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671.
It is shown that an outgoing null radiation field in the outer space of a Kerr-Newman black hole is darkened by the rotation of the black hole. This rotational darkening is calculated for a spheroid emitting null radiation normally to its surface, yielding the von Zeipel-like effectthat the equatorial region is darkened more strongly than the polar regions.This effect is not confined to the case of black holes but is also observable for relativistically rotating fluid spheroids such as atmospheres of pulsars or neutron stars. Moreover, application to Hawking radiation suggests that the black hole cannot be viewed as a classical black body but that the Hawking radiationis a global geometric effect. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
672.
The discrimination between electrolytic and electronic conductors is highly relevant to geological modelling as it allows conclusions to be drawn about the formation and mineral composition of rocks. The induced polarization (IP) method, which compares the electric current injected into the ground with the corresponding earth potential differences can be used for this purpose.
  This paper describes a new method based on the theory that non-linear electrochemical processes on the surface of electronic conductors are responsible for non-linear IP (NLIP) phenomena. This results in multiples of the fundamental frequency being observed in the telluric voltage spectra when a monochromatic current signal is fed into the ground. The non-linearity of the current–voltage characteristic is most effectively described by a spectral method.
  A laboratory experiment was carried out, using an electrolytic trough with a small graphite cylinder serving as an electronic conductor, which clearly demonstrated the validity of the method. A field experiment was undertaken at a borehole of approximately 450  m depth, located in the transition zone of the Tepla-Barrandium and Moldanubicum in East Bavaria. A sinusoidal current was injected into the ground using a logging tool at depths varying between 150 and 450  m. The corresponding potential differences were simultaneously observed along a profile on the surface. Field and laboratory results show a striking similarity. It can be concluded that an extensive electronic conductor—probably graphite—is steeply dipping southwards meeting the borehole at approximately 310  m depth.  相似文献   
673.
A large-eddy simulation (LES) model has been used to study a nocturnalstratocumulus-topped marine atmospheric boundary layer. The main objectivesof our study have been first to investigate the statistical significance of LES-derived data products. Second, to test the sensitivity of our LES results with respect to the representation of subgrid-scale mixing and microphysical processes, and third to evaluate and to quantify the parametric uncertainty arising from the incomplete knowledge of the environmental parameters that are required to specify the initial and boundary conditions of a particular case study. Model simulations were compared with observations obtained in solid stratocumulus during the third flight of the first 'Lagrangian' experiment of the Atlantic Stratocumulus Transition Experiment (ASTEX). Based on these simulations the following conclusions could be drawn. Resolution(50 × 50 × 25 m3) and domain size (3.2 × 3.2 × 1.5 km3) of the LES calculations were adequate from a numerical point of view to represent the essential features of the stratocumulus-topped boundary layer. However, the ensemble runs performed in our study to investigate the statistical significance of LES-derived data products demonstrate that the area-time averaging procedure for the second-order moments produces only a low degree of statistical reliability in the model results. This illustratesthe necessity of having LES model results that are not only of adequate resolution but also of sufficiently large domain. The impact of different subgrid schemes was small, but the primary effects of drizzle were found to influence the boundary-layer structure in a climatologically significant way. The parametric uncertainty analysis revealed that the largest contribution to the variance of the LES-derived data products is due to theuncertainties in the cloud-top jump of total water mixing ratio and the net radiative forcing. The differences between the model and measurements for most of the simulated quantities were within the modelling uncertainties, but the calculated precipitation rate was found to differ significantly from that derived in the observations.  相似文献   
674.
The annual temperature stratification of five mining lakes within the Eastern part of Germany was surveyed in the years 1997 and 1998. An intercomparison of the field data of daily average temperatures showed that surface temperatures of all five lakes ran in parallel throughout the year. Differences between lakes were smaller than the interannual variability of a single lake. This indicated that surface temperature could be considered a climatic magnitude only weakly depending on the particular mixing characteristics within the lakes, and thus would be suited for a boundary condition in numerical models. Under certain conditions, surface temperature data could be transferred from one lake to another, if the data set for a numerically modelled lake, e.g. for prognostication purposes, were incomplete or only very short.  相似文献   
675.
Quantitative analysis of melt and fluid inclusions by LA-ICP-MS: Practical aspects and selected resultsAudétatA.,GüntherD.,andHeinrichC.A.1998.Formation of a m agm atic- hydrothermal ore deposit:Insights withL A-ICP-MS analysis of fluid inclusions.Science,279:2091~2094 AudétatA .,GüntherD.,andHeinrichC.A.2000 a.Causes for large- scale m etal zonation around mineralized plutons:FluidinclusionL A-ICP-MS evidence from theMoleGranite,Australia.EconomicGeology,(in press) …  相似文献   
676.
677.
Planning the use of fish for food security in the Pacific   总被引:1,自引:0,他引:1  
Fish is a mainstay of food security for Pacific island countries and territories (PICTs). Recent household income and expenditure surveys, and socio-economic surveys, demonstrate that subsistence fishing still provides the great majority of dietary animal protein in the region. Forecasts of the fish required in 2030 to meet recommended per capita fish consumption, or to maintain current consumption, indicate that even well-managed coastal fisheries will only be able to meet the demand in 6 of 22 PICTs. Governments of many PICTs will need to increase local access to tuna, and develop small-pond aquaculture, to provide food security. Diversifying the supply of fish will also make rural households in the Pacific more resilient to natural disasters, social and political instability, and the uncertainty of climate change.  相似文献   
678.
Research in developing countries concerning the relationship of weather and climate conditions with tourism shows a high importance not only because of financial aspects but also an important part of the region’s tourism resource base. Monthly mean air temperature, relative humidity, precipitation, vapor pressure, wind velocity, and cloud cover for the period 1985–2005 data collected from four meteorological stations Tabriz, Maragheh, Orumieh, and Khoy were selected. The purpose of this study is to determine the most suitable months for human thermal comfort in Ourmieh Lake, a salt sea in the northwest of Iran. To achieve this, the cooling power and physiologically equivalent temperature (PET) calculated by the RayMan model and the Climate Tourism/Transfer Information Scheme (CTIS) were used. The results based on cooling power indicate that the most favorable period for tourism, sporting, and recreational activities in Ourmieh Lake is between June and October and based on PET between June to September. In addition, the CTIS shows a detailed quantification of the relevant climate–tourism factors.  相似文献   
679.
Aerosol number fluxes are spectrally analyzed using fast Fourier transform analysis, wavelet analysis and multiresolution decomposition. All three methods yield similar spectral features in general, although a detailed evaluation of the cospectra shows some differences, e.g. due to different resolutions in the time and frequency domains. Wavelet analysis yields aerosol flux estimates with a high time resolution that can be used to assess the flux variability. Multiresolution decomposition has been applied successfully to evaluate cospectra of the aerosol number flux, the buoyancy flux and the momentum flux of three 1-day datasets from diverse environments. For all scalars and all environments, the dimensionless frequency (f) of the cospectral peak was found between $f = 0.1$ and 0.2. In addition, the cospectral gap time scale of the aerosol number flux was found between 100 and 1,000 s. Thus, in this study several spectral features such as the dominant time scale and the cospectral gap time scale of aerosol number fluxes are similar to buoyancy fluxes. However, the shape of aerosol number flux cospectra often deviates from buoyancy and momentum flux cospectra, especially at very small and at very large time scales.  相似文献   
680.
Relying on a recent survey of more than 3400 participants from China, Germany, and the US, this article empirically analyses citizens' perceptions of key guiding principles for sharing mitigation costs across countries, justification of climate policy and trust in climate policy. Our findings suggest that the ranking of the main principles for burden-sharing is identical in China, Germany, and the US: accountability followed by capability, egalitarianism, and sovereignty. Thus, on a general level, citizens across these countries seem to have a common (normative) understanding of fairness. We therefore find no evidence that citizens' (stated) fairness preferences are detrimental to future burden-sharing agreements. In all three countries a majority of citizens considers international climate policy to be justified, but citizens' perceptions differ across specific items and countries. Finally, a substantial portion of citizens in all countries exhibit a lack of trust in international climate agreements.

Policy relevance

Disagreement over the distribution of mitigation costs across countries is blocking current negotiations about a new international climate change agreement to be adopted in 2015. At the heart of this disagreement are different perceptions of distributive justice among those involved in climate policy making. Our findings show that there is no difference in the ranking of fairness principles across citizens in China, Germany, and the US, suggesting that the common ground for crafting a future agreement is larger than expected. In particular, the accountability principle should weigh heavily when deciding on the burden-sharing. In addition, our findings suggest that in order to gain support among citizens, international climate policy may need to take measures to improve trust.  相似文献   

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