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991.
As the major source of air pollution, sulfur dioxide(SO_2) emissions have become the focus of global attention. However, existing studies rarely consider spatial effects when discussing the relationship between foreign direct investment(FDI) and SO_2 emissions. This study took the Yangtze River Delta as the research area and used the spatial panel data of 26 cities in this region for2004–2017. The study investigated the spatial agglomeration effects and dynamics at work in FDI and SO_2 emissions by using global and local measures of spatial autocorrelation. Then, based on regression analysis using a results of traditional ordinary least squares(OLS) model and a spatial econometric model, the spatial Durbin model(SDM) with spatial-time effects was adopted to quantify the impact of FDI on SO_2 emissions, so as to avoid the regression results bias caused by ignoring the spatial effects. The results revealed a significant spatial autocorrelation between FDI and SO_2 emissions, both of which displayed obvious path dependence characteristics in their geographical distribution. A series of agglomeration regions were observed on the spatial scale. The estimation results of the SDM showed that FDI inflow promoted SO_2 emissions, which supports the pollution haven hypothesis. The findings of this study are significant in the prevention and control of air pollution in the Yangtze River Delta. 相似文献
992.
Hydrologic flowpaths during snowmelt in forested headwater catchments under differing winter climatic and soil frost regimes 下载免费PDF全文
Changes in hydrologic flowpaths have important impacts on the timing, magnitude and hydrochemistry of run‐off during snowmelt in forested catchments, but how flowpaths are affected by variation in winter climate and the irregular presence of soil frost remains poorly understood. The depth and extent of soil frost may be expected to increase as snowpack decreases or develops later because of climate change. In this study, we used end‐member mixing analysis to determine daily contributions of snow, forest floor soil water and groundwater to stream run‐off during snowmelt under different soil frost regimes resulting from interannual and elevational variation at the Hubbard Brook Experimental Forest in New Hampshire, USA. We observed greater routing of run‐off through forest floor flowpaths during early snowmelt in 2011, when the snowpack was deep and soil frost was minimal, compared with the early snowmelt in 2012 under conditions of deep and extensive soil frost. The results indicate that widespread soil frost that penetrated the depth of the forest floor decreased the flow signal through the shallowest subsurface flowpaths, but did not reduce overall infiltration of melt waters, as the contribution from the snow‐precipitation end‐member was similar under both conditions. These results are consistent with development of granular soil frost which permits vertical infiltration of melt waters, but either reduces lateral flow in the forest floor or prevents the solute exchange that would produce the typical chemical signature of shallow subsurface flowpaths in streamwater. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
993.
994.
Temporal and spatial variability of extreme river flow quantiles in the Upper Vistula River basin,Poland 下载免费PDF全文
Temporal and spatial variability in extreme quantile anomalies of seasonal and annual maximum river flows was studied for 41 gauging stations at rivers in the Upper Vistula River basin, Poland. Using the quantile perturbation method, the temporal variability in anomalies was analysed. Interdecadal oscillating components were extracted from the series of anomalies using the Hilbert‐Huang transform method. Period length, part of variance of each component, and part of unexplained variance were assessed. Results show an oscillating pattern in the temporal occurrence of extreme flow quantiles with clusters of high values in the 1960–1970s and since the late 1990s and of low values in the 1980s and at the beginning of the 1990s. The anomalies show a high variability on the right bank of the Upper Vistula River basin during the summer season with the highest values in catchments located in the western and south‐western parts of the basin. River flow extreme quantiles were found to be associated with large‐scale climatic variables from the regions of the North Atlantic Ocean, Scandinavia, Eastern Europe, Asia, and, to a lesser extent, the Pacific Ocean. Similarities between temporal variability of river flows and climatic factors were revealed. Results of the study are important for flood frequency analysis because a long observation period is necessary to capture clusters of high and low river flows. 相似文献
995.
Morphological controls on the dynamics of carbonate landscapes under a mediterranean climate 下载免费PDF全文
Franck Thomas Vincent Godard Olivier Bellier Esmaeil Shabanian Vincent Ollivier Lucilla Benedetti Magali Rizza Nicolas Espurt Valéry Guillou Fabrice Hollender Stéphane Molliex ASTER Team 《地学学报》2017,29(3):173-182
The influence of the morphological setting on the denudation of carbonate landscapes and the respective contributions of mechanical and chemical weathering processes are still debated. We have addressed these questions by measuring 36Cl concentrations in 40 samples from the Luberon mountain, SE France, to constrain the denudation of various landscape elements. We observe a clear contrast between the local denudation rates from the flat summit surface, clustered around 30 mm/ka, and the basin‐average denudation rates across the flanks, ranging from 100 to 200 mm/ka. This difference highlights the transient evolution of the range, whose topography is still adjusting to previous uplift events. Such a pattern also suggests that carbonate dissolution is not the only driver of denudation in this setting, which appears to be significantly controlled by slope‐dependent processes. 相似文献
996.
Recent work by Braun, Duvall, and LaBonte has shown that sunspots absorb helioseismic waves. We propose that sunspot absorption causes a seismic deficit that should be imaged at the antipode of the sunspot. If these images are observable, it should be possible to produce seismic maps of magnetic regions on the far side of the Sun. This possibility opens a broad range of synoptic and diagnostic applications. Diagnostic applications would include lifetimes of higher-frequency modes, and possibly rotation of the solar interior and detection of subsurface magnetic structure. We outline elements of the theory of seismic imaging and consider some applications. We propose the extention of acoustic holography to solar interior diagnostics in the context of antipodal imaging.Now at the Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, U.S.A. 相似文献
997.
Charles J. Krieger 《Astrophysics and Space Science》1974,30(2):443-446
A method for the determination of distances of quasars and sites of absorbing media is presented. It is illustrated by application to 3C 191 and PKS 0237-23. The results are compared with those obtained from the traditional Hubble Law. 相似文献
998.
Harrison P. Jones Thomas L. Duvall Jr. John W. Harvey Charles T. Mahaffey Jan D. Schwitters Jorge E. Simmons 《Solar physics》1992,139(2):211-232
The NASA/NSO Spectromagnetograph is a new focal plane instrument for the National Solar Observatory/Kitt Peak Vacuum Telescope which features real-time digital analysis of long-slit spectra formed on a two-dimensional CCD detector. The instrument is placed at an exit port of a Littrow spectrograph and uses an existing modulator of circular polarization. The new instrument replaces the 512-channel Diode Array Magnetograph first used in 1973. Commercial video processing boards are used to digitize the spectral images at video rates and to separate, accumulate, and buffer the spectra in the two polarization states. An attached processor removes fixed-pattern bias and gain from the spectra in cadence with spatial scanning of the image across the entrance slit. The data control computer performs position and width analysis of the line profiles as they are acquired and records line-of-sight magnetic field, Doppler shift, and other computed parameters. The observer controls the instrument through windowed processes on a data control console using a keyboard and mouse. Early observations made with the spectromagnetograph are presented and plans for future development are discussed.The National Solar Observatory is a Division of the National Optical Astronomy Observatories which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. 相似文献
999.
1000.
Charles E. Worley 《Astrophysics and Space Science》1991,177(1-2):371-372
Any use of stars for astrometric purposes necessarily involves examination of their duplicity characteristics. The Washington Double Star Catalog (WDS) provides this information in a continuously updated and machine-readable format. This contribution describes the current data base and plans for its future extension. 相似文献