Climate feedback efficiency and synergy     

Thorsten Mauritsen  Rune G. Graversen  Daniel Klocke  Peter L. Langen  Bjorn Stevens  Lorenzo Tomassini 《Climate Dynamics》2013,41(9-10):2539-2554

Earth’s climate sensitivity to radiative forcing induced by a doubling of the atmospheric CO₂ is determined by feedback mechanisms, including changes in atmospheric water vapor, clouds and surface albedo, that act to either amplify or dampen the response. The climate system is frequently interpreted in terms of a simple energy balance model, in which it is assumed that individual feedback mechanisms are additive and act independently. Here we test these assumptions by systematically controlling, or locking, the radiative feedbacks in a state-of-the-art climate model. The method is shown to yield a near-perfect decomposition of change into partial temperature contributions pertaining to forcing and each of the feedbacks. In the studied model water vapor feedback stands for about half the temperature change, CO₂-forcing about one third, while cloud and surface albedo feedback contributions are relatively small. We find a close correspondence between forcing, feedback and partial surface temperature response for the water vapor and surface albedo feedbacks, while the cloud feedback is inefficient in inducing surface temperature change. Analysis suggests that cloud-induced warming in the upper tropical troposphere, consistent with rising convective cloud anvils in a warming climate enhances the negative lapse-rate feedback, thereby offsetting some of the warming that would otherwise be attributable to this positive cloud feedback. By subsequently combining feedback mechanisms we find a positive synergy acting between the water vapor feedback and the cloud feedback; that is, the combined cloud and water vapor feedback is greater than the sum of its parts. Negative synergies surround the surface albedo feedback, as associated cloud and water vapor changes dampen the anticipated climate change induced by retreating snow and ice. Our results highlight the importance of treating the coupling between clouds, water vapor and temperature in a deepening troposphere.  相似文献   

Late-magmatic immiscibility during batholith formation: assessment of B isotopes and trace elements in tourmaline from the Land’s End granite,SW England   总被引：3，自引：0，他引：3  

Kristian Drivenes  Rune B. Larsen  Axel Müller  Bjørn E. Sørensen  Michael Wiedenbeck  Morten P. Raanes 《Contributions to Mineralogy and Petrology》2015,169(6):1-27

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Metallic mineral deposits in the Nordic countries     

Paer Weihed Pasi Eilu Rune B. Larsen Henrik Stendal Mikko Tontti 《《幕》》2008,31(1):125-132

The Nordic countries, including Greenland, have a long tradition in mining. Documented mining dates back to the 8th century AD. Today this region is the most important metallic mining district of the European Union. Metals are produced from active mines in all countries except Iceland and related industries are thriving in all countries.
Important ore deposit types include： volcanogenic massive sulphide deposits （Cu, Zn, Pb, Au, Ag）, orogenic gold deposits （Au）, layered intrusions （Ni, PGE, Ti±V）, intrusive hosted Cu-Au, apatite-Fe deposits, Cr- and anorthosite hosted Ti deposits. Besides these well- documented deposits, new kinds of deposits are being explored, e.g., iron oxide-copper-gold （IOCG）, shale-hosted Ni-Zn-Cu and different types of uranium deposits.  相似文献   

Laboratory Observation and Micromechanics-Based Modelling of Sandstone on Different Scales     

Liming Li  Idar Larsen  Rune M. Holt 《Rock Mechanics and Rock Engineering》2015,48(4):1407-1422

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The effect of different sweep lengths on the length composition of bottom-sampling trawl catches   总被引：4，自引：4，他引：0  

Engas  Arill; Godo  Olav Rune 《ICES Journal of Marine Science》1989,45(3):263-268

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New identifications of disk emission lines in the Ca ii H and K line wings     

O. Engvold  H. D. Halvorsen 《Solar physics》1973,28(1):23-25

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Elastic Dispersion Derived from a Combination of Static and Dynamic Measurements     

Erling Fjær  Anna M. Stroisz  Rune M. Holt 《Rock Mechanics and Rock Engineering》2013,46(3):611-618

Utilization of laboratory tests for calibration and interpretation of data from seismic surveys requires knowledge about elastic dispersion in the range from seismic to ultrasonic frequencies. Data on such dispersion are hard to obtain because it requires specially designed equipment and also relies on simplifying assumptions about rock symmetry. A new method for estimation of dispersion in this frequency range is presented here. This method requires only standard rock mechanical equipment with ultrasonic velocity measurements, and is based on comparison of static and dynamic data. A key element in this method is a procedure for elimination of strain amplitude as a source for differences between static and dynamic moduli. High-quality data is necessary, but the required accuracy is not extreme. Application of the method on one partly saturated shale and two dry sandstone samples indicates that dispersion increases with clay content, and decreases with stress.  相似文献   

Levels and temporal trends of PCDD/PCDFs and non-ortho PCBs in ringed seals from East Greenland     

Riget F  Vikelsøe J  Dietz R 《Marine pollution bulletin》2005,50(12):1523-1529

The levels and temporal trend of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and non-ortho substituted PCBs (c-PCBs, i.e. CB77, CB126 and CB169) were determined in ringed seal blubber from central East Greenland collected in 1986, 1994, 1999 and 2003, respectively. Since 1986 the concentrations of PCDDs, PCDFs and c-PCBs all show a decreasing trend. The annual decreases were estimated to 5.2% and 5.3% for pg/g WHO-TEQ ww of PCDD/Fs and c-PCB, respectively. The annual median concentrations of PCDDs ranged from 5.4 to 24.4 pg/g WHO-TEQ ww and those of PCDFs from 2.5 to 5.1 pg/g WHO-TEQ ww. Compared to PCDD/Fs concentrations in ringed seals from other Arctic areas the levels of PCDD/Fs found in 1986 were the highest recorded. The annual median concentrations of c-PCBs decreased 24.2 to 9.1 pg/g WHO-TEQ ww. The levels of c-PCBs observed in 1986 are similar to levels found in ringed seals from Svalbard in 1990 and from eastern Hudson Bay in 1989–1992. The dominant and most TEQ-contributing PCDD congener was 1,2,3,7,8-PeCDD. CB126 was the dominating and most TEQ-contributing c-PCB congener. The concentrations of PCDDs, PCDFs and c-PCBs were highly significantly inter-correlated. Principal component analysis of the PCDD/PCDF congeners and c-PCBs was performed to analyse the pattern of compounds during time.  相似文献   

Discrete Element Modeling of Stress and Strain Evolution Within and Outside a Depleting Reservoir   总被引：1，自引：0，他引：1  

Haitham T. I. Alassi  Liming Li  Rune M. Holt 《Pure and Applied Geophysics》2006,163(5-6):1131-1151

Stress changes within and around a depleting petroleum reservoir can lead to reservoir compaction and surface subsidence, affect drilling and productivity of oil wells, and influence seismic waves used for monitoring of reservoir performance. Currently modeling efforts are split into more or less coupled geomechanical (normally linearly elastic), fluid flow, and geophysical simulations. There is evidence (from e.g. induced seismicity) that faults may be triggered or generated as a result of reservoir depletion. The numerical technique that most adequately incorporates fracture formation is the DEM (Discrete Element Method). This paper demonstrates the feasibility of the DEM (here PFC; Particle Flow Code) to handle this problem. Using an element size of 20 m, 2-D and 3-D simulations have been performed of stress and strain evolution within and around a depleting reservoir. Within limits of elasticity, the simulations largely reproduce analytical predictions; the accuracy is however limited by the element size. When the elastic limit is exceeded, faulting is predicted, particularly near the edge of the reservoir. Simulations have also been performed to study the activation of a pre-existing fault near a depleting reservoir.  相似文献   

The Egersund dykes (SW Norway): a robust Early Ediacaran (Vendian) palaeomagnetic pole from Baltica   总被引：3，自引：0，他引：3  

Harald J. Walderhaug  Trond H. Torsvik  Erik Halvorsen 《Geophysical Journal International》2007,168(3):935-948

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