km^(–1) to +0.28℃ km^(–1)). Meanwhile, stream temperature in 2008 was similar to that in 2007 and2009. For the non-glacial rivers, mean stream temperatures was about 9.0℃ with significantly warmer in summer months in 2009 and 2007 than that in 2008. These differences indicated that stream temperature was strongly influenced by discharge and precipitation. Particularly, the glacier mass balance played a large role on the stream temperature directly when the glacier melt contributed more than 50% of the glacial river runoff. Our results demonstrated the stream thermal variability from southern Tibetan rivers and provided new insight into the influence of glacier mass balance on stream thermal variability in high-altitude river system.展开更多
The profound impacts exerted by climate warming on the Tibetan Plateau have been documented extensively, but the biogeochemical responses remain poorly understood. This study was aimed at seasonal variations of total ...The profound impacts exerted by climate warming on the Tibetan Plateau have been documented extensively, but the biogeochemical responses remain poorly understood. This study was aimed at seasonal variations of total organic carbon(TOC) and total organic nitrogen(TON) in stream water at two gauging sections(TTH, ZMD) in the upper basin of Yangtze River(UBYA) and at fourgauging sections(HHY, JM, JG, TNH) in the upper basin of Yellow River(UBYE) in 2013. Results showed that concentrations of TON exhibit higher values in spring and winter and lower values in summer. TOC exhibits higher concentrations in spring or early summer and lower concentrations in autumn or winter. Seasonal variations of TOC and TON fluxes are dominated by water flux. In total, the UBYE and UBYA delivers 55,435 tons C of organic carbon and 9,872 tons N of organic nitrogen to downstream ecosystems in 2013. Although the combined flux ofTOC from UBYA and UBYE is far lower than those from large rivers, their combined yields is higher than, or comparable with, those from some large rivers(e.g. Nile, Orange, Columbia), implying that organic carbon from the Tibetan Plateau may exert a potentially influence on regional and/or global carbon cycles in future warming climate.展开更多
基金funded by the Chinese Academy of Sciences (KJZD-EW-G03-04, QYZDJSSW-DQC039)the National Science Foundation of China (NSFC 41630754, 41690144, 41421061)the Foundation of the State Key Laboratory of Cryospheric Sciences (SKLCS) at Northwest Institute of Eco-Environment and Resources (NIEER), CAS (SKLCS-OP-2017-10, SKLCS-ZZ2016)
文摘With changing climatic conditions and snow cover regime, regional hydrological cycle for a snowy basin will change and further available surface water resources will be redistributed. Assessing snow meltwater effect on runoff is the key to water safety, under climate warming and fast social-economic developing status. In this study, stable isotopic technology was utilized to analyze the snow meltwater effect on regional hydrological processes, and to declare the response of snow hydrology to climate change and snow cover regime, together with longterm meteorological and hydrological observations, in the headwater of Irtysh River, Chinese Altai Mountains during 1961-2015. The average δ^(18) O values of rainfall, snowfall, meltwater, groundwater and river water for 2014–2015 hydrological year were-10.9‰,-22.3‰,-21.7‰,-15.7‰ and-16.0‰, respectively.The results from stable isotopes, snow melting observation and remote sensing indicated that the meltwater effect on hydrological processes in Kayiertesi River Basin mainly occurred during snowmelt supplying period from April to June. The contribution of meltwater to runoff reached 58.1% during this period, but rainfall, meltwater and groundwater supplied 49.1%, 36.9% and 14.0% of water resource to annual runoff, respectively. With rising air temperature and increasing snowfall in cold season, the snow water equivalent(SWE) had an increasing trend but the snow cover duration declined by about one month including 13-day delay of the first day and 17-day advancement of the end day during 1961–2016. Increase in SWE provided more available water resource. However, variations in snow cover timing had resulted in redistribution of surface water resource, represented by an increase of discharge percentage in April and May, and a decline in Juneand July. This trend of snow hydrology will render a deficit of water resource in June and July when the water resource demand is high for agricultural irrigation and industrial manufacture.
基金funded by the National Science Foundation(OISE-0653933 and EAR-0957935)the National Natural Science Foundation of China(41121001,41225002)Geological Society of America Graduate Research Grant
文摘Black carbon(BC) deposited on snow and glacier surfaces can reduce albedo and lead to accelerated melt. An ice core recovered from Guoqu glacier on Mt. Geladaindong and analyzed using a Single Particle Soot Photometer(SP2) provides the ?rst long-term(1843-1982) record of BC from the central Tibetan Plateau. Post 1940 the record is characterized by an increased occurrence of years with above average BC, and the highest BC values of the record. The BC increase in recent decades is likely caused by a combination of increased emissions from regional BC sources, and a reduction in snow accumulation. Guoqu glacier has received no net ice accumulation since the 1980 s, and is a potential example of a glacier where an increase in the equilibrium line altitude is exposing buried high impurity layers. That BC concentrations in the uppermost layers of the Geladaindong ice core are not substantially higher relative to deeper in the ice core suggests that some of the BC that must have been deposited on Guoqu glacier via wet or dry deposition between 1983 and 2005 has been removed from the surface of the glacier, potentially via supraglacial or englacial meltwater.
基金the Frontier Science Key Project of CAS(QYZDY-SSW-DQC021,and QYZDJ-SSW-DQC039)the National Natural Science Foundation of China(41721091)+2 种基金Opening Fund of Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions,CAS(LPCC2018005)the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2020)Foundation for Excellent Youth Scholars of Northwest Institute of Eco-Environment and Resources,CAS(FEYS2019020).
文摘Although dramatic warming is occurring in the Arctic,it is incomplete to provide an estimate to the Arctic Amplification(AA)based only on the surface air temperature(SAT)obtained at a few land stations.In this study,a comprehensive evaluation has been made with sea surface temperature(SST)and SAT from the Arctic land and ocean.Additionally,the variations of sea surface parameters were analyzed for a better understanding of the updated Arctic changes in recent years.AA was underestimated by 4.3%when only considering the SAT.During 1982—2018,the Arctic and global SSTs increased dramatically after 2002 with a near-synchronous trend in 2011—2018.Sea ice extent exhibited negative anomalies in September and March after 2002,which were more significant in September.The warming was more remarkable in March than that in September,and the negative SST anomaly entirely disappeared in March in the last two years(2017—2018).However,sea ice thickness and snow depth in September increased with the positive anomaly in the southwestern Arctic Ocean.
基金This work was supported by the International Partnership Program of Chinese Academy of Sciences(121362KYSB20210024)We acknowledged the NASA MEaSUREs program in contribution to the Inter-mission Time Series of Land Ice Velocity and Elevation(ITS_LIVE)project(https://its-live.jpl.nasa.gov,last accesson:1 March 2022)and the compared data are available at https://doi.org/10.5281/zenodo.7521416.We are very grateful for the useful comments of reviewers and editors,which help us to improve the manuscript.
文摘Ice sheet serves as a crucial indicator for assessing climate change.Mass loss in recent remote sensing-based studies indicated that the Antarctic Peninsula has rapid rates of glacier retreat and speed up of surface velocity.However,observations of seasonal variability of ice speed are limited,and glacier-area changes require multi-temporal monitoring.This study investigated the changes in area and surface velocities of∼375 glaciers on the northern Antarctic Peninsula(NAP)utilizing satellite images acquired by the Sentinel 1&2 satellites during 2018-2022.The results indicate that the glacier area reduced by approximately 166.1±44.2 km^(2)(-0.2%±0.1%per year)during the study period,with an acceleration after 2020(-0.4%±0.3%per year),and the most dramatic reduction happened on the eastern NAP.The maximum annual ice speeds on the NAP generally exceeded 3500 m per year,while the ice speeds in 2021 were the highest(exceeded 4210 m per year).The ice speed variability in austral autumn was higher than in other seasons,meanwhile the summer ice speeds showed an increasing trend.The glacier G012158E47018N,McNeile Glacier,glacier G299637E64094S and Drygalski Glacier showed the most remarkable ice speed variations represented by high daily velocities and strong fluctuations on their termini.Our results demonstrated that the variations in glacier area and seasonal ice speed on the NAP were responsive to the ice-ocean-atmosphere processes.Therefore,seasonal velocity and area variations should be considered when conducting accurate mass balance calculations,model validations and change mechanism analyses under climate warming scenarios.
基金the National Natural Science Foundation of China(42005075,41721091)the Frontier Science Key Project of CAS(QYZDY-SSW-DQC021)+1 种基金the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2021)Foundation for Excellent Youth Scholars of Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences(FEYS2019020).
文摘The continued warming of the Arctic atmosphere and ocean has led to a record retreat of sea ice in the last decades.This retreat has increased the probability of the opening of the Arctic Passages in the near future.The Northwest Passage(NWP)is the most direct shipping route between the Atlantic and Pacific Oceans,producing notable economic benefits.Decadal variations of sea ice and its influencing factors from a high-resolution unstructured-grid finite-volume community ocean model were investigated along the NWP in 1988-2016,and the accessibility of the NWP was assessed under shared socioeconomic pathways(SSP245 and 585)and two vessel classes with the Arctic transportation acces-sibility model in 2021-2050.Sea ice thickness has decreased with increasing seawater temperature and salinity,especially within the Canadian Arctic Archipelago(CAA)in 1988-2016,which has facilitated the opening of the NWP.Complete ship navigation is projected to be possible for polar class 6 ships in August-December in 2021-2025,after when it may extends to July under SSP585 in 2026-2030,while open water ships will not be able to pass through the NWP until September in mid-21st century.The navigability of the NWP is mainly affected by the ice within the CAA.For the accessibility of the Parry Channel,the west part is worse than that of the eastern part,especially in the Viscount-Melville Sound.
基金funded by National Natural Science Foundation of China (41421061, 41630754)Chinese Academy of Sciences (KJZD-EW-G03-04)the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2017)
文摘Landsat satellite images were used to map and monitor the snow-covered areas of four glaciers with different aspects(Passu: 36.473°N, 74.766°E;Momhil: 36.394°N, 75.085°E; Trivor: 36.249°N,74.968°E; and Kunyang: 36.083°N, 75.288°E) in the upper Indus basin, northern Pakistan, from 1990-2014. The snow-covered areas of the selected glaciers were identified and classified using supervised and rule-based image analysis techniques in three different seasons. Accuracy assessment of the classified images indicated that the supervised classification technique performed slightly better than the rule-based technique. Snow-covered areas on the selected glaciers were generally reduced during the study period but at different rates. Glaciers reached maximum areal snow coverage in winter and premonsoon seasons and minimum areal snow coverage in monsoon seasons, with the lowest snow-covered area occurring in August and September. The snowcovered area on Passu glacier decreased by 24.50%,3.15% and 11.25% in the pre-monsoon, monsoon and post-monsoon seasons, respectively. Similarly, the other three glaciers showed notable decreases in snow-covered area during the pre-and post-monsoon seasons; however, no clear changes were observed during monsoon seasons. During pre-monsoon seasons, the eastward-facing glacier lost comparatively more snow-covered area than the westward-facing glacier. The average seasonal glacier surface temperature calculated from the Landsat thermal band showed negative correlations of-0.67,-0.89,-0.75 and-0.77 with the average seasonal snowcovered areas of the Passu, Momhil, Trivor and Kunyang glaciers, respectively, during pre-monsoon seasons. Similarly, the air temperature collected from a nearby meteorological station showed an increasing trend, indicating that the snow-covered area reduction in the region was largely due to climate warming.
基金supported by National Science Foundation of China (41522103, 41501082 and 41225002)Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues (XDA05100105)
文摘Recently, the light-absorbing organic carbon, i.e., brown carbon(Br C), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than the purely scattering effect. Br C is ubiquitous in the troposphere. It could undergo long range transport within the atmospheric circulation. After the deposition on the surface of snow or ice in the cryospheric region, as the major light absorbing impurities with black carbon and dust, Br C could reduce the snow albedo and accelerate the glacier melting. In this context, this paper summarized the current knowledge of Br C(in aerosols and snow) in the cryospheric regions including the Arctic, Antarctic,and Alpines. Although some works have been conducted in those region, the current dataset on the optical properties of Br C like Absorption?ngstr€om Exponent(AAE) and Mass Absorption Efficiency(MAE) is still limited, which hampers stimulating an accurate evaluation of its climate effects. Especially in the Himalayas and Tibetan Plateau, where very limited information concerning Br C is available. Considering biomass burning as a dominant source of Br C, a large amount of emissions from biomass burning in South Asia could reach the Himalayas and Tibetan Plateau, where the climate effect of Br C merits more investigation in the future.
基金supported by the National key research and development project(2022YFF0711704)the Science Fund for Creative Research Groups of Gansu Province(Grant No.23JRRA567)+2 种基金China Meteorological Administration Climate Change Special Program(CMA-CCSP:QBZ202308)Innovation and Development Project of China Meteorological Administration(CXFZ2022J039)the Gansu Provincial Science and Technology Program(22ZD6FA005)。
文摘Solid precipitation is not only the main supply for glacier mass,but also exerts an important influence on surface albedo and intensifies glacier melting.However,precipitation type observation is very scarce in the high alpine glaciers,which limits the precise simulation of glacier mass balance.This study assessed three discrimination methods of precipitation types including Ding method,Dai method and Froidurot method based on surface albedo observation data on the Laohugou Glacier No.12(LHG Glacier)in western Qilian Mountains.The results showed that Ding method had a best applicability on the LHG Glacier,the other two need to calibrate parameters when they are used in the high elevation glacier region.Then we fitted the relationship between snowfall probability and fresh snow albedo,and put forward a revised formula to simulate fresh snow albedo based on Ding method,which is expected to reduce the uncertainty in glacier mass and energy balance model.Finally,we found a best air temperature threshold of 4℃for discriminating monthly precipitation types.In order to accurately simulate the glacier melt,it is necessary to obtain the threshold temperature appropriately in different glacier region with different elevation and humidity.
基金This work was supported by grants from the General Financial Grant from the China Postdoctoral Science Foundation （No. 2016M602846）, the National Natural Science Foundation of China （No. 81702210）, and the Shaanxi Postdoctoral Science Foundation （No. 2017BSHQYXMZZ 16）.
文摘Background： Patellar dislocation is one of the most common knee injuries in the adolescent population. It is often combined with osteochondral fracture. The purpose of this study was to cornpare the outcomes between fixation and excision of osteochondral fractures not involving the bearing surface in adolescent patients with patellar dislocations. Methods： Patients who underwent surgery for osteochondral fracture following patellar dislocation in our institution from 2007 to 2014 were retrospectively evaluated. Visual analog scale （VAS） of pain and the International Knee Documentation Committee （IKI）C） form were used to assess knee pain and function at follow-up. Patient satisfaction was evaluated. Differences in the values of variables among groups were assessed using t-test if equal variance or Mann-Whitney U-test if not equal variance. The Pearson＇s Chi-square test was applied for dichotomous variables if expected frequency was 〉5 or Fisher＇s exact test was applied if not. A value of P 〈 0.05 was considered statistically significant. Results： Forty-three patients were included, with the average age of 14.1 ± 2.3 （range, 9.0-17.0） years. Nineteen underwent fixation of osteochondral fractures and 24 did not. The average follow-up time was 28 ± 10 months. There was no significant difference in age, gender, follow-up time, causes of injury, times of dislocation, and location of osteochondral fracture between fixation and excision groups. The fixation group had a significantly longer surgery time （82± 14 rain） and larger size of osteochondral fracture （2.30 ±0.70 cm2） than the excision group （43 ± 10 min, 1.88 ± 0.62 cm2, respectively, t = 10,77, P 〈 0.01 and t = 0.84, P 〈 0.05）. At the last follow-up, the average I KDC score in the fixation group （82.52 ± 8.71 ） was significantly lower than that in the excision group （89.51 ± 7.19, t 2.65, P 〈 0.01 ）. There was no significant difference in VAS of pain and patients＇ satisfaction. There were 7 （16%）
基金supported by National Natural Science Foundation of China (41671067 and 41630754)State Key Laboratory of Cryosphere Science (SKLCS-ZZ-2015)
文摘This paper presents an assessment of the Soil and Water Assessment Tool(SWAT) on a glaciated(Qugaqie) and a non-glaciated(Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau, two subbasins having catchment areas of 59 km^2 and 388 km^2, respectively. The scores of examined evaluation indices(i.e., R^2, NSE, and PBIAS) established that the performance of the SWAT model was better on the monthly scale compared to the daily scale. The respective monthly values of R^2, NSE, and PBIAS were 0.94, 0.97, and 0.50 for the calibration period while 0.92, 0.88, and -8.80 for the validation period. Glacier melt contribution in the study domain was simulated by using the SWAT model in conjunction with the Degree Day Melt(DDM) approach. The conjunction of DDM with the SWAT Model ensued improved results during both calibration(R^2=0.96, NSE=0.95, and PBIAS=-13.49) and validation (R^2=0.97, NSE=0.96, and PBIAS=-2.87) periods on the monthly time scale. Average contribution(in percentage) of water balance components to the total streamflow of Niyaqu and Qugaqie subbasins was evaluated. We found that the major portion(99.45%) of the streamflow in the Niyaqu subbasin was generated by snowmelt or rainfall surface runoff(SURF_Q), followed by groundwater(GW_Q, 0.47%), and lateral(LAT_Q, 0.06%) flows. Conversely, in the Qugaqie subbasin, major contributor to the streamflow(79.63%) was glacier melt(GLC_Q), followed by SURF_Q(20.14%), GW_Q(0.13%), and LAT_Q(0.089%). The contribution of GLC_Q was the highest(86.79%) in July and lowest(69.95%) in September. This study concludes that the performance of the SWAT model in glaciated catchment is weak without considering glacier component in modeling; however, it performs reasonably well in non-glaciated catchment. Furthermore, the temperature index approach with elevation bands is viable in those catchments where streamflows are driven by snowmelt. Therefore, it is recommended to use the SWAT Model in conjunction with DDM or energy base model to simula
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences,Pan-Third Pole Environment Study for a Green Silk Road (Pan-TPE) (XDA20040501)the second Tibetan Plateau Scientific Expedition and Research Program (STEP) (2019QZKK0605)the National Natural Science Foundation of China (41501073)。
文摘Tibetan Plateau(TP) lakes are important water resources,which are experiencing quick expansion in recent decades.Previous researches mainly focus on analyzing the relationship between terrestrial water storage(TWS) change and lake water storage(LWS) change in the total inner TP,it is still lack of researches about the spatial difference and the characteristic of sub-region in the inner TP.In this study,we estimated the area change of 34 lakes by using Landsat images in the northeastern TP during 1976–2013,and LWS change by using the Shuttle Radar Topography Mission(SRTM).The results suggested that LWS had shrunk from 1976 to 1994,and then expanded quickly until 2013.LWS had a serious decrease by 13.6 Gt during 1976–1994,and then it increased quickly by 35.4 Gt during 1994–2013.We estimated TWS change,soil moisture change,and permafrost degradation based on the satellite data and related models during 2003–2013.The results indicated that their changing rates were 1.86 Gt/y,0.22 Gt/y,and –0.19 Gt/y,respectively.We also calculated the change of groundwater based on the mass balance with a decreasing trend of –0.054 Gt/y.The results suggested that the cause of TWS change was the increase of LWS.We analyzed the cause of lake change according to water balance,and found that the primary cause of lake expansion was the increasing precipitation(80.7%),followed by glacier meltwater(10.3%) and permafrost degradation(9%).The spatial difference between LWS change and TWS change should be studied further,which is important to understand the driving mechanism of water resources change.
文摘Black carbon (BC) is formed from the incomplete combustion of fossil fuels (e.g. coal and diesel oil), biofuel and biomass (like wildfires). As the most strongly light-absorbing component of atmospheric aerosols, BC could heat the atmosphere efficiently (i.e. the direct radiative forcing). Atmospheric BC also interacts with clouds to change cloud cover,lifetime, and brightness. Recently, the impact of BC on the cryosphere received increasing attention, because it could result in the significant glacier/snow cover melt through both the atmospheric warming and also the albedo reduction after its deposition on surface of snow/ice. Therefore, the importanceof BC as the major forcing in the climate system has been highlighted in the Fifth Assessment Report of IPCC.However, substantial uncertainty regarding its spatial-temporal distribution and climate effect still remains.
基金supported by the National Natural Science Foundation of China(Grant No.41630754)the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2017)CAS Key Technology Talent Program and Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(2017490711)
文摘High-resolution ice core records covering long time spans enable reconstruction of the past climatic and environmental conditions allowing the investigation of the earth system's evolution. Preprocessing of ice cores has direct impacts on the data quality control for further analysis since the conventional ice core processing is time-consuming, produces qualitative data, leads to ice mass loss, and leads to risks of potential secondary pollution. However, over the past several decades, preprocessing of ice cores has received less attention than the improvement of ice drilling, the analytical methodology of various indices, and the researches on the climatic and environmental significance of ice core records. Therefore, this papers reviews the development of the processing for ice cores including framework, design as well as materials, analyzes the technical advantages and disadvantages of the different systems. In the past, continuous flowanalysis(CFA) has been successfully applied to process the polar ice cores. However, it is not suitable for ice cores outside polar region because of high level of particles, the memory effect between samples, and the filtration before injection. Ice core processing is a subtle and professional operation due to the fragility of the nonmetallic materials and the random distribution of particles and air bubbles in ice cores, which aggravates uncertainty in the measurements. The future developments of CFA are discussed in preprocessing, memory effect, challenge for brittle ice, coupling with real-time analysis and optimization of CFA in the field. Furthermore, non-polluting cutters with many different configurations could be designed to cut and scrape in multiple directions and to separate inner and outer portions of the core. This system also needs to be coupled with streamlined operation of packaging, coding, and stacking that can be implemented at high resolution and rate, avoiding manual intervention. At the same time, information of the longitudinal sections could be scanned a
文摘The cryosphere is the sphere around the Earth that has a certain thickness, existing at a temperature below 0 ℃, and it comprises components mainly including glaciers, ice sheets, snow cover, permafrost, lake and river ice, sea ice, and ice shelves. It is regarded as one of spheres in the climate system, and well known for its sensitivity to climate change. Cryospheric science is an interdisciplinary subject related to all cryospheric components and is also linked to other earth sciences, including studies of the atmosphere, hydrosphere, biosphere, lithosphere, and anthroposphere (Qin et al., 2017).
基金supported by the National Natural Science Foundation of China(41501063,41421061,913252001)Chinese Academy of Sciences(KJZD-EW-G03-04+1 种基金QYZDJ-SSWDQC039)the State Key Laboratory of Cryospheric Science(KJZD-ZZ-2017)
文摘Stream temperatures are sensitive to climate change and runoff regime variations. A comprehensive understanding on the effects of glacial melting on the stream temperatures are important in the Tibetan Plateau, of which contains the largest ice volume outside Polar Regions. This study documented the high-resolution stream temperature thermal regimes from glacier-fed and non-glacial rivers at four sites, versus a high-resolution glacier mass balance monitoring at Zhadang glacier, during summer melt seasons from 2007-2009 in the Nam Co basin of southern Tibetan Plateau. The results showed mean summer stream temperature and magnitude of daily thermal variation were lower at all sites when compared with alpine glacierized environments at lower latitudes. Mean stream temperatures for glacier-fed rivers(4.0℃ to 6.5℃)were minimum and least variable near the glacier terminus with increasing toward downstream(+0.13℃ km^(–1) to +0.28℃ km^(–1)). Meanwhile, stream temperature in 2008 was similar to that in 2007 and2009. For the non-glacial rivers, mean stream temperatures was about 9.0℃ with significantly warmer in summer months in 2009 and 2007 than that in 2008. These differences indicated that stream temperature was strongly influenced by discharge and precipitation. Particularly, the glacier mass balance played a large role on the stream temperature directly when the glacier melt contributed more than 50% of the glacial river runoff. Our results demonstrated the stream thermal variability from southern Tibetan rivers and provided new insight into the influence of glacier mass balance on stream thermal variability in high-altitude river system.
基金funded by the National Natural Science Foundation of China (91647102, 41671053, 41201060, 41271035, 41261017)Open Foundations of State Key Laboratory of Frozen Soil Engineering (SKLFSE201411)+5 种基金Open Foundation of the State Key Laboratory of Cryospheric Sciences (SKLCS-OP-2017-03)Open Foundations of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (2015490111)Fundamental Research Funds for the Central Universities (2014B16914)Special Fund of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (20145027312)Academy of Finland (Decision number 268170), Hundred Talents Program, Chinese Academy of Sciences Key Research Program (KZZD-EW-13)the Fundamental Research Funds for the Central Universities (NO. B14020167)
文摘The profound impacts exerted by climate warming on the Tibetan Plateau have been documented extensively, but the biogeochemical responses remain poorly understood. This study was aimed at seasonal variations of total organic carbon(TOC) and total organic nitrogen(TON) in stream water at two gauging sections(TTH, ZMD) in the upper basin of Yangtze River(UBYA) and at fourgauging sections(HHY, JM, JG, TNH) in the upper basin of Yellow River(UBYE) in 2013. Results showed that concentrations of TON exhibit higher values in spring and winter and lower values in summer. TOC exhibits higher concentrations in spring or early summer and lower concentrations in autumn or winter. Seasonal variations of TOC and TON fluxes are dominated by water flux. In total, the UBYE and UBYA delivers 55,435 tons C of organic carbon and 9,872 tons N of organic nitrogen to downstream ecosystems in 2013. Although the combined flux ofTOC from UBYA and UBYE is far lower than those from large rivers, their combined yields is higher than, or comparable with, those from some large rivers(e.g. Nile, Orange, Columbia), implying that organic carbon from the Tibetan Plateau may exert a potentially influence on regional and/or global carbon cycles in future warming climate.
