共查询到20条相似文献，搜索用时 31 毫秒
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S. H. Derbyshire 《Boundary-Layer Meteorology》1995,74(1-2):19-54
Selected field measurements of evening stable boundary layers are presented in detail comparable with published Large Eddy Simulation results. Such models appear to match idealized theories more closely than do some boundary-layer observations. Any attempt to compare detailed observations with idealized models therefore highlights the variability of the real boundary layer.Here direct turbulence measurements across the stable boundary layer from a heterogeneous and an ideal site are contrasted. Recommendations are made for the information needed to distinguish heterogeneous and ideal cases.The companion paper (Part II) discusses further the issues of data, analysis in the presence of variability, and the effects of averaging over heterogeneous terrain.Part of UK Meteorological Office Atmospheric Process Research Division. 相似文献
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This paper offers a systematic analysis of the concepts and contexts that frame the climate-smart agriculture (CSA) discourse in the academic and policy literature. Documents (n?=?113) related to CSA and published in peer-reviewed journals, books, working papers, and scientific reports from 2004 to 2016 were reviewed. Three key trends emerged from the analysis: studies are biased towards global policy agendas; research focuses on scientific and technical issues; and the integration of mitigation, adaptation, and food security (the three pillars of CSA) is becoming a popular scholarly solution. Findings suggest that CSA is a fairly new concept used to describe a range of adaptation and mitigation practices without a specific set of criteria. Although CSA is often framed around the three pillars, the underlying issues constructing the discourse differ at global, developing, and developed country scales. Although there is increasing research on developing countries, particularly in relation to how CSA can transform smallholder agriculture, there is a paucity of research documenting the experiences from developed countries. The findings suggest that research on CSA needs to move beyond solely focussing on scientific approaches and only in certain geographical contexts. If CSA is to be applicable for farmers across the globe, then cross-disciplinary research that is underpinned by broad socio-economic and political contexts is essential to understand how differences in narratives might affect implementation on-the-ground in both developing and developed countries.POLICY RELEVANCEAlthough policy makers are increasingly supportive of the climate-smart agriculture (CSA) approach, the rhetoric has largely been developed on the basis of scientific and technical arguments. The political implications of varying perspectives have resulted in a growing divide between how developing and developed countries frame solutions to the impacts of climate change on agriculture under the 2015 Paris Agreement. Different framings are part of the explanation for why the scope of CSA is being rethought, with the scientific community redirecting attention to seeking a separate work programme under the United Nations Framework Convention on Climate Change (UNFCCC). The current policy framing of CSA will give no new policy direction unless it grounds itself in the smallholder farmer and civil society contexts. 相似文献
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Soil Carbon: Policy and Economics 总被引：4，自引：2，他引：4
Agricultural soils provide a prospective way of mitigating the increasing atmospheric concentration of CO2. A number of agricultural practices are known to stimulate the accumulation of additional soil carbon and early indications are that some might sequester carbon at relatively modest costs with generally positive environmental effects. We discuss, under 10 themes, policy and economic issues that will determine whether programs for sequestration of carbon in agricultural soils can succeed. The issues involve contexts for implementation, economics, private property rights, agricultural policy, and institutional and social structures. Ultimately, success will depend on the incentive structure developed and the way in which carbon sequestration is integrated into the total fabric of agricultural policy. 相似文献
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Lightning and climate: A review 总被引：4，自引：0，他引：4
Research on regional and global lightning activity and the global electrical circuit is summarized. This area of activity has greatly expanded through observations of lightning by satellite and through increased use of the natural (Schumann) resonances of the Earth–ionosphere cavity. The global electrical circuit provides a natural framework for monitoring global change on many time scales. Lightning is responsive to temperature on many time scales, but the sensitivity to temperature appears to diminish at the longer time scales. 相似文献
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Ann Henderson-Sellers 《Climatic change》1991,19(1-2):135-137
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S. H. Derbyshire 《Boundary-Layer Meteorology》1995,75(1-2):1-24
As argued in Part I (Derbyshire, 1995), variability is a key issue in stable boundary layers, and differences in variability between observations and idealized models may imply sytematic biases. Here we discuss how data analysis can be geared to allow for variability and thus consistency with models. Instrumental errors, smoothing methods and vertical discretization are considered. We then show how statistical averaging broadly improves the agreement of heterogeneous results in Part I with the Brost-Wyngaard closure. Recommendations are made for the information needed to analyze apparent differences between homogeneous and heterogeneous stable boundary layers.Part of UK Meteorological Office Atmospheric Processes Research Division 相似文献
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Climate change poses formidable challenge to the development of livestock sector in India. The anticipated rise in temperature
between 2.3 and 4.8°C over the entire country together with increased precipitation resulting from climate change is likely
to aggravate the heat stress in dairy animals, adversely affecting their productive and reproductive performance, and hence
reducing the total area where high yielding dairy cattle can be economically reared. Given the vulnerability of India to rise
in sea level, the impact of increased intensity of extreme events on the livestock sector would be large and devastating for
the low-income rural areas. The predicted negative impact of climate change on Indian agriculture would also adversely affect
livestock production by aggravating the feed and fodder shortages. The livestock sector which will be a sufferer of climate
change is itself a large source of methane emissions, an important greenhouse gas. In India, although the emission rate per
animal is much lower than the developed countries, due to vast livestock population the total annual methane emissions are
about 9–10 Tg from enteric fermentation and animal wastes. 相似文献
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Decentralization, forests and livelihoods: Theory and narrative 总被引：3，自引：0，他引：3
This paper discusses the theory of decentralized forest management, the associated narrative and the underlying hypotheses. That discussion informs the assessment of whether decentralization can lead to forest conservation. The paper argues that the ideal model of democratic decentralization described in the literature is unlikely to be implemented given the governance constraints present in many tropical forest countries. Even if that model could be implemented, it is shown that decentralization cannot be expected to necessarily lead to forest conservation. The policies required to complement the current decentralization model are discussed, including financial incentives and monitoring and evaluation mechanisms. 相似文献
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Ozone mixing ratios observed by the Bordeaux microwave radiometer between 1995 and 2002 in an altitude range 25–75 km show diurnal variations in the mesosphere and seasonal variations in terms of annual and semi-annual oscillations (SAO) in the stratosphere and in the mesosphere. The observations with 10–15 km altitude resolution are presented and compared to photochemical and transport model results.Diurnal ozone variations are analyzed by averaging the years 1995–1997 for four representative months and six altitude levels. The photochemical models show a good agreement with the observations for altitudes higher than 50 km. Seasonal ozone variations mainly appear as an annual cycle in the middle and upper stratosphere and a semi-annual cycle in the mesosphere with amplitude and phase depending on altitude. Higher resolution (2 km) HALOE (halogen occultation experiment) ozone observations show a phase reversal of the SAO between 44 and 64 km. In HALOE data, a tendancy for an opposite water vapour cycle can be identified in the altitude range 40–60 km.Generally, the relative variations at all altitudes are well explained by the transport model (up to 54 km) and the photochemical models. Only a newly developed photochemical model (1-D) with improved time-dependent treatment of water vapour profiles and solar flux manages to reproduce fairly well the absolute values. 相似文献
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区间系统与区间优化模型是一种应用广泛的描述不确定性问题的数学模型.本文综述区间系统与区间优化模型在理论与应用方面的研究进展.特别地,本文将介绍区间线性系统的解和可解性问题、区间线性优化模型的最优解和最优性问题以及区间二次优化模型的最优解和最优性问题,最后简单概述它们的各种应用实例. 相似文献
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Climate Change and Agricultural Soils: Impacts and Adaptation 总被引：8，自引：1，他引：7
This article reviews the current state of knowledge on the response of soils to climate change, and the implications such changes have for agriculture. The article is based on the material reported in the IPCC second assessment report (Watson et al., 1996) and updated with more recent information, where appropriate. The review highlights the importance of understanding the dynamics of soil processes when addressing climate change impacts on agriculture. Rapid soil responses to climate change (e.g. soil water, organic carbon and erodibility) have been widely investigated and reported in the literature. However, it is important that longer-term processes (e.g. pedogenesis) are not ignored by the research community because these have potentially important implications for long-term agricultural land use and are often irreversible. The use of good land management practices, as currently understood, provides the best strategy for adaptation to the impact of climate change on soils. However, it appears likely that farmers will need to carefully reconsider their management options, and land use change is likely to result from different crop selections that are more appropriate to the changing conditions. Perhaps the greatest impact of climate change on soils will arise from climate-induced changes in land use and management. 相似文献
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We outline the theoretical and political background to the global carbon mechanisms and how they emerged in the form of the Kyoto Protocol??s Clean Development Mechanism, Joint Implementation, and Intergovernmental Emissions Trading. We present empirical data on the response to date and the variants that have arisen. Based on this, we analyse the issues and evidence on the main controversies around additionality, efficiency and effectiveness of the instruments. The final part of the paper considers some of the implications for future development. 相似文献
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Ralph J. Cicerone 《Climatic change》2006,77(3-4):221-226
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国际地圈-生物圈计划研究进展和展望 总被引：5，自引：0，他引：5
作为全球变化研究的主要核心计划,经过15年的研究,国际地圈一生物圈计划(IGBP)已经进入了第2研究阶段。文章综述了IGBF,计划近10年研究进展,主要有地球系统关键过程研究和跨计划的集成研究两方面。面对未来的挑战与机遇,在研究方向上IGBP将发生变动,包括实现更高层次上的集成研究,与全球可持续发展相适应,从理论研究走向实际应用,全球问题与区域问题结合更加明确等4方面。同时按照地球系统的结构,指出了对应地球系统各圈层及界面的相关计划研究的热点问题,并介绍了我国IGBP研究的主要成果与未来研究方向。 相似文献