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811.
Christophe Hissler Núria Martínez-Carreras François Barnich Laurent Gourdol Jean François Iffly Jérôme Juilleret Julian Klaus Laurent Pfister 《水文研究》2021,35(5):e14140
The Weierbach experimental catchment (0.45 km2) is the most instrumented and studied sub-catchment in the Alzette River basin in Luxembourg. Within the last decade, it has matured towards an interdisciplinary critical zone observatory focusing on a better understanding of hydrological and hydro-geochemical processes. The Weierbach catchment is embedded in an elevated sub-horizontal plateau, characterized by slate bedrock and representative of the Ardennes Massif. Its climate is semi-marine, with precipitation being rather evenly distributed throughout the year. Base flow is lowest from July to September, essentially due to higher losses through evapotranspiration in summer. The regolith is composed of Devonian slates, overlaid by Pleistocene slope deposits and entirely covered by forest with 70% deciduous and 30% coniferous trees. Since 2009, the Weierbach has been extensively equipped for continuously monitoring water fluxes and physico-chemical parameters within different compartments of the critical zone. Additionally, these compartments are sampled fortnightly at several locations to analyze δ18O and δ2H isotopic composition of water including rainfall, throughfall, soil water, groundwater and streamwater. This ongoing monitoring and sampling programme is used for answering pressing questions related to fundamental catchment functions of water infiltration, storage, mixing and release in forest ecosystems. A recently started research line aims at investigating interactions between forest eco-hydrosystems with the atmosphere and understanding how catchments will respond to a non-stationary climate. 相似文献
812.
We use an integrated assessment model of climate change to analyze how alternative decision-making criteria affect preferred investments into greenhouse gas mitigation, the distribution of outcomes, the robustness of the strategies, and the economic value of information. We define robustness as trading a small decrease in a strategy’s expected performance for a significant increase in a strategy’s performance in the worst cases. Specifically, we modify the Dynamic Integrated model of Climate and the Economy (DICE-07) to include a simple representation of a climate threshold response, parametric uncertainty, structural uncertainty, learning, and different decision-making criteria. Economic analyses of climate change strategies typically adopt the expected utility maximization (EUM) framework. We compare EUM with two decision criteria adopted from the finance literature, namely Limited Degree of Confidence (LDC) and Safety First (SF). Both criteria increase the relative weight of the performance under the worst-case scenarios compared to EUM. We show that the LDC and SF criteria provide a computationally feasible foundation for identifying greenhouse gas mitigation strategies that may prove more robust than those identified by the EUM criterion. More robust strategies show higher near-term investments in emissions abatement. Reducing uncertainty has a higher economic value of information for the LDC and SF decision criteria than for EUM. 相似文献
813.
Boris Shustov Mikhail Sachkov Ana I. Gómez?de?Castro Klaus Werner Norbert Kappelmann Alexander Moisheev 《Astrophysics and Space Science》2011,335(1):273-282
Continuous access to the UV domain has been considered of importance to astrophysicists and planetary scientists since the
mid-sixties. However, the future of UV missions for the post-HST era is believed by a significant part of astronomical community
to be less encouraging. We argue that key science problems of the coming years will require further development of UV observational
technologies. Among these hot astrophysical issues are: the search for missing baryons, revealing the nature of astronomical
engines, properties of atmospheres of exoplanets as well as of the planets of the Solar System etc. We give a brief review
of UV-missions both in the past and in the future. We conclude that UV astronomy has a great future but the epoch of very
large and efficient space UV facilities seems to be a prospect for the next decades. As to the current state of the UV instrumentation
we think that this decade will be dominated by the HST and coming World Space Observatory-Ultraviolet (WSO-UV) with a 1.7 m
UV-telescope onboard. The international WSO-UV mission is briefly described. It will allow high resolution/high sensitivity
imaging and high/low resolution spectroscopy from the middle of the decade. 相似文献
814.
XIN Yufei Annette RINKE BIAN Lingen Klaus DETHLOFF XIAO Cunde Moritz MIELKE 《大气科学进展》2010,27(6):1453-1472
Climate and forecast mode simulations with the regional climate model
HIRlam-ECHAM(HIRHAM) are evaluated over a pan-Antarctic domain. The ability
of the model to simulate temperature and wind profiles in the troposphere is
quantified by comparing its results with radiosonde data acquired from the
Davis station for January and July 2007. Compared to the climate mode, the
forecast mode was found to deliver improved results for temperature and wind
simulations at the near surface and in the lower troposphere. The main
remaining model bias found was the under-representation of low-level wind
jets. Based on ensemble simulations, it is shown that a distinct internal
variability is inherent in the climate mode simulations, and associated
areas of reduced predictability over Antarctica are identified. 相似文献
815.
816.
Two kinds of objective functions for parameter optimisation in simplified general circulation models (SGCMs) are introduced
and tested with an SGCM employing linear parameterisations for diabatic heating, surface friction and horizontal diffusion.
(a) A set of circulation indices is introduced to characterise the zonal mean primary and secondary circulation and the global
energetics. The objective function is then given by the distance between the modelled and a reference (e.g. observed) circulation
in a state space spanned by these indices. (b) The global and time mean entropy production and kinetic energy dissipation
are introduced as additional objective functions, following the maximum entropy production principle. It is found that both
methods lead to optimal parameter values close to the standard configuration of the model, though the method of the second
kind is restricted to those model parameters associated with internal processes such as heat and momentum fluxes. 相似文献
817.
818.
Klaus M. Meyer-Abich 《Climatic change》1980,2(4):373-385
Prevention of climatic change by changing human economic behaviour or compensation for climatically detrimental effects by technological fixes is not necessarily better than adaptation. In fact, there are good reasons to conclude that adaptation is the most rational political option, at the same time requiring least marginal action. The problems arising from CO2 all appear at present to be marginal ones which arise, and should be taken care of, for other reasons as well. With respect to CO2-induced changes we could not do better than do what should be done in any event for reasons of development policy.Editor's Note: This paper is, in part, a result of interactions at the U.S. Department of Energy's interdisciplinary workshop on Environmental and Societal Consequences of a Possible CO2-induced Climatic Change, Annapolis, Maryland, April, 1979. Although it is more of a discussion draft than a formal paper, it is being published rapidly and in its present form, for the reason it was written: to generate discussion, debate and exchange on the very important, yet hardly explored, question of societal response to CO2. Comments on this paper, or its subject, would be welcomed. 相似文献
819.
Klaus Keil Gayle Lux D.G. Brookins Elbert A. King Trude V.V. King Eugene Jarosewich 《Meteoritics & planetary science》1978,13(1):11-22
Inman (find, 1966) is a single, relatively unweathered stone of 7.25 kg that contains fresh metal and only few weathering products away from fractures. It has a pronounced chondritic texture, with 38 vol % of the meteorite being made up of chondrules of virtually all textural types. The recalculated bulk analysis, particularly the ratios of Fetotal/SiO2 (0.46), Fe°/Fetotal (0.35), and Fe°/Ni° (6.67) and the contents of Fetotal (19.45%) and metallic nickel-iron (7.94%), indicate that Inman is an L-group chondrite. The pronounced chondritic texture; the compositional variabilities of olivine, pyroxene, chromite, and ilmenite; the presence of a fine-grained, nearly opaque matrix, glass and twinned monoclinic low-Ca pyroxene indicate that the chondrite belongs to petrologic type 3. 相似文献
820.
In the following paper we argue that each wind-driving star in relative motion with respect to the ambient interstellar medium experiences a force exerted on its central wind-generating body. The exact magnitude of this force depends on the actual geometry of the counterflow configuration of stellar and interstellar winds for a particular kinematic situation which is especially sensitive to whether the interstellar flow is subsonic or supersonic. It will, however, be demonstrated here that this force is of an accelerating nature, i.e., it operates like a rocket-motor, as long as the peculiar motion of the wind-driving star with respect to the ambient interstellar medium remains subsonic.Here we use a specific analytical model to describe theoretically the specific counterflow configuration for the case of the solar system in a subsonic peculiar motion with respect to the local interstellar medium assuming irrotational and incompressible flows. We can work out a quantitative number for the accelerating force governing the Sun's motion at present. The net reaction force exerted on the solar body is then mediated by the asymmetric boundary conditions to which the distant solar wind field has to adapt.Next we study the indirect action of such a force on orbiting Keplerian objects like planets, planetesimals and comets. Since this force only influences the central solar body, but not the planets themselves, the problem is different from the treatment of a constant perturbation force perturbing the Keplerian orbits. We present a perturbation analysis treating the action of a corresponding position-dependent perturbation force resulting in secular changes of the orbital elements of Keplerian objects. It is found that changes are accumulating more rapidly in time the closer to the sun the orbiting bodies are. Main axis and perihelion distances are systematically increasing. Especially pronounced are changes in the perihelion position angle of the objects. For solar wind mass losses larger than the Sun's present value by a factor of 1000 (T-Tauri phase of the Sun,) the migration periods calculated for the planet Mercury are of the same order of magnitude as that for corresponding general relativistic migration. 相似文献