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111.
Yong Chen Jing Duan Junling An Huizhi Liu Ulrich G?rsdorf Franz H.Berger 《大气和海洋科学快报》2021,14(5):24-29
卫星估雨精度的不确定性受到当地降雨类型和像元内降雨非均匀性影响,而结合这两个关键因素开展半干旱草原卫星估雨的研究有限.2009年夏,我们在中国锡林郭勒半干旱草原用多部微雨雷达和雨量计构建了9 km卫星像元降雨观测网,观测了像元内降雨非均匀性(空间变异系数CV),并评估了卫星估雨精度.结果表明:(1)CV值受像元内平均降雨量,降雨类型,降雨云面积及移向等影响,如高Cv值的降雨过程大多为平均降雨量小,对流性降雨过程,降雨云边缘像元CV值较高;(2)TRMM 3B42V7卫星估雨产品适用性较好,CMORPH和PERSIANN次之,但TRMM 3B42V7易在半干旱草原湖泊处高估降雨. 相似文献
112.
Aude?ValadeEmail authorView author&#;s OrcID profile Sebastiaan?Luyssaert Patrick?Vallet Sylvestre?Njakou Djomo Ingride?Jesus Van Der Kellen Valentin?Bellassen 《Carbon balance and management》2018,13(1):26
Background
Concern about climate change has motivated France to reduce its reliance on fossil fuel by setting targets for increased biomass-based renewable energy production. This study quantifies the carbon costs and benefits for the French forestry sector in meeting these targets. A forest growth and harvest simulator was developed for French forests using recent forest inventory data, and the wood-use chain was reconstructed from national wood product statistics. We then projected wood production, bioenergy production, and carbon balance for three realistic intensification scenarios and a business-as-usual scenario. These intensification scenarios targeted either overstocked, harvest-delayed or currently actively managed stands.Results
All three intensification strategies produced 11.6–12.4 million tonnes of oil equivalent per year of wood-based energy by 2026, which corresponds to the target assigned to French wood-energy to meet the EU 2020 renewable energy target. Sustaining this level past 2026 will be challenging, let alone further increasing it. Although energy production targets can be reached, the management intensification required will degrade the near-term carbon balance of the forestry sector, compared to continuing present-day management. Even for the best-performing intensification strategy, i.e., reducing the harvest diameter of actively managed stands, the carbon benefits would only become apparent after 2040. The carbon balance of a strategy putting abandoned forests back into production would only break even by 2055; the carbon balance from increasing thinning in managed but untended stands would not break even within the studied time periods, i.e. 2015–2045 and 2046–2100. Owing to the temporal dynamics in the components of the carbon balance, i.e., the biomass stock in the forest, the carbon stock in wood products, and substitution benefits, the merit order of the examined strategies varies over time.Conclusions
No single solution was found to improve the carbon balance of the forestry sector by 2040 in a way that also met energy targets. We therefore searched for the intensification scenario that produces energy at the lowest carbon cost. Reducing rotation time of actively managed stands is slightly more efficient than targeting harvest-delayed stands, but in both cases, each unit of energy produced has a carbon cost that only turns into a benefit between 2060 and 2080.113.
114.
Evaluating coastal scenery using fuzzy logic: Application at selected sites in Western Black Sea coastal region of Turkey 总被引：1，自引：0，他引：1
Coastal areas of the world are under treat due to the conflicting requirements of functions such as habitation and/or recreation, which affect the strategic asset of coastal scenery itself. Coastal managers, together with planners, need coastal landscape inventories, where the quality of coastal scenery is a part of the inventory. In order to provide an evidence-based approach for sound coastal management decisions,
[Ergin et al., 2004] and [Ergin et al., 2006] developed a novel technique ‘coastal scenic evaluation’ (CSE), which addresses the evaluation of coastal scenery. The CSE technique utilizes fuzzy logic to derive values obtained from a checklist of 26 physical and human parameters. The methodology enables the calculation of an evaluation index (D), which categorizes the scenic values of coastal sites into five distinct classes. Using this technique, coastal scenic evaluations were carried out at 34 selected sites on the Western Black Sea coast of Turkey. Based on the calculated D values, a five-class differentiation was obtained for the selected sites, to provide baseline information for any envisaged subsequent management plans for these areas. 相似文献
115.
116.
GIS-based assessment of landslide susceptibility on the base of the Weights-of-Evidence model 总被引：4，自引：2，他引：2
The major scope of the study is the assessment of landslide susceptibility of Flysch areas including the Penninic Klippen in the Vienna Forest (Lower Austria) by means of Geographical Information System (GIS)-based modelling. A statistical/probabilistic method, referred to as Weights-of-Evidence (WofE), is applied in a GIS environment in order to derive quantitative spatial information on the predisposition to landslides. While previous research in this area concentrated on local geomorphological, pedological and slope stability analyses, the present study is carried out at a regional level. The results of the modelling emphasise the relevance of clay shale zones within the Flysch formations for the occurrence of landslides. Moreover, the distribution of mass movements is closely connected to the fault system and nappe boundaries. An increased frequency of landslides is observed in the proximity to drainage lines, which can change to torrential conditions after heavy rainfall. Furthermore, landslide susceptibility is enhanced on N-W facing slopes, which are exposed to the prevailing direction of wind and rainfall. Both of the latter geofactors indirectly show the major importance of the hydrological conditions, in particular, of precipitation and surface runoff, for the occurrence of mass movements in the study area. Model performance was checked with an independent validation set of landslides, which are not used in the model. An area of 15% of the susceptibility map, classified as highly susceptible, “predicted” 40% of the landslides. 相似文献
117.
Paola Malanotte-Rizzoli Roberta E. Young Dale B. Haidvogel 《Dynamics of Atmospheres and Oceans》1989,13(3-4)
The process of combining models of the ocean circulation with large data sets is known in meteorology as model initialization and data assimilation. This process is new to oceanographers, who only now are on the verge of having available world-wide synoptic maps of dynamic variables. In this paper we carry out a series of idealized initialization/assimilation experiments with a primitive equation (PE) model, which constitute a first step in developing a realistic process model and data assimilation techniques for the Gulf Stream system. The PE model is used in a spin-down mode and initialized with an analytic jet profile with geostrophically balanced fields.Two major questions are addressed in the present study. The first concerns the initialization process of a PE model during which internal/inertial gravity wave noise is produced. We ask: are the initialization shocks equally crucial for ocean models as they have been for their atmospheric counterparts? The results of an extensive series of balanced versus unbalanced initializations indicate that, for a PE model with a rigid lid, a brutally unbalanced initialization is required to produce strong internal gravity wave shocks. A geostrophically balanced initialization is sufficient to ensure smooth jet evolutions, with no apparent gravity waves, over long time durations in the spin-down mode. No sophisticated initialization procedures seem, therefore, to be required.The second question addressed is: which component of the flow is the most important in data assimilation to drive the model response towards a baseline reference ocean? We specifically compare the knowledge of the depth-integrated flow only, corresponding to measurements of the total transport, with the knowledge of the density field only, or equivalently the velocity shear. The knowledge of the interior density field is much more effective in decreasing the root-mean-square (r.m.s.) errors relative to the reference ocean. If the baroclinic structure is known, coarse horizontal resolutions of data insertion can be reached before significantly worsening the model estimates. If only the depth-averaged flow is known, a decrease in the horizontal resolution of data assimilation has an immediate effect: the r.m.s. errors sharply increase and the assimilation run diverges from the reference ocean. In the assimilation of the barotropic flow alone, even with dense resolution, the errors in the deep layers always show an increasing trend. The relative effectiveness of baroclinic versus barotropic data insertion can be rationalized in the context of geostrophic adjustment theory. 相似文献
118.
119.
The ability of turbulent nuées ardentes (surges) to transport coarse pyroclasts has been questioned on the basis that settling velocities of coarse fragments in the deposits are much too high for them to have been supported by turbulence in a dilute gas suspension. A computer model is used to evaluate the settling velocity of pyroclasts in suspensions of varying concentration and temperature. Since suspension of grains in low-concentration surges occurs if the shear velocity exceeds the settling velocity, the shear velocities related to the 16th and 84th percentiles, and the mean of the grain-size distribution are compared in surge deposits of the Vulsini, with the shear velocity necessary to move the coarsest grain on the bed surface (the Shields criterion). The results show that the settling velocities do not vary significantly in gaseous suspensions having volume concentrations lower than 15%, and that an increase in concentration to 25% is not sufficient to decrease the settling velocity of the coarser fraction, if it represents flow shear velocity. It is shown that the settling velocity of the mean grain size (M
z
) best depicts the shear velocity of a dilute turbulent suspension. Applying the results to the May 1902 paroxysmal nuées ardentes of Mount Pelée shows that the estimated mean velocities are well within the observed velocities, and sufficient to support all the clasts in dilute, turbulent suspensions. 相似文献
120.
Element Mobility During Incipient Granulite Formation at Kabbaldurga, Southern India 总被引：7，自引：2，他引：7
At Kabbaldurga, infiltration of carbonic fluids along a systemof ductile shears and foliation planes has led to partial transformationof Archaean grey biotite–hornblende gneiss to coarse-grainedmassive charnockite at about 2.5 b.y. ago. The dehydration ofthe gneiss assemblage was induced by a marked metasomatic changeof the reacting system from granodioritic to granitic, and obviouslytook place under conditions of an open system at 700–750?C and 5–7 kb. Extensive replacement of plagioclase (An16–30)by K-feldspar through Na, Ca–K exchange reactions withthe ascending carbonic fluids led to strong enrichment in K,Rb, Ba, and SiO2, and to a depletion in Ca. Progressive dissolutionof hornblende, biotite, magnetite, and the accessory mineralsapatite and zircon resulted in a marked depletion in Fe, Mg,Ti, Zn, V, P, and Zr. Most important is the recognition of REEmobility: with advancing charnockitization, the moderately fractionatedREE distribution patterns of the grey gneisses (LaN270; LaN/YbN= 5–20; EuN27; Eu/Eu* = 0.6–0.3) give way to stronglyfractionated REE patterns with a positive Eu-anomaly (LaN200;LaN/YbN = 20–80; EuN22; Eu/Eu* = 0.6–1.8). The systematicdepletion especially in the HREE is due to the progressive dissolutionof zircon, apatite (and monazite), which strongly concentratethe REE. Stable isotope data (18O of 6.9–8.0 per mille for gneissesand charnockites; 13C of –8.5 and –6.5 per millefor late carbonate) indicate a magmatogenic source for the carbonicfluids. In contrast to the currently favoured derivation ofcarbonic fluids by decarbonation of the upper mantle or degassingof underplated basaltic intrusions, it is discussed here thatabundant fluid inclusions in lower crustal charnockites providedan extensive reservoir of ‘fossil’ carbonic fluids.Shear deformation has tapped this reservoir and generated thechannel-ways for fluid ascent. Charnockitization of the Kabbaldurgatypethus appears to be a metasomatic process which is tectonicallycontrolled and restricted to the crustal level of the amphiboliteto granulite transition. 相似文献