European temperature records of the past five centuries based on documentary/instrumental information compared to climate simulations     

Eduardo Zorita  Anders Moberg  Lotta Leijonhufvud  Rob Wilson  Rudolf Brázdil  Petr Dobrovolný  Jürg Luterbacher  Reinhard Böhm  Christian Pfister  Dirk Riemann  Rüdiger Glaser  Johan Söderberg  Fidel González-Rouco 《Climatic change》2010,101(1-2):143-168

Two European temperature reconstructions for the past half-millennium, January-to-April air temperature for Stockholm (Sweden) and seasonal temperature for a Central European region, both derived from the analysis of documentary sources and long instrumental records, are compared with the output of climate simulations with the model ECHO-G. The analysis is complemented by comparisons with the long (early)-instrumental record of Central England Temperature (CET). Both approaches to study past climates (simulations and reconstructions) are burdened with uncertainties. The main objective of this comparative analysis is to identify robust features and weaknesses in each method which may help to improve models and reconstruction methods. The results indicate a general agreement between simulations obtained with temporally changing external forcings and the reconstructed Stockholm and CET records for the multi-centennial temperature trend over the recent centuries, which is not reproduced in a control simulation. This trend is likely due to the long-term change in external forcing. Additionally, the Stockholm reconstruction and the CET record also show a clear multi-decadal warm episode peaking around AD 1730, which is absent in the simulations. Neither the reconstruction uncertainties nor the model internal climate variability can easily explain this difference. Regarding the interannual variability, the Stockholm series displays, in some periods, higher amplitudes than the simulations but these differences are within the statistical uncertainty and further decrease if output from a regional model driven by the global model is used. The long-term trend of the CET series agrees less well with the simulations. The reconstructed temperature displays, for all seasons, a smaller difference between the present climate and past centuries than is seen in the simulations. Possible reasons for these differences may be related to a limitation of the traditional ‘indexing’ technique for converting documentary evidence to temperature values to capture long-term climate changes, because the documents often reflect temperatures relative to the contemporary authors’ own perception of what constituted ‘normal’ conditions. By contrast, the amplitude of the simulated and reconstructed inter-annual variability agrees rather well.  相似文献   

SOHO/SUMER observations and analysis of hydrogen Lyman lines in a quiescent prominence     

Schmieder  B.  Heinzel  P.  Vial  J.C.  Rudawy  P. 《Solar physics》1999,189(1):109-127

A quiescent prominence was observed in June 1997 by instruments onboard the SOHO spacecraft: the Solar Ultraviolet Measurements of Emitted Radiation (SUMER), Coronal Diagnostic Spectrometer (CDS) and Extreme-Ultraviolet Imaging Telescope (EIT), along with the coronagraph of the Wrocaw University Observatory at Bialków and the spectrograph of the Ondejov Observatory. We present prominence observations in higher lines of the hydrogen Lyman series (from L to L-9), together with some other UV lines obtained by SUMER. We extract the basic characteristics of the calibrated line profiles of these Lyman lines and compare them with the theoretical profiles computed from three kinds of NLTE models which also include prominence filamentation. Our principal result is that the current NLTE models are in principle capable of explaining the SUMER calibrated intensities in the observed Lyman lines. We also find that in order to fit all these lines, one has to consider a prominence-corona transition region (PCTR) with a temperature gradient. At low pressures, higher Lyman lines are still rather sensitive to the incident radiation which must be carefully taken into account in the modeling. From PCTR models, which also take into account the effect of ambipolar diffusion on the heating, we have derived the formation depths for the Lyman series lines. High Lyman lines seem to be formed just at the base of the PCTR.  相似文献   

The telluric field in a halfspace with a spherical inhomogeneity     

Milan Hvoždara  Reviewer V. Petr 《Studia Geophysica et Geodaetica》1973,17(2):131-143

Summary An exact solution of the distribution of the intensity of the telluric field in a halfspace with a spherical inhomogeneity has been obtained by solving the Laplace equation in bipolar coordinates. This exact solution is compared with the presently known approximate solution, obtained by the method of images, and the region of their coincidence has been determined. For the image solution theoretical relations have been derived for computing the anomaly of the magnetic field. Craphs depict many of the properties of the telluric and magnetic fields on the surface of the considered halfspace for various parameters of the given problem.Dedicated to 90th Birthday of Professor Frantiek Fiala  相似文献   

A contribution to the theory of electromagnetic induction of a line source     

Václav Bezvoda  Karel Segeth  Reviewer V. Petr 《Studia Geophysica et Geodaetica》1976,20(4):366-377

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Four-dimensional modeling of recent vertical movements in the area of the southern california uplift     

Petr Vaníc&#x;ek  Michael R. Elliott  Robert O. Castle 《Tectonophysics》1979,52(1-4)

This paper describes an analytical technique that utilizes scattered geodetic relevelings and tide-gauge records to portray Recent vertical crustal movements that may have been characterized by spasmodic changes in velocity. The technique is based on the fitting of a time-varying algebraic surface of prescribed degree to the geodetic data treated as tilt elements and to tide-gauge readings treated as point movements. Desired variations in time can be selected as any combination of powers of vertical movement velocity and episodic events. The state of the modeled vertical displacement can be shown for any number of dates for visual display. Statistical confidence limits of the modeled displacements, derived from the density of measurements in both space and time, line length, and accuracy of input data, are also provided. The capabilities of the technique are demonstrated on selected data from the region of the southern California uplift.  相似文献   

Petrology of a portion of the Mare Fecunditatis regolith     

Petr Jakesˇ 《Earth and Planetary Science Letters》1972

1300 microprobe analyses of glasses, pyroxenes, feldspars, oxides, olivines, troilite and metal in two 0.025 g samples of the Luna 16 return were made in order to characterize the Mare Fecunditatis regolith.  相似文献   

Global Warming and the Greenland Ice Sheet     

Petr Chylek  Jason E. Box  Glen Lesins 《Climatic change》2004,63(1-2):201-221

The Greenland coastal temperatures have followed the early 20th century global warming trend. Since 1940, however, the Greenland coastal stations data have undergone predominantly a cooling trend. At the summit of the Greenland ice sheet the summer average temperature has decreased at the rate of 2.2 °C per decade since the beginning of the measurements in 1987. This suggests that the Greenland ice sheet and coastal regions are not following the current global warming trend. A considerable and rapid warming over all of coastal Greenland occurred in the 1920s when the average annual surface air temperature rose between 2 and 4 °C in less than ten years (at some stations the increase in winter temperature was as high as 6 °C). This rapid warming, at a time when the change in anthropogenic production of greenhouse gases was well below the current level, suggests a high natural variability in the regional climate. High anticorrelations (r = ?0.84 to?0.93) between the NAO (North Atlantic Oscillation) index and Greenland temperature time series suggest a physical connection between these processes. Therefore, the future changes in the NAO and Northern Annular Mode may be of critical consequence to the future temperature forcing of the Greenland ice sheet melt rates.  相似文献   

The orthometric height and the holonomity problem     

Fernando Sansò  Petr Vanícek 《Journal of Geodesy》2006,80(5):225-232

When height networks are being adjusted, many geodesists advocate the approach where the adjustment should be done by using geopotential numbers rather than the orthometric or normal heights used in practice. This is based on a conviction that neither orthometric nor normal heights can be used for the adjustment because these height systems are not holonomic, meaning–among other things–that height increments (orthometric or normal) when summed around a closed loop do not sum up to zero. If this was the case, then the two height systems could not be used in the adjustment; the non-zero loop closure would violate the basic, usually unspoken, assumption behind the adjustment, namely that the model claiming that height differences are observable is correct. In this paper, we prove in several different ways that orthometric and normal heights are theoretically just as holonomic as the geopotential numbers are, when they are obtained from levelled height differences using actual gravity values. This disposes of the argument that geopotential numbers should be used in the adjustment. Both orthometric and normal heights are equally qualified to be used in the adjustment directly.  相似文献   

Book Review : Wavelet Theory and Harmonic Analysis in Applied Sciences. Edited by C.E. d'Attellis and E.M. Fernández-Berdaguer. Birkhäuser, Boston - Basel - Berlin, 1997, 102 figs., 7 tabs., xviii + 345 pp., hard cover     

Petr Holota 《Studia Geophysica et Geodaetica》1998,42(4):569-570

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Foreign Direct Investment in the Czech Republic     

Petr Pavlínek 《The Professional geographer》1998,50(1):71-85

This paper evaluates foreign direct investment (FDI) in the Czech Republic and its regional development consequences after the collapse of state socialism. Two types of FDIs are identified: cross border export-oriented investments and market capture investments. The cross border export-oriented investments exploit low cost labor in the service of external markets and are typically concentrated in peripheral areas, mostly along the former West German border. This type of FDI is not likely to contribute to durable regional economies. The market capture investments involve both servicing the Czech market and integrating activities within a larger, multinational corporate network. This type of investment may create more durable sources of regional economic activity. A case study of the Volkswagen/Skoda joint venture is used to examine market capture investments and their consequences for regional development. This paper is based on interviews with plant managers and trade union leaders in companies with foreign investment, governmental officials at the various ministries and state agencies dealing with FDI, and information and data from the secondary sources.  相似文献