Testing the larval drift hypothesis in the Baltic Sea: retention versus dispersion caused by wind-driven circulation   总被引：1，自引：2，他引：1  

Hinrichsen  H.-H.; St. John  M.; Aro  E.; Gronkjaer  P.; Voss  R. 《ICES Journal of Marine Science》2001,58(5):973-984

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Climate change,ecosystems and smallholder agriculture in Central America: an introduction to the special issue     

Pablo Imbach  Megan Beardsley  Claudia Bouroncle  Claudia Medellin  Peter Läderach  Hugo Hidalgo  Eric Alfaro  Jacob Van Etten  Robert Allan  Debbie Hemming  Roger Stone  Lee Hannah  Camila I. Donatti 《Climatic change》2017,140(1):1-4

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An Evaluation of Information Meetings as a Tool for Addressing Fear of Large Carnivores     

Maria Johansson  Jens Frank  Ole-Gunnar Støen  Anders Flykt 《社会与自然资源》2017,30(3):281-298

Managing authorities in Scandinavia arrange public information meetings when members of the public express fear because wolves or brown bears approach human settlements. This study aimed to increase the understanding of the potential effect of information meetings on self-reported fear of wolves and brown bears. In total, 198 participants completed questionnaires before and after the information meetings. Nine follow-up interviews were held 1 year later. The quantitative analyses revealed that participants who found the information credible reported a significant increase in social trust and a decrease in vulnerability and fear. The qualitative analyses pointed to the importance of information content and meta-communication, for example, nonverbal cues. It is proposed that, among participants who find the information credible, information meetings may change the appraisal of wolves and brown bears, and therefore they might prove useful as an intervention to address fear of these animals.  相似文献   

Knowledge rationales in human geography: Economic,policy, empowerment,and methodological     

Johanna Hautala  Maria Höyssä 《Norsk geografisk tidsskrift. Norwegian journal of geography》2017,71(5):269-287

The article presents a systematic review of 152 articles in which the concept of knowledge is applied and that are published in international human geography journals. As the importance of knowledge in society is increasing, especially economic geography has taken up the task of reviewing the concept or role of knowledge in geography. However, there is a need for a more nuanced understanding of knowledge in economic geography, drawing more broadly on human geographical research. The authors analyse how the concept of knowledge is understood and applied in contemporary human geography. Their results demonstrate four knowledge rationales: economic, policy, empowerment, and methodological. Each rationale and their combinations display a particular role and purpose for knowledge, as well as a distinct approach to space. Separately, each rationale provides several insights into a more nuanced understanding of specific aspects of knowledge. When combined, the four rationales offer a holistic overview of the field. The authors conclude that the empowerment rationale offers novel methodological choices towards a more nuanced understanding of knowledge in economic geography.  相似文献   

Optimizing a Knowledge-driven Prospectivity Model for Gold Deposits Within Peräpohja Belt,Northern Finland     

V. Nykänen  T. Niiranen  F. Molnár  I. Lahti  K. Korhonen  N. Cook  P. Skyttä 《Natural Resources Research》2017,26(4):571-584

This paper combines knowledge- and data-driven prospectivity mapping approaches by using the receiver operating characteristics (ROC) spatial statistical technique to optimize the process of rescaling input datasets and the process of data integration when using a fuzzy logic prospectivity mapping method. The methodology is tested in an active mineral exploration terrain within the Paleoproterozoic Peräpohja Belt (PB) in the Northern Fennoscandian Shield, Finland. The PB comprises a greenschist to amphibolite facies, complexly deformed supracrustal sequence of variable quartzites, mafic volcanic rocks and volcaniclastic rocks, carbonate rocks, black shales, mica schists and graywackes. These formations were deposited on Archean basement and 2.44 Ga layered intrusions, during the multiple rifting of the Archean basement (2.44–1.92 Ga). Younger intrusive units in the PB comprise 2.20–2.13 Ga gabbroic sills or dikes and 1.98 Ga A-type granites. Metamorphism and complex deformation of the PB took place during the Svecofennian orogeny (1.9–1.8 Ga) and were followed by intrusions of post-orogenic granitoids (1.81–1.77 Ga). The recent mineral exploration activities have indicated several gold-bearing mineral occurrences within the PB. The Rompas Au-U mineralization is hosted within deformed and metamorphosed calc-silicate veins enclosed within mafic volcanic rocks and contains uranium-bearing zones without gold and very high-grade (>10,000 g/t Au) gold pockets with uraninite and uraninite-pyrobitumen nodules. In the vicinity of the Rompas, a magnesium skarn hosted disseminated-stockwork gold mineralization was also recognized at the Palokas-Rajapalot prospect. The exploration criteria translated into a fuzzy logic prospectivity model included data derived from regional till geochemistry (Fe, Cu, Co, Ni, Au, Te, K), high-resolution airborne geophysics (magnetic field total intensity, electromagnetic, gamma radiation), ground gravity and regional bedrock map (structures). The current exploration licenses and exploration drilling sites for gold were used to validate the knowledge-driven mineral prospectivity model.  相似文献   

Relationships between GPS-signal propagation errors and EISCAT observations     

N. Jakovvski  E. Sardon  E. Engler  A. Jungstand  D. Klähn 《Annales Geophysicae》1997,14(12):1429-1436

When travelling through the ionosphere the signals of space-based radio navigation systems such as the Global Positioning System (GPS) are subject to modifications in amplitude, phase and polarization. In particular, phase changes due to refraction lead to propagation errors of up to 50 m for single-frequency GPS users. If both the LI and the L2 frequencies transmitted by the GPS satellites are measured, first-order range error contributions of the ionosphere can be determined and removed by difference methods. The ionospheric contribution is proportional to the total electron content (TEC) along the ray path between satellite and receiver. Using about ten European GPS receiving stations of the International GPS Service for Geodynamics (IGS), the TEC over Europe is estimated within the geographic ranges –20° 40°E and 32.5° ø 70°N in longitude and latitude, respectively. The derived TEC maps over Europe contribute to the study of horizontal coupling and transport processes during significant ionospheric events. Due to their comprehensive information about the high-latitude ionosphere, EISCAT observations may help to study the influence of ionospheric phenomena upon propagation errors in GPS navigation systems. Since there are still some accuracy limiting problems to be solved in TEC determination using GPS, data comparison of TEC with vertical electron density profiles derived from EISCAT observations is valuable to enhance the accuracy of propagation-error estimations. This is evident both for absolute TEC calibration as well as for the conversion of ray-path-related observations to vertical TEC. The combination of EISCAT data and GPS-derived TEC data enables a better understanding of large-scale ionospheric processes.  相似文献   

Eit and LASCO Observations of the Initiation of a Coronal Mass Ejection   总被引：2，自引：0，他引：2  

K. P. Dere  G. E. Brueckner  R. A. Howard  M. J. Koomen  C. M. Korendyke  R. W. Kreplin  D. J. Michels  J. D. Moses  N. E. Moulton  D. G. Socker  O. C. St. Cyr  J. P. Delaboudinière  G. E. Artzner  J. Brunaud  A. H. Gabriel  J. F. Hochedez  F. Millier  X. Y. Song  J. P. Chauvineau  J. P. Marioge  J. M. Defise  C. Jamar  P. Rochus  R. C. Catura  J. R. Lemen  J. B. Gurman  W. Neupert  F. Clette  P. Cugnon  E. L. Van Dessel  P. L. Lamy  A. Llebaria  R. Schwenn  G. M. Simnett 《Solar physics》1997,175(2):601-612

We present the first observations of the initiation of a coronal mass ejection (CME) seen on the disk of the Sun. Observations with the EIT experiment on SOHO show that the CME began in a small volume and was initially associated with slow motions of prominence material and a small brightening at one end of the prominence. Shortly afterward, the prominence was accelerated to about 100 km s^-1 and was preceded by a bright loop-like structure, which surrounded an emission void, that traveled out into the corona at a velocity of 200–400 km s^-1. These three components, the prominence, the dark void, and the bright loops are typical of CMEs when seen at distance in the corona and here are shown to be present at the earliest stages of the CME. The event was later observed to traverse the LASCO coronagraphs fields of view from 1.1 to 30 R⊙. Of particular interest is the fact that this large-scale event, spanning as much as 70 deg in latitude, originated in a volume with dimensions of roughly 35" (2.5 x 10⁴ km). Further, a disturbance that propagated across the disk and a chain of activity near the limb may also be associated with this event as well as a considerable degree of activity near the west limb.  相似文献   

ALPEX-Simulation     

Prof. Dr. H. Pichler  Prof. Dr. R. Steinacker  E. Hagenauer  A. Jäger 《Meteorology and Atmospheric Physics》1995,56(3-4):197-208

Summary In a project ALPEX-Simulation, sponsored by the Österreichischer Fond zur Förderung der wissenschaftlichen Forschung (FWF), all eight cases of ALPEX-SOP cyclones were numerically simulated with a fine mesh isentropic model of the atmosphere. These numerical simulations in six-hourly intervals allow a deeper insight into the synoptics and dynamics of the cyclogeneses in the Western Mediterranean, especially into the genesis of the two basic types of cyclones: the so-called Überströmungs-type and Vorderseiten-type. In the first phase of cyclogenesis of the Überströmungs-type, the blocking and flow splitting of the cold air due to the Alps and the canalization between the Alps and the Massif Central are important. Cold air flows cyclonically around the western part of the Alps, creating a vorticity maximum at the south western edge of the Alpine, bow and leads also to an enhanced PV. In connection with warm air in the Mediterranean, a strong baroclinic zone is generated. The interaction between the arriving PV maximum in the upper troposphere and the enhanced PV at the bottom leads to cyclogenesis in the Western Mediterranean. In the case of the Vorderseiten-type warm air advection dominates with the exception of a shallow layer of cold air in the inner Po-Valley, which is shielded by the Alpine ridge. A well-pronounced PV maximum builds up and couples with the PV maximum arriving at upper levels, even before the cold air, coming from the north-west, has surrounded the Alps. The cold air only intensifies the development by raising the baroclinity. Therefore, the Vorderseiten-cyclogenesis is an orographically modified cyclogenesis, in the course of which the cyclonic development is triggered by the Alps, whereas the Überströmungs-cyclogenesis is an orographically induced cyclogenesis i.e. a true lee cyclogenesis.With 14 FiguresDied in a tragic traffic accident on June 6, 1993.  相似文献   

Sio observations of mass-losing AGB stars     

B. Aringer  G. Wiedemann  H. U. Käufl  J. Hron 《Astrophysics and Space Science》1995,224(1-2):421-422

We have observed the first overtone rotation-vibration absorption bands of SiO near = 4µm for a sample of 23 oxygen-rich Mira and Semiregular variables using the ESO NTT and IRSPEC. We discuss the strength of the SiO absorption in terms of the near infrared, IRAS and pulsational properties of the stars. Especially among the Miras there are big differences in the strength of the SiO bands between individual objects, which are probably due to pulsational variability.This work is supported by the Austrian Science Fund Project P9638-AST.  相似文献   

Monte Carlo climate change forecasts with a global coupled ocean-atmosphere model   总被引：1，自引：0，他引：1  

U. Cubasch  B. D. Santer  A. Hellbach  G. Hegerl  H. Höck  E. Maier-Reimer  U. Mikolajewicz  A. Stössel  R. Voss 《Climate Dynamics》1994,10(1-2):1-19

Four time-dependent greenhouse warming experiments were performed with the same global coupled atmosphere-ocean model, but with each simulation using initial conditions from different snapshots of the control run climate. The radiative forcing — the increase in equivalent CO₂ concentrations from 1985–2035 specified in the Intergovernmental Panel on Climate Change (IPCC) scenario A — was identical in all four 50-year integrations. This approach to climate change experiments is called the Monte Carlo technique and is analogous to a similar experimental set-up used in the field of extended range weather forecasting. Despite the limitation of a very small sample size, this approach enables the estimation of both a mean response and the between-experiment variability, information which is not available from a single integration. The use of multiple realizations provides insights into the stability of the response, both spatially, seasonally and in terms of different climate variables. The results indicate that the time evolution of the global mean warming signal is strongly dependent on the initial state of the climate system. While the individual members of the ensemble show considerable variation in the pattern and amplitude of near-surface temperature change after 50 years, the ensemble mean climate change pattern closely resembles that obtained in a 100-year integration performed with the same model. In global mean terms, the climate change signals for near surface temperature, the hydrological cycle and sea level significantly exceed the variability among the members of the ensemble. Due to the high internal variability of the modelled climate system, the estimated detection time of the global mean temperature change signal is uncertain by at least one decade. While the ensemble mean surface temperature and sea level fields show regionally significant responses to greenhouse-gas forcing, it is not possible to identify a significant response in the precipitation and soil moisture fields, variables which are spatially noisy and characterized by large variability between the individual integrations.  相似文献