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101.
The complex politics of climate change cannot be properly understood without reference to deeper geopolitical trends in the wider international system. Chief among these is the growing resurgence of ‘great-power politics’ between China and the US, along with failures of socialization and enmeshment into global governance structures in relation to these two powers. Traditional theoretical frameworks have failed to adequately account for these developments. Nonetheless, this current great-power contestation is at the core of an order transition that has prevented the large-scale institutional redesign required to remove deadlocks in existing global governance structures, including climate governance. Examples from the 2009 Copenhagen Climate Change Conference provide ample evidence for these claims. The slow progress of the climate change negotiations are due not just to the politics of the issue itself, but to the absence of a new political bargain on material power structures, normative beliefs, and the management of the order amongst the great powers. Without such a grand political bargain, which could be promoted through a forum of major economies whose wide-ranging remit would go beyond single issues, the climate change regime is only ever likely to progress in a piecemeal fashion. Policy relevance Despite the achievements of the 2012 Doha Climate Change Conference, the climate negotiations are not on course to limit warming to 2 °C, and thereby avoid ‘dangerous’ climate change. Several factors have been invoked to account for such slow progress: notably, the nature of the climate change problem itself, the institutional structure of the climate regime, and lack of political will among key players. An alternative explanation is proposed such that the failure to seriously address climate change – as well as other global problems – reflects a resurgent meta-struggle between the ‘great powers’ of China and the US over the nature of the global order. Without such a broader understanding of the deeper dynamics underlying the stalemates of the climate change negotiations, there is little chance of turning those negotiations around. 相似文献
102.
103.
The study analyses the numbers of days with strong winds in Krakow during the period 2000?C2007 using anemometric records and fire department data. Patterns are identified in the seasonal and annual variation of strong winds. Particular attention is devoted to extreme events. Based on measurements, the study finds that strong winds mostly occurred in winter. Fire department call-out data show that repair of damage caused by strong winds and gusts of wind was needed equally as frequently in summertime. Strong winds accompanying summer storms are often of a local nature and are not always recorded by weather stations. Wind damage was mapped using requests for fire department assistance. 相似文献
104.
Wu Y Ajo-Franklin JB Spycher N Hubbard SS Zhang G Williams KH Taylor J Fujita Y Smith R 《Geochemical transactions》2011,12(1):7-20
Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH4+ production during urea hydrolysis were incorporated in the model and captured critical changes in the major metal species. The electrical phase increases were potentially due to ion exchange processes that modified charge structure at mineral/water interfaces. Our study revealed the potential of geophysical monitoring for geochemical changes during urea hydrolysis and the advantages of combining multiple approaches to understand complex biogeochemical processes in the subsurface. 相似文献
105.
We measured seasonal variations in microzooplankton grazing in Long Island Sound (LIS) and San Francisco Bay (SFB). There
was consistent evidence of nutrient limitation in LIS, but not SFB. We found higher chlorophyll a concentrations in LIS compared with SFB. In spite of differences in phytoplankton, there were no differences in microzooplankton
abundance (summer: LIS, 12.4 ± 1.8 × 103 indiv. L−1; SFB, 14.1 ± 3.0 × 103 indiv. L−1), biomass (summer: LIS, 30.4 ± 5.0 μg C L−1; SFB, 26.3 ± 5.9 μg C L−1), or grazing rates (summer: LIS, 0.66 ± 0.19 day−1; SFB, 0.65 ± 0.18 day−1) between the two estuaries. In common with many other investigators, we found many instances of saturated as well as insignificant
grazing. We suggest that saturation in some cases may result from high particle loads in turbid estuarine systems and that
insignificant grazing may result from extreme saturation of the grazing response due to the need to process non-food particles. 相似文献
106.
Pulsar B1929+10 is remarkable on a number of grounds. Its narrow primary components exhibit virtually complete and highly
stable linear polarisation, which can be detected over most of its rotation cycle. Various workers have been lured by the
unprecedented range over which its linear polarisation angle can be determined, and more attempts have been made to model
its emission geometry than perhaps for any other pulsar. Paradoxically, there is compelling evidence to interpret the pulsar’s
emission geometryboth in terms of an aligned configuration whereby its observed radiation comes from a single magnetic-polar emission regionand in terms of a nearly orthogonal configuration in which we receive emission from regions near each of its two poles. Pulsar
1929+10 thus provides a fascinating context in which to probe the conflict between these lines of interpretation in an effort
to deepen our understanding of pulsar radio emission.
Least-squares fits to the polarisation-angle traverse fit poorly near the main pulse and interpulse and have an inflection
point far from the centre of the main pulse. This and a number of other circumstances suggest that the position-angle traverse
is an unreliable indicator of the geometry in this pulsar, possibly in part because its low level ‘pedestal’ emission makes
it impossible to properly calibrate a Polarimeter which correlates orthogonal circular polarisations.
Taking the interpulse and main-pulse comp. II widths as indicators of the magnetic latitude, it appears that pulsar 1929+10
has anα value near 90‡ and thus has a two-pole interpulse geometry. This line of interpretation leads to interesting and consistent
results regarding the geometry of the conal components. Features corresponding to both an inner and outer cone are identified.
In addition, it appears that pulsar 1929+10–and a few other stars–have what we are forced to identify as a ‘furtherin’ cone,
with a conal emission radius of about2.3‡/P
1/2
Secondarily, 1929+10’s nearly complete linear polarisation provides an ideal opportunity to study how mechanisms of depolarisation
function on a pulse-to-pulse basis. Secondary-polarisation-mode emission appears in significant proportion only in some limited
ranges of longitude, and the subsequent depolarization is studied using different mode-separation techniques. The characteristics
of the two polarisation modes are particularly interesting, both because the primary mode usually dominates the secondary
so completely and because the structure seen in the secondary mode appears to bear importantly on the question of the pulsar’s
basic emission geometry. New secondary-mode features are detected in the average profile of this pulsar which appear independent
of the main-pulse component structure and which apparently constitute displaced modal emission.
Individual pulses during which the secondary-mode dominates the primary one are found to be considerably more intense than
the others and largely depolarised. Monte-Carlo modeling of the mode mixing in this region, near the boundary of comps. II
and III, indicates that the incoherent interference of two fully and orthogonally polarised modes can adequately account for
the observed depolarisation. The amplitude distributions of the two polarisation modes are both quite steady: the primary
polarisation mode is well fitted by a χ2 distribution with about nine degrees of freedom; whereas the secondary mode requires a more intense distribution which is
constant, but sporadic. 相似文献
107.
Andrew Bunker Joanna Smith Hyron Spinrad Daniel Stern Stephen Warren 《Astrophysics and Space Science》2003,284(2):357-360
We have discovered extended Lyman-α emission around a z=4.5 QSO in a deep long-slit spectrum with Keck/LRIS at moderate spectral resolution (R≈ 1000). The line emission extends 5 arcsec beyond the continuum of the QSO and is spatially asymmetric. This extended line
emission has a spectral extent of 1000km/s, much narrower in velocity spread than the broad Lyman-α from the QSO itself and
slightly offset in redshift. No evidence of continuum is seen for the extended emission line region, suggesting that this
recombination line is powered by reprocessed QSO Lyman continuum flux rather than by local star formation. This phenomenon
is rare in QSOs which are not radio loud, and this is the first time it has been observed at z>4. It seems likely that the QSO is illuminating the surrounding cold gas of the host galaxy, with the ionizing photons producing
Lyman-α fluorescence. As suggested by Haiman and Rees (2001), this `fuzz' around a distant quasar may place strong constraints
on galaxy formation and the extended distribution of cold, neutral gas.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
108.
Alexander Port Klaus-Werner Gurgel Joanna Staneva Johannes Schulz-Stellenfleth Emil V. Stanev 《Ocean Dynamics》2011,61(10):1567-1585
Tidal and wind-driven surface currents in the German Bight between shallow mudflats of the North Frisian islands and the island
of Helgoland are studied using coastal high-frequency radar (HFR) observations and hindcasts from a primitive equation numerical
model. The setup of the observational system is described, and estimates of expected measurement errors are given. A quantitative
comparison of numerical model results and observations is performed. The dominant tidal components are extracted from the
two data sources using tidal harmonic analysis and the corresponding tidal ellipses are defined. Results show that the spatial
patterns of different tidal ellipse parameters are consistent in the two data sets. Model sensitivity studies with constant
and variable salinity and temperature distributions are used to study density-related mechanisms of circulation. Furthermore,
the role of the surface wind field in driving the German Bight circulation is investigated using the complex correlation between
wind and surface current vectors. The observed change of the respective correlation patterns from the coastal to open ocean
is shown to be due to a combination of density effects, the coastline and topography. The overall conclusion is that HFR observations
resolve the small-scale and rapidly evolving characteristics of coastal currents well in the studied area and could present
an important component for regional operational oceanography when combined with numerical modelling. Some unresolved issues
associated with the complex circulation and large instability of circulation in front of the Elbe River Estuary justify further
considerations of this area using dedicated surveys and modelling efforts. 相似文献
109.
Wojciech W. Grabowski Joanna Slawinska Hanna Pawlowska Andrzej A. Wyszogrodzki 《Acta Geophysica》2011,59(6):1184-1204
This paper presents application of the EULAG model combined with a sophisticated double-moment warm-rain microphysics scheme to the model intercomparison case based on RICO (Rain in Cumulus over Ocean) field observations. As the simulations progress, the cloud field gradually deepens and a relatively sharp temperature and moisture inversions develop in the lower troposphere. Two contrasting aerosol environments are considered, referred to as pristine and polluted, together with two contrasting subgridscale mixing scenarios, the homogeneous and the extremely inhomogeneous mixing. Pristine and polluted environments feature mean cloud droplet concentrations around 40 and 150 mg?1, respectively, and large differences in the rain characteristics. Various measures are used to contrast evolution of macroscopic cloud field characteristics, such as the mean cloud fraction, the mean cloud width, or the height of the center of mass of the cloud field, among others. Macroscopic characteristics appear similar regardless of the aerosol characteristics or the homogeneity of the subgrid-scale mixing. 相似文献
110.
The ASTER Global Digital Elevation Model (GDEM) has made elevation data at 30 m spatial resolution freely available, enabling reinvestigation of morphometric relationships derived from limited field data using much larger sample sizes. These data are used to analyse a range of morphometric relationships derived for dunes (between dune height, spacing, and equivalent sand thickness) in the Namib Sand Sea, which was chosen because there are a number of extant studies that could be used for comparison with the results. The relative accuracy of GDEM for capturing dune height and shape was tested against multiple individual ASTER DEM scenes and against field surveys, highlighting the smoothing of the dune crest and resultant underestimation of dune height, and the omission of the smallest dunes, because of the 30 m sampling of ASTER DEM products. It is demonstrated that morphometric relationships derived from GDEM data are broadly comparable with relationships derived by previous methods, across a range of different dune types. The data confirm patterns of dune height, spacing and equivalent sand thickness mapped previously in the Namib Sand Sea, but add new detail to these patterns. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献