Modeling of prominence threads in magnetic fields: Levitation by incompressible MHD waves     

Pécseli  Hans  Engvold  OddbjØrn 《Solar physics》2000,194(1):73-86

The nature of thin, highly inclined threads observed in quiescent prominences has puzzled solar physicists for a long time. When assuming that the threads represent truly inclined magnetic fields, the supporting mechanism of prominence plasma against gravity has remained an open issue. This paper examines the levitation of prominence plasma exerted by weakly damped MHD waves in nearly vertical magnetic flux tubes. It is shown that the wave damping, and resulting `radiation pressure', caused predominantly by ion-neutral collisions in the `cold' prominence plasma, may balance the acceleration of gravity provided the oscillation frequency is 2 rad s^–1 (f0.5 Hz). Such short wave periods may be the result of small-scale magnetic reconnections in the highly fragmentary magnetic field of quiescent prominences. In the proposed model, the wave induced levitation acts predominantly on plasma – neutral gas mixtures.  相似文献   

The heat goes on—changes in indices of hot extremes in Poland     

Graczyk  Dariusz  Pińskwar  Iwona  Kundzewicz  Zbigniew W.  Hov  Øystein  Førland  Eirik J.  Szwed  Małgorzata  Choryński  Adam 《Theoretical and Applied Climatology》2017,129(1-2):459-471

Theoretical and Applied Climatology - On the basis of temperature observations at 60 meteorological stations in Poland, changes in the indices associated with the presence of extremely high air...  相似文献   

Basin modelling: Advances and applications, Stavanger, Norway, 13–15 March 1991     

Anthony G. Dor  Christian Hermanrud   yvind Sylta  Jan H. Augustson 《Marine and Petroleum Geology》1991,8(4)

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Comparison of geomorphological field mapping and 2D‐InSAR mapping of periglacial landscape activity at Nordnesfjellet,northern Norway          下载免费PDF全文

Markus Eckerstorfer  Harald Øverli Eriksen  Line Rouyet  Hanne H. Christiansen  Tom Rune Lauknes  Lars Harald Blikra 《地球表面变化过程与地形》2018,43(10):2147-2156

The ability to continuously monitor the dynamic response of periglacial landforms in a climate change context is of increasing scientific interest. Satellite radar interferometry provides information on surface displacement that can be related to periglacial processes. Here we present a comparison of two‐dimensional (2D) surface displacement rates and geomorphological mapping at periglacial landform and sediment scale from the mountain Nordnesfjellet in northern Norway. Hence, 2D Interferometric Synthetic Aperture Radar (InSAR) results stem from a 2009–2014 TerraSAR‐X dataset from ascending and descending orbits, decomposed into horizontal displacement vectors along an east–west plane, vertical displacement vectors and combined displacement velocity. Geomorphological mapping was carried out on aerial imagery and validated in the field. This detailed landform and sediment type mapping revealed an altitudinal distribution dominated by, weathered bedrock blockfields, surrounded primarily by slightly, to non‐vegetated solifluction landforms at the mountain tops. Below, an active rockslide and associated rockfall deposits are located on the steep east‐facing side of the study area, whereas glacial sediments dominate on the gentler western side. We show that 2D InSAR correctly depicts displacement rates that can be associated with typical deformation patterns for flat‐lying or inclined landforms, within and below the regional permafrost limit, for both wet and dry areas. A net lowering of the entire landscape caused by general denudation of the periglacial landforms and sediments is here quantified for the first time using radar remote sensing. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

The 14th international workshop on wave hindcasting and forecasting and the 5th coastal hazards symposium     

Øyvind Breivik  Jose Henrique Alves  Diana Greenslade  Kevin Horsburgh  Val Swail 《Ocean Dynamics》2017,67(3-4):551-556

Following the 14th International Workshop on Wave Hindcasting and Forecasting and 5th Coastal Hazards Symposium in November 2014 in Key West, Florida, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 16 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. A general trend in the field has been towards closer integration between the wave and ocean modelling communities. This is also seen in this topical collection, with several papers exploring the interaction between surface waves and mixed layer dynamics and sea ice.  相似文献   

Range and AGC normalization in airborne discrete-return LiDAR intensity data for forest canopies   总被引：1，自引：0，他引：1  

Ilkka Korpela  Hans Ole Ørka  Juha Hyyppä  Ville Heikkinen  Timo Tokola 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(4):369-379

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A re-investigation of the bloom-forming unarmored dinoflagellate Karenia longicanalis (syn. Karenia umbella ) from Chinese coastal waters     

Wang  Jianyan  Cen  Jingyi  Li  Si  Lü  Songhui  Moestrup  Øjvind  Chan  Kin-Ka  Jiang  Tao  Lei  Xiangdong 《中国海洋湖沼学报》2018,36(6):2202-2215

The dinoflagellate genus K arenia is known for recurrent harmful blooms worldwide. However, species diversity of the genus is generally overlooked owing to the difficulty of identifying small unarmored dinoflagellates. We have established four clonal cultures of K arenia longicanalis isolated from the type locality, Hong Kong harbor(strain HK01) and other three locations along the Chinese coasts(strains YB01, DT01, and NJ01). The morphology of the strain was studied by light and scanning electron microscopy(LM and SEM) and the pigment composition analyzed by high-performance liquid chromatography. We provide the first molecular data of K. longicanalis based on the large subunit(LSU) rRNA gene sequence and internal transcribed spacer(ITS). The four strains showed identical LSU rDNA sequences with a similarity of 99.4% to the holotype of K arenia umbella(strain KUTN05) from Australia. In the ITS phylogeny, the sequence of K. umbella branched between the Chinese strains of K. longicanalis. A careful comparison of the morphology of K. longicanalis and K. umbella reveals the similarity in the diagnostic characters. Diff erences may appear due to the sample treatment for SEM. We conclude that K. umbella is a junior synonym of K. longicanalis.  相似文献   

Cultural barriers to climate change adaptation: A case study from Northern Burkina Faso   总被引：1，自引：0，他引：1  

Jonas Østergaard Nielsen  Anette Reenberg 《Global Environmental Change》2010,20(1):142-152

Human adaptation to climate change is a heterogeneous process influenced by more than economic and technological development. It is increasingly acknowledged in the adaptation to climate change literature that factors such as class, gender and culture play a large role when adaptation strategies are either chosen or rejected at the local scale. This paper explores adaptation strategies by focusing on livelihood diversification in the face of the most recent of recurrent droughts in the Sahel. It is shown that for Fulbe, one of the two main ethnic groups in the small village in Northern Burkina Faso studied, culture acts as a major barrier to embracing four of the most successful livelihood strategies: labour migration, working for development projects, gardening, and the engagement of women in economic activities.  相似文献   

Geological modeling and simulation of CO2 injection in the Johansen formation     

Geir Terje Eigestad  Helge K. Dahle  Bjarte Hellevang  Fridtjof Riis  Wenche Tjelta Johansen  Erlend Øian 《Computational Geosciences》2009,13(4):435-450

The Johansen formation is a candidate site for large-scale CO₂ storage offshore of the south-western coast of Norway. An overview of the geology for the Johansen formation and neighboring geological formations is given, together with a discussion of issues for geological and geophysical modelling and integrated fluid flow modelling. We further describe corresponding simulation models. Major issues to consider are capacity estimation and processes that could potentially cause CO₂ to leak out of the Johansen formation and into the formations above. Currently, these issues can only be investigated through numerical simulation. We consider the effect of different boundary conditions, sensitivity with respect to vertical grid refinement and permeability/transmisibility data, and the effect of residual gas saturations, since these strongly affect the CO₂-plume distribution. The geological study of the Johansen formation is performed based on available seismic and well data. Fluid simulations are performed using a commercial simulator capable of modelling CO₂ flow and transport by simple manipulation of input files and data. We provide details for the data and the model, with a particular focus on geology and geometry for the Johansen formation. The data set is made available for download online.  相似文献   

Time-resolved high-resolution spectroscopy of the pulsating sdB star QQ Vir (PG1325+101)     

J. Telting  R. Østensen  R. Oreiro  U. Heber  M. Vučković  S. Randall  A. Baran 《Astrophysics and Space Science》2010,328(1-2):163-166

In this work, a standard solar model is computed with new reaction rates that take into account the exact astrophysical S-factor, S _e for the ³He(³He,2p)⁴He, ³He(α,γ)⁷Be and ⁷Be(p,γ)⁸B reactions. The exact S-factor which is valid for all energies is an improved version of the S-factor in the lower-energy approximation (Yusof and Kassim in Astrophys. Space Sci., 2009b). The effects of these new nuclear reaction rates on the solar neutrino fluxes are then discussed by comparing this model to a solar model computed with the standard NACRE reaction rates (Angulo et al. in Nucl. Phys. A. 656:3, 1999). The new reaction rates are found to decrease the neutrinos flux for ⁷Be and ⁸B by about 6% and 16%, respectively. A solar model is also computed with the reaction rates of the LUNA collaboration for ¹⁴N(p,γ)¹⁵O (Formicola et al. in Phys. Lett. B 591:61, 2004). In this case, a clear decrease of the fluxes for ¹³N and ¹⁵O is observed to be in good agreement with previous results (see e.g. Bahcall et al. in Astrophys. J. 621:L88, 2005).  相似文献