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This manuscript develops a logarithmic mean Divisia index I (LMDI) decomposition method based on energy and CO2 allocation Sankey diagrams to analyze the contributions of various influencing factors to the growth of energy-related CO2 emissions on a national level
. Compared with previous methods, we can further consider the influences of energy supply efficiency. Two key parameters, the primary energy quantity converted factor (KPEQ) and the primary carbon dioxide emission factor (KC), were introduced to calculate the equilibrium data for the whole process of energy unitization and related CO2 emissions. The data were used to map energy and CO2 allocation Sankey diagrams. Based on these parameters, we built an LMDI method with a higher technical resolution and applied it to decompose the growth of energy-related CO2 emissions in China from 2004 to 2014. The results indicate that GDP growth per capita is the main factor driving the growth of CO2 emissions while the reduction of energy intensity, the improvement of energy supply efficiency, and the introduction of non-fossil fuels in heat and electricity generation slowed the growth of CO2 emissions. © 2018 by the authors
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Gong, H.; Pan, Y.; Zheng, L.; Li, X.; Zhu, L.; Zhang, C.; Huang, Z.; Li, Z.; Wang, H.; Zhou, C.
The North China Plain (NCP) has been suffering from groundwater storage (GWS) depletion and land subsidence for a long period
. This paper collects data on GWS changes and land subsidence from in situ groundwater-level measurements, literature, and satellite observations to provide an overview of the evolution of the aquifer system during 1971–2015 with a focus on the sub-regional variations. It is found that the GWS showed a prolonged declining rate of −17.8 ± 0.1 mm/yr during 1971–2015, with a negative correlation to groundwater abstraction before year ~2000 and a positive correlation after ~2000. Statistical correlations between subsidence rate and the GWS anomaly (GWSA), groundwater abstraction, and annual precipitation show that the land subsidence in three sub-regions (Beijing, Tianjin, and Hebei) represents different temporal variations due to varying driver factors. Continuous drought caused intensive GWS depletion (−76.1 ± 6.5 mm/yr) and land subsidence in Beijing during 1999–2012. Negative correlations between total groundwater abstraction and land subsidence exhibited after the 1980s indicate that it may be questionable to infer subsidence from regional abstraction data. Instead, the GWSA generally provides a reliable correlation with subsidence. This study highlights the spatio-temporal variabilities of GWS depletion and land subsidence in the NCP under natural and anthropogenic impacts, and the importance of GWS changes for understanding land subsidence development
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Rock glaciers are widespread in the high mountains of western China
. However, they have not been systematically investigated for more than two decades. In this study, we propose a new method that combines SAR interferometry and optical images from Google Earth to map active rock glaciers (ARGs) in the Northern Tien Shan (NTS) in China. We compiled an inventory that includes 261 ARGs and quantitative information about their locations, geomorphic parameters, and down-slope velocities. Our inventory shows that most of the ARGs are moraine-derived (68 %) and facing north-east (56 %). The altitude distribution of ARGs in the western NTS is significantly different from those located in the eastern part. The down-slope velocities of the ARGs vary significantly in space, with a maximum of about 114 cm yr−1 and a mean of about 37 cm yr−1. Using the ARG locations as a proxy for the extent of alpine permafrost, our inventory suggests that the lowest altitudinal limit for the presence of permafrost in the Northern Tien Shan is about 2500–2800 m, a range determined by the lowest ARG in the entire inventory and by a statistics-based estimation. The successful application of the proposed method would facilitate an effective and robust effort to map rock glaciers over major mountain ranges and provide important datasets to improve mapping and modeling permafrost distribution in vast western China
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Qingbingtan Glacier No
. 72 in Mt. Tomor region is a small cirque-valley glacier with complex topography and debris-covered areas. Investigating its variation process will provide meaningful information for understanding the response of debris-covered glaciers existing broadly to climate change. The glacier accumulation area is characterized by receiving large amounts of precipitation and experiencing frequent snow/ice avalanches; temperature and flow regimes are analogous to a temperate or a monsoonal maritime glacier. Data from in-situ observations since 2008 and digitized earlier maps indicate the glacier has been in retreat and experienced thinning during the past 50 years. Between 1964 and 2008, its terminus retreat was 41 m a−1, area reduction was 0.034 km2 a−1, and its thickness decreased at an average rate of 0.6 m a−1 in the ablation area. With the melting enhancing, the proportion of the debris-covered area and thickness increased as well as inhibition of debris cover to melting. Thus, despite the persistent atmospheric warming during the last several decades, the strongest ablation and most significant terminus retreat and area reduction of the glacier occurred at the end of the last century and the beginning of this century rather than in most recent years. Based on a comprehensive analysis of climate change, glacier response delay, glacial topographic features and debris-cover influence, the glacier will continue to retreat in the upcoming decades, yet with a gradually decreasing speed. Then it will stabilize after its terminus retreats to an elevation of approximately 4000 m a.s.l
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Wu, G.; Li, Z.; Fu, C.; Zhang, X.; Zhang, R.; Zhang, R.; Zhou, T.; Li, J.; Li, J.; Zhou, D.; Wu, L.; Zhou, L.; He, B.; Huang, R.
Scientific issues relevant to interactions between aerosols and the Asian monsoon climate were discussed and evaluated at the 33rd 'Forum of Science and Technology Frontiers' sponsored by the Department of Earth Sciences at the Chinese Academy of Sciences
. Major results are summarized in this paper. The East Asian monsoon directly affects aerosol transport and provides a favorable background circulation for the occurrence and development of persistent fog-haze weather. Spatial features of aerosol transport and distribution are also influenced by the East Asian monsoon on seasonal, inter-annual, and decadal scales. High moisture levels in monsoon regions also affect aerosol optical and radiative properties. Observation analyses indicate that cloud physical properties and precipitation are significantly affected by aerosols in China with aerosols likely suppressing local light and moderate rainfall, and intensifying heavy rainfall in southeast coastal regions. However, the detailed mechanisms behind this pattern still need further exploration. The decadal variation in the East Asian monsoon strongly affects aerosol concentrations and their spatial patterns. The weakening monsoon circulation in recent decades has likely helped to increase regional aerosol concentrations. The substantial increase in Chinese air pollutants has likely decreased the temperature difference between land and sea, which favors intensification of the weakening monsoon circulation. Constructive suggestions regarding future studies on aerosols and monsoons were proposed in this forum and key uncertain issues were also discussed
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Zemp, M.; Frey, H.; Gärtner-Roer, I.; Nussbaumer, S. U.; Hoelzle, M.; Paul, F.; Haeberli, W.; Denzinger, F.; Ahlstrøm, A. P.; Anderson, B.; Bajracharya, S.; Baroni, C.; Braun, L. N.; Cáceres, B. E.; Casassa, G.; Cobos, G.; Dávila, L. R.; Delgado Granados, H.; Demuth, M. N.; Espizua, L.; Fischer, A.; Fujita, K.; Gadek, B.; Ghazanfar, A.; Hagen, J. O.; Holmlund, P.; Karimi, N.; Li, Z.; Pelto, M.; Pitte, P.; Popovnin, V. V.; Portocarrero, C. A.; Prinz, R.; Sangewar, C. V.; Severskiy, I.; Sigurðsson, O.; Soruco, A.; Usubaliev, R.; Vincent, C.
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In recent years attention has been given to assess the impacts of warming on the plant flowering phenology
. There is a growing realization that herbarium-based collections could offer a reliable and relatively time-saving baseline data source to identify these effects. This article examines the magnitude and trends of warming effects on the average flowering timing (AFT) of plants in Tibet Autonomous Region using analysis of herbarium specimens collected for 4 decades. Mixed model with randomized blocks was used to analyze a set of 41 species (total 909 specimens) which were collected during the period of 1961–2000. Results showed that an earlier AFT emerged within 40 years period in comparison to the recorded data of the year of 2000 (0.5 days per year), and that 7.5 days early flowering was contributed by mean summer (i.e., June–August) temperature. It is proposed that temporary shifts in flowering phenology responding to continuing temperature rise could quantify the extent to which climate affects plant species. Analysis of well recorded herbarium specimens could provide a reasonable indication on the impacts of rising temperature on plant phenology. The result of this study could also facilitate a bridge between the scientific knowledge and indigenous knowledge of Tibetan communities
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This paper addresses a snow-mapping algorithm for the Tibetan Plateau region using Moderate Resolution Imaging Spectroradiometer (MODIS) data
. Accounting for the effects of the atmosphere and terrain on the satellite observations at the top of the atmosphere (TOA), particularly in the rugged Tibetan Plateau region, the surface reflectance is retrieved from the TOA reflectance after atmospheric and topographic corrections. To reduce the effect of the misclassification of snow and cloud cover, a normalized difference cloud index (NDCI) model is proposed to discriminate snow/cloud pixels, separate from the MODIS cloud mask product MOD35. The MODIS land surface temperature (LST) product MOD11_L2 is also used to ensure better accuracy of the snow cover classification. Comparisons of the resulting snow cover with those estimated from high spatial-resolution Landsat ETM+ data and obtained from MODIS snow cover product MOD10_L2 for the Mount Everest region for different seasons in 2002, show that the MODIS snow cover product MOD10_L2 overestimates the snow cover with relative error ranging from 20.1% to 55.7%, whereas the proposed algorithm estimates the snow cover more accurately with relative error varying from 0.3% to 9.8%. Comparisons of the snow cover estimated with the proposed algorithm and those obtained from MOD10_L2 product with in situ measurements over the Hindu Kush-Himalayan (HKH) region for December 2003 and January 2004 (the snowy seasons) indicate that the proposed algorithm can map the snow cover more accurately with greater than 90% agreement
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Aerosols alter cloud density and the radiative balance of the atmosphere
. This leads to changes in cloud microphysics and atmospheric stability, which can either suppress or foster the development of clouds and precipitation. The net effect is largely unknown, but depends on meteorological conditions and aerosol properties. Here, we examine the long-term impact of aerosols on the vertical development of clouds and rainfall frequencies, using a 10-year dataset of aerosol, cloud and meteorological variables collected in the Southern Great Plains in the United States. We show that cloud-top height and thickness increase with aerosol concentration measured near the ground in mixed-phase clouds—which contain both liquid water and ice—that have a warm, low base. We attribute the effect, which is most significant in summer, to an aerosol-induced invigoration of upward winds. In contrast, we find no change in cloud-top height and precipitation with aerosol concentration in clouds with no ice or cool bases. We further show that precipitation frequency and rain rate are altered by aerosols. Rain increases with aerosol concentration in deep clouds that have a high liquid-water content, but declines in clouds that have a low liquid-water content. Simulations using a cloud-resolving model confirm these observations. Our findings provide unprecedented insights of the long-term net impacts of aerosols on clouds and precipitation
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This work aimed to refine the Moderate Resolution Imaging Spectroradiometer (MODIS) based snow cover algorithm for the Hindu Kush-Himalayan (HKH) region
. Taking into account the effect of the atmosphere and terrain on the satellite observations at the top of the atmosphere (TOA), particularly in heavily rugged Tibet plateau region, the surface reflectances were retrieved from the TOA reflectances after atmospheric and topographic corrections. To reduce the effects of the snow/cloud confusion, a normalized difference cloud index (NDCI) model was proposed to discriminate snow/cloud pixels, apart from use of the MODIS cloud mask product MOD35. Furthermore, MODIS land surface temperature (LST) product MOD11_L2 have been used to ensure better accuracy of the snow cover pixels. Comparisons of the resultant MODIS snow cover with those obtained respectively from high resolution Landsat ETM+ data and the MODIS snow cover product MOD10_L2 for the Mount Everest region at different seasons, showed overestimation of the MOD10_L2 snow cover with the differences of 50%, whereas the improved algorithm can estimate the snow cover for HKH region more precisely with absolute accuracy of 90%
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