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Developing countries must consider the influence of anthropogenic dynamics on changes in rangeland habitats. This study explores happened degradation in 178 rangeland management plans for Northeast Iran in three main steps: (1) conducting a trend analysis of rangeland degradation and anthropogenic dynamics in 1986-2000 and 2000-2015, (2) visualizing the effects of anthropogenic drivers on rangeland degradation using bivariate local spatial autocorrelation (BiLISA), and (3) quantifying spatial dependence between anthropogenic driving forces and rangeland degradation using spatial regression approaches. The results show that 0.77% and 0.56% of rangelands are degraded annually during the first and second periods. The BiLISA results indicate that dry-farming, irrigated farming and construction areas were significant drivers in both periods and grazing intensity was a significant driver in the second period. The spatial lag (SL) model (wi=0.3943, Ei=1.4139) with two drivers of dry-farming and irrigated farming in the first period and the spatial error (SE) model (wi=0.4853, Ei=1.515) with livestock density, dry-farming and irrigated farming in the second period showed robust performance in quantifying the driving forces of rangeland degradation. To conclude, the BiLISA maps and spatial models indicate a serious intensification of the anthropogenic impacts of ongoing conditions on the rangelands of northeast Iran in the future. 相似文献
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By W. VON HOYNINGEN-HUENE T. DINTER A. A. KOKHANOVSKY J. P. BURROWS M. WENDISCH E. BIERWIRTH D. MÜLLER M. DIOURI 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):206-215
Main optical characteristics of desert dust, such as phase function and single scattering albedo, have been derived from combinations of sun-/sky-radiometer and satellite measurements during the SAMUM experiment (10 May–10 June 2006) at the site Porte au Sahara (30.237°N, 5.607°W) in South Morocco. Scattering phase functions have been retrieved using combined data of spectral aerosol optical thickness (AOT) and spectral sky brightness in the almucantar, considering non-spherical light scattering. Intercomparisons of modelled top-of-atmosphere (TOA) reflectance with satellite observations of the Medium Resolution Imaging Spectrometer (MERIS) and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography () instrument have been used for the estimation of spectral single scattering albedo. For the radiative transfer calculations scattering phase functions and AOT from ground-based observations have been used. The spectral single scattering albedo ranges from 0.93 in the blue to 0.98 at 753 nm. 相似文献
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By RALPH KAHN REAS PETZOLD MANFRED WENDISCH EIKE BIERWIRTH TILMAN DINTER MICHAEL ESSELBORN MARCUS FIEBIG BIRGIT HEESE PETER KNIPPERTZ DETLEF MÜLLER ALEXANDER SCHLADITZ WOLFGANG VON HOYNINGEN-HUENE 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):239-251
Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05–0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape and single-scattering albedo. For the three study days, the satellite observations (1) highlight regional gradients in the mix of dust and background spherical particles, (2) identify a dust plume most likely part of a density flow and (3) show an aerosol air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometres away. 相似文献
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In a paper presented at last year's Amsterdam meeting (viz. Geophysical Prospecting 14 (1966), 3, 301–341), J. R. Schopper derived formulas relating formation factor, permeability and porosity, by means of a statistical-network approach and by treating the electric and hydraulic resistance analogously. The model of the porous medium consists of a network of branch resistors, their values being statistically distributed about a mean Ro with a relative standard deviation (variation coefficient) s. A properly defined total resistance R of the network can be expressed by the relationship: ((1′)) Here α is a geometrical factor dependent only on the shape of the network (i.e. the number of meshes in the longitudinal and transversal direction), ε is a characteristical constant dependent only on the individual mesh shape (i.e. the number of nodes and branches within a mesh). This network constant ε enters the equations relating formation factor, permeability and porosity, ε had been found to be in the range zero to one by calculating algebraically two special limiting network cases. However, for a better understanding of which value exactly this constant will have in actual porous media, networks with various mesh shapes have to be treated generally. Because of the basically statistical approach, the networks have to be large so that a general algebraic treatment is precluded. Hence numerical methods using digital computers must be applied. The determination of the total resistance R of any resistance network leads to the problem of solving a system of linear, inhomogeneous equations; i.e. Ohm's law written in matrix form: ((2′))
- (R) is the matrix of the coefficients, composed of the individual branch resistances.
- (I) is the column vector, its components being fictitious circular mesh currents.
- (U) is the inhomogeneity column, its components being source voltages within the individual meshes.
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Eclogite-Blueschist Relationships as Evidenced by Mineral Equilibria in the High-Pressure Metabasic Rocks of Sifnos (Cycladic Islands), Greece 总被引：1，自引：0，他引：1
The northern part of the Cycladic island of Sifnos (Greece)is formed by a coherent sequence of interlayered acid and basicmetavolcanic rocks and metasediments, which underwent a high-pressureblueschist facies metamorphism during the Eocene. The metabasicrocks, including eclogites, blueschists, and actinolite-bearingrocks, are discussed in terms of their mineral assemblages,and bulk-rock and mineral chemistries. Metamorphic conditionsof 470 ? 30 ?C and 15 ? 3 kb are indicated by garnet-omphacitegeothermometry and by the development of deerite in meta-ironstonesand jadeite +quartz in meta-acidites.Mineral textures and systematicelement distributions between coexisting minerals suggest attainmentof chemical equilibrium. A new projection from garnet, epidote,quartz and vapour onto the NaAlO2-Al2O3-CaMgO2 plane is usedto illustrate equilibrium phase relations between omphacite,glaucophane, actinolite, paragonite, and chloritoid. It is demonstratedthat eclogites, blueschists, and actinolite-bearing metabasitesrepresent different bulk-rock compositions that recrystallizedunder the same fluid pressure and temperature conditions. Eclogitescontaining hydrous minerals such as glaucophane, actinolite,phengite, or paragonite in equilibrium with garnet and omphacitecan occur together with blueschists in high-pressure terraneswithout indicating different metamorphic conditions. 相似文献
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Even though sustainable development has been broadly debated, the clean development mechanism (CDM) still lacks sophisticated multi-criteria decision methods for identifying, selecting and assessing CDM project activities from this perspective. Bearing in mind the huge number of CDM projects that are beginning to accumulate as the carbon market gains momentum, and the importance for non-Annex I Parties to keep focused on the sustainability objective, this article aims at developing a tool for prioritizing—within a given group, and once a specific list of sustainable development criteria is agreed upon and given—proposed CDM projects from this sustainable development point of view. We reached the following conclusions: (1) it is important to make a conscious choice of an appropriate way to normalize the sustainability performance data of CDM projects; (2) it is important to make a conscious choice of how to aggregate across multiple attributes; (3) in contrast with conventional multi-criteria assessments, which elicit preferences from a stakeholder panel, preference optimization infers from CDM projects' performance data an optimal set of weights that proponents would choose in order to win a competitive selection process. Such preference optimization methods (a) yield sensible results, simulating a range of decision circumstances, (b) avoid conflict and convey impartiality in situations where competing project proponents are likely to clash over objectionable weightings, (c) avoid cognitive overload when the number of CDM projects and/or indicators is overwhelmingly large, and (d) circumvent time-consuming and costly interviews and surveys. From a policy perspective, the multi-criteria assessment described here can be a powerful tool for prioritizing CDM projects (1) when there is a limited amount of grant funding to certain CDM project candidates, and (2) when the decisionmaking process incorporates the CDM objective of promoting sustainable development, in addition to the objective of helping developed countries to meet part of their reduction obligations as specified in Annex I of the Protocol. 相似文献
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By EIKE BIERWIRTH MANFRED WENDISCH RÉ EHRLICH BIRGIT HEESE MATTHIAS TESCHE DIETRICH ALTHAUSEN ALEXANDER SCHLADITZ DETLEF MÜLLER SEBASTIAN OTTO THOMAS TRAUTMANN TILMAN DINTER WOLFGANG von HOYNINGEN-HUENE RALPH KAHN ‡ 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):252-269
In May–June 2006, airborne and ground-based solar (0.3–2.2 μm) and thermal infrared (4–42 μm) radiation measurements have been performed in Morocco within the Saharan Mineral Dust Experiment (SAMUM). Upwelling and downwelling solar irradiances have been measured using the Spectral Modular Airborne Radiation Measurement System (SMART)-Albedometer. With these data, the areal spectral surface albedo for typical surface types in southeastern Morocco was derived from airborne measurements for the first time. The results are compared to the surface albedo retrieved from collocated satellite measurements, and partly considerable deviations are observed. Using measured surface and atmospheric properties, the spectral and broad-band dust radiative forcing at top-of-atmosphere (TOA) and at the surface has been estimated. The impact of the surface albedo on the solar radiative forcing of Saharan dust is quantified. In the SAMUM case of 19 May 2006, TOA solar radiative forcing varies by 12 W m−2 per 0.1 surface-albedo change. For the thermal infrared component, values of up to +22 W m−2 were derived. The net (solar plus thermal infrared) TOA radiative forcing varies between −19 and +24 W m−2 for a broad-band solar surface albedo of 0.0 and 0.32, respectively. Over the bright surface of southeastern Morocco, the Saharan dust always has a net warming effect. 相似文献