Reconstructing the Palaeoclimate of Jæren, Southwestern Norway, for the Period 1821–1850, from Historical Documentary Records     

Elisabeth Kastellet  Atle Nesje  & Einar Solheim Pedersen 《Geografiska Annaler: Series A, Physical Geography》1998,80(1):51-65

Documentary data provide long time series and sometimes high-resolution, detailed data from historical times to the present and can give valuable information about palaeoclimate, and for the prediction of future climates. In this paper, documentary data containing qualitative information on climate, in the form of a diary written by the farmer I.G. Grude, and two newspapers, were used for the reconstruction of the palaeoclimate at Jæren, in the county of Rogaland, in southwestern Norway, during the period 1821–50. An index method to quantify the qualitative climate data was developed and used for a low-resolution reconstruction of winter, summer and annual temperatures. A high-resolution climate reconstruction of temperature and precipitation for the winter of 1837/38 is also presented, making use of a method that keeps the climate data in a qualitative form. The climate reconstructions are compared to an instrumental temperature series from Bergen, for the same period. The two data sets are in good agreement except for summer temperature (annual temperature: r = 0.75, winter temperature: r = 0.77, summer temperature: r = 0.44). Compared to average temperatures during 1961–90, the instrumental data from Bergen during the 1821–50 period show slightly different temperatures: annual average was 0.3°C lower, winter 0.4°C lower, and summer 0.1°C lower than at present, implying conditions consistent with the "Little Ice Age" climate.  相似文献   

Delayed fractionation of basaltic lavas     

Sven Maaløe  Rolf B. Pedersen  D. James 《Contributions to Mineralogy and Petrology》1988,98(4):401-407

The phenocryst cores of the basaltic lavas from Jan Mayen and Hawaii display a range in compositions. The textural features of the phenocrysts also vary, both euhedral and skeletal phenocrysts are present in the same thin section. Apparently the basaltic magmas underwent crystallization within a temperature interval of 50–200° C before they became fractionated. The fractionates of basaltic lavas are therefore average compositions of the phenocryst assemblages rather than liquidus compositions. This type of fractionation is called delayed fractionation. It is considered that most tholeiitic and alkalic basaltic lavas undergo delayed fractionation.  相似文献   

The origin of oceanic plagiogranites from the karmoy ophiolite,western Norway   总被引：16，自引：0，他引：16  

Rolf B. Pedersen  John Malpas 《Contributions to Mineralogy and Petrology》1984,88(1-2):36-52

Both field relationships and geochemical characteristics indicate two suites of plagiogranitic and related rocks coexisting in the higher parts of the Karmoy ophiolite of western Norway. The plutonic zone of this ophiolite can be subdivided into three complexes; the East-Karmoy Igneous Complex, the Visnes High Level Complex and the Veavagen Igneous Complex and plagiogranitic rocks are well developed in the first two of these.Within the East-Karmoy Igneous Complex, plagiogranites are associated with high temperature, pre-basic dyke, shear zones. Rare earth element modelling indicates that these plagiogranites were derived by anatexis of amphibolite (hydrated diabase) assuming a starting material consisting of 40% hornblende and 60% plagioclase and that batch melting occurred within the stability field of hornblende.In comparison, plagiogranite occurs in a number of bodies in the upper part of the Visnes High Level Complex and forms a sandwich horizon together with biotite diorites and epidosites between a roof assemblage of dykes, microgabbros and magnetite gabbros, and a floor assemblage of layered and non-layered gabbros. The R.E.E. modelling of the petrogenesis of this series of plagiogranites indicates that they were derived by filter pressing of a differentiated interstitial liquid to the vari-textured gabbros, although the distribution of highly hygromagmatophile elements such as K, Rb, Ba, etc. cannot be explained satisfactorily by this model alone. Depletion in these elements appears to be an autometasomatic effect.  相似文献   

Improvement of the photometric sunspot index and changes of thedisk-integrated sunspot contrast with time     

Claus Fröhlich  Judit M. Pap  Hugh S. Hudson 《Solar physics》1994,152(1):111-118

  相似文献   

Airborne VLF Measurements and Variations of Ground Conductivity: A Tutorial     

Laust B. Pedersen  Behrooz Oskooi 《Surveys in Geophysics》2004,25(2):151-181

Airborne very low frequency (VLF) data are routinely collected by national agencies and commercial companies together with other passive geophysical measurements of the static magnetic field and radiometric data. The purpose of this paper is to demonstrate that both standard three-component VLF and tensor VLF (TVLF) data contain a lot of useful quantitative and qualitative information about the electrical conductivity distribution in the upper few hundred meters of the crystalline basement. We first give a new derivation of the fundamental transfer functions (the tipper) used in the TVLF technique. We then show that the tipper can be estimated from simultaneous measurements of the wave magnetic fields from at least two transmitters with somewhat different frequencies, and present a simple model by which the maximum error introduced by the difference in frequencies can be found. Single transmitter scalar VLF maps emphasise those conductive structures that have dominant strikes in the direction of the transmitter. Multiple transmitter transfer functions are dependent only upon the underlying conductivity structure. Two dimensional structures can be quantitatively modelled by modern inversion methods developed originally for deep electromagnetic magnetotelluric (MT) soundings. In such cases three-component VLF measurements can be modelled easily upon appropriate rotation of the co-ordinate system to “strike” co-ordinates. Single frequency transfer functions (tippers) have real and imaginary parts that carry information on not only lateral contrasts in conductivity, as usually stated in text books, but, taken together, they provide a robust tool for determining the background conductivity level away from distinct conductors, and they can also be used to discriminate between deep and shallow conductors. Based upon simulations using multi-frequency data, it can be concluded that such a new development would dramatically increase the resolving power of airborne VLF measurements.  相似文献   

Crustal melting in the lower parts of island arcs: an example from the Bremanger Granitoid Complex,west Norwegian Caledonides   总被引：4，自引：0，他引：4  

Jogvan Hansen  Kjell P. Skjerlie  Rolf B. Pedersen  Jesús De La Rosa 《Contributions to Mineralogy and Petrology》2002,143(3):316-335

  相似文献   

Measuring surface wave phase velocities beneath small broad-band arrays: tests of an improved algorithm and application to the French Alps   总被引：2，自引：0，他引：2  

Helle A. Pedersen  Olivier Coutant  A. Deschamps  M. Soulage  N. Cotte 《Geophysical Journal International》2003,154(3):903-912

  相似文献   

Geomorphic response to active tectonics: Numerical and field‐based approaches          下载免费PDF全文

A. Demoulin  M. Schiattarella  V.K. Pedersen 《地球表面变化过程与地形》2018,43(12):2666-2668

  相似文献   

Data-moderate assessments of Cape monkfish Lophius vomerinus and west coast sole Austroglossus microlepis in Namibian waters     

JN Kathena  A Kokkalis  MW Pedersen  JE Beyer  UH Thygesen 《African Journal of Marine Science》2018,40(3):293-302

There is global interest in providing scientific advice on optimal harvesting of all commercially exploited fish stocks. Nevertheless, many commercially important stocks lack analytical assessments. Therefore, we evaluate a data-moderate stock assessment method: the stochastic surplus production model in continuous time (SPiCT). The method was applied to two Namibian stocks: (i) the data-rich Cape monkfish Lophius vomerinus, where results are compared to a new data-rich assessment using a state–space assessment model (SAM); and (ii) the data-moderate west coast sole Austroglossus microlepis, which is an important bycatch species in the Cape monkfish fishery, but currently unassessed. The information available to the data-moderate assessment is total commercial catch, commercial catch per unit effort (CPUE), and survey CPUE. SPiCT and SAM gave largely consistent estimates of relative fishing mortality (F/F_MSY) and relative exploitable biomass (B/B_MSY) for the Cape monkfish stock, although with some discrepancies. Differences in the biomass estimates between the two assessments suggest that further investigation is required to understand the cause, and that some caution is necessary when considering the biomass of the stock. SPiCT shows that the west coast sole may be overexploited, although the confidence bounds were too wide for a firm conclusion. Similarity in the estimates of F/F_MSY for Cape monkfish in recent years, using SPiCT relative to SAM, likewise indicates the suitability of SPiCT for managing west coast sole.  相似文献   

Discussion of Gabrielsen et al. (2010): Latest Caledonian to Present tectonomorphological development of southern Norway     

S.B. Nielsen  O.R. Clausen  V.K. Pedersen  J.-E. Leseman  B. Goledowski  M. Huuse  K. Gallagher  M.A. Summerfield 《Marine and Petroleum Geology》2010

  相似文献