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Atle Christer Christiansen 《Climate Policy》2003,3(4):343-358
The objective of this paper is to assess recent developments and prospects for future changes in United States (US) climate strategy. In doing so, the paper explores some of the key factors that have shaped strategies and policies to date, distinguishing between factors related to institutional and governance structures, linkages between science and policy, energy technology and the role of interest groups. Against this background, the paper attempts to explore future development paths for US climate policy. More specifically, the paper assesses opportunities for policy changes compared to the preferences of the current administration, and the prospects for future linkages between US and international climate change strategies. In brief, the paper argues that substantial changes are unlikely to take place in the near to medium term, leaving open, however, the possibility of wide-ranging changes in domestic politics or major incidents that could facilitate a shift in the perceived need for near-term action. 相似文献
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An important issue in the tomographic reconstruction of the solar poles is the relatively rapid evolution of the polar plumes.
We demonstrate that it is possible to take into account this temporal evolution in the reconstruction. The difficulty of this
problem comes from the fact that we want a four-dimensional reconstruction (three spatial dimensions plus time) whereas we
only have three-dimensional data (two-dimensional images plus time). To overcome this difficulty, we introduce a model that
describes polar plumes as stationary objects whose intensity varies homogeneously with time. This assumption can be physically
justified if one accepts the stability of the magnetic structure. This model leads to a bilinear inverse problem. We describe
how to extend linear inversion methods to these kinds of problems. Studies of simulations show the reliability of our method.
Results for SOHO/EIT data show that we can estimate the temporal evolution of polar plumes to improve the reconstruction of
the solar poles from only one point of view. We expect further improvements from STEREO/EUVI data when the two probes will
be separated by about 60°. 相似文献
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