Management of summer-spawning herring off Iceland   总被引：1，自引：0，他引：1  

Jakobsson  J.; Stefansson  G. 《ICES Journal of Marine Science》1999,56(6):827-833

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Long range forecasts of Northern Hemisphere 500 mb height fields by ARIMA modesl     

Dr. Thor Jakobsson 《Meteorology and Atmospheric Physics》1979,28(2-3):149-158

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The PT phase relations of a primary oceanite from the Reykjanes peninsula,Iceland     

Sven Maaløe  Sveinn P Jakobsson 《Lithos》1980,13(3):237-246

The field relationships and petrographic features of the oceanites of the Reykjanes peninsula suggest that they might have originated as primary magmas. The principal phase relationships of primary liquids formed by the partial melting of lherzolites are defined. The phase relations obtained for oceanite RE78 between 0 and 30 kbar at dry conditions suggest that the oceanite originated as a primary magma at 25 kbar and 1580°C, and erupted at a temperature near 1300°C.  相似文献   

Recent geological–geomorphological processes on the east Arctic shelf: Results of the expedition of the icebreaker Oden in 2014     

L. I. Lobkovsky  S. L. Nikiforov  R. A. Ananiev  A. V. Khortov  I. P. Semiletov  M. Jakobsson  N. N. Dmitrievskiy 《Oceanology》2015,55(6):926-929

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Performance results of HESP physical model     

Anantha Chanumolu  Sivarani Thirupathi  Damien Jones  Sunetra Giridhar  Deon Grobler  Robert Jakobsson 《Experimental Astronomy》2017,43(1):39-58

As a continuation to the published work on model based calibration technique with HESP(Hanle Echelle Spectrograph) as a case study, in this paper we present the performance results of the technique. We also describe how the open parameters were chosen in the model for optimization, the glass data accuracy and handling the discrepancies. It is observed through simulations that the discrepancies in glass data can be identified but not quantifiable. So having an accurate glass data is important which is possible to obtain from the glass manufacturers. The model’s performance in various aspects is presented using the ThAr calibration frames from HESP during its pre-shipment tests. Accuracy of model predictions and its wave length calibration comparison with conventional empirical fitting, the behaviour of open parameters in optimization, model’s ability to track instrumental drifts in the spectrum and the double fibres performance were discussed. It is observed that the optimized model is able to predict to a high accuracy the drifts in the spectrum from environmental fluctuations. It is also observed that the pattern in the spectral drifts across the 2D spectrum which vary from image to image is predictable with the optimized model. We will also discuss the possible science cases where the model can contribute.  相似文献   

Mantle melting in equilibrium with an Iron–Wüstite–Graphite buffered COH-fluid     

Sigurdur Jakobsson  John R. Holloway 《Contributions to Mineralogy and Petrology》2009,157(2):283-284

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The extreme, red afterglow of GRB 060923A: distance or dust?     

N. R. Tanvir  A. J. Levan  E. Rol  R. L. C. Starling  J. Gorosabel  R. S. Priddey  D. Malesani  P. Jakobsson  P. T. O'Brien  A. O. Jaunsen  J. Hjorth  J. P. U. Fynbo  A. Melandri  A. Gomboc  B. Milvang-Jensen  A. S. Fruchter  M. Jarvis  C. A. C. Fernandes  T. Wold 《Monthly notices of the Royal Astronomical Society》2008,388(4):1743-1750

Gamma-ray bursts (GRBs) are powerful probes of the early Universe, but locating and identifying very distant GRBs remain challenging. We report here the discovery of the K -band afterglow of Swift GRB 060923A, imaged within the first hour post-burst, and the faintest so far found. It was not detected in any bluer bands to deep limits, making it a candidate very high- z burst  ( z ≳ 11)  . However, our later-time optical imaging and spectroscopy reveal a faint galaxy coincident with the GRB position which, if it is the host, implies a more moderate redshift (most likely   z ≲ 2.8  ) and therefore that dust is the likely cause of the very red-afterglow colour. This being the case, it is one of the few instances so far found of a GRB afterglow with high-dust extinction.  相似文献   

Estimating ventilation time scales using overturning stream functions     

Bijoy Thompson  Jonas Nycander  Johan Nilsson  Martin Jakobsson  Kristofer Döös 《Ocean Dynamics》2014,64(6):797-807

A simple method for estimating ventilation time scales from overturning stream functions is proposed. The stream function may be computed using either geometric coordinates or a generalized vertical coordinate, such as potential density (salinity in our study). The method is tested with a three-dimensional circulation model describing an idealized semi-enclosed ocean basin ventilated through a narrow strait over a sill, and the result is compared to age estimates obtained from a passive numerical age tracer. The best result is obtained when using the stream function in salinity coordinates. In this case, the reservoir-averaged advection time obtained from the overturning stream function in salinity coordinates agrees rather well with the mean age of the age tracer, and the corresponding maximum ages agree very well.  相似文献   

Mantle melting in equilibrium with an Iron–Wüstite–Graphite buffered COH-fluid     

Sigurdur Jakobsson  John R. Holloway 《Contributions to Mineralogy and Petrology》2008,155(2):247-256

Partial melting experiments on a San Carlos peridotite were done in a Walker type multi-anvil press at pressures from 5 to 12.5 GPa. Experiments were done in the presence of a COH-fluid and at oxygen fugacity controlled by the Fe–FeO buffer. Olivine, clinopyroxene, garnet and orthopyroxene are stable in all but the highest temperature 10 GPa experiments where olivine and garnet coexist, and the highest temperature 5 GPa experiments where olivine is the single crystalline phase. The solidus at 5 GPa was found to be at approximately 1,200°C and the liquidus was estimated to be at 1,325°C, which is ∼500°C lower than has been reported for dry melting of peridotite. The aluminum concentration of the melts decreases with increasing melt fraction and decreases also with increasing pressure. At 5 GPa the melts have a CaO/Al₂O₃-ratio of 0.85–1.0, which is similar to that of undepleted komatiites; major element concentrations are also identical to those of undepleted komatiites such as the Munro komatiites. At 10 and 12.5 GPa the partial melts have CaO/Al₂O₃-ratios above 1.5 and major element composition almost identical to aluminum depleted komatiites such as the Barberton komatiites. We therefore conclude that in the presence of a reducing COH-fluid both aluminum-depleted and -undepleted komatiites could have formed at temperatures much lower than generally accepted.  相似文献   

Petrology of mugearite-hawaiite: Early extrusives in the 1973 Heimaey eruption,Iceland     

S.P. Jakobsson  A.K. Pedersen  J.G. Rönsbo  L. Melchior Larsen 《Lithos》1973,6(2):203-214

Rocks which erupted during the first few weeks are described and chemical analyses of rocks and microprobe analyses of minerals are presented. An outline of the eruption history and of the geology of the area is given. A gradational change in chemistry from mugearitic to hawaiitic composition is recorded. Xenoliths of hypersthene gabbro not cognate with magma were discovered in the mugearite. One xenolith has reacted with the mugearite magma at depth to form pargasitic hornblende and kaersutite. It is argued that the magma reacted with the xenoliths at a total pressure well below 8–9 kbar and at a gas pressure higher 1 kbar.  相似文献