Search

We analyze the Earth’s surface temperature recorded at available 7 european meteorological stations with 300 years-long activity. We detect variations at several time scales, present in these recordings, namely decadal, inter-decadal (20-30 years), and sub-centennial (60-90 years). These are corelatable with the solar activity variations at the same time scales, indicating a source - effects relationship between the solar input and the air surface temperatures. First, the decadal variations, of amplitudes of ~1° C, are separated from a trend by a Hodrick and Prescott (1997) type analysis, then the inter-decadal and the sub-centennial variations (of several tenths and, respectively, ~1° C amplitude) are separated from the trend by Butterworth (1930) filtering. The analysis is coroborated with similar ones applied to (1) the Danube river discharge as an integrator of temperature and precipitation in the Central Europe and (2) to solar activity monitored or reconstructed parameters., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

This study addresses the causal links between external factors and the main hydro-climatic variables. There is a gap in the literature on the description of a complete chain in addressing the structures of direct causal links of solar activity on the terrestrial variables. This is why, the present study uses the extensive facilities of the application of information theory in view of recent advances in different fields. Also, by other methods (e.g. neural networks) first are tested the existence non-linear links of solar-terrestrial influences on hydro-climate system. The results are promising related to the solar impact on terrestrial phenomena which is discriminant in space-time domain. The implications prove robust for determining the causal measure of climate variables under direct solar impact which makes it easier to consider solar activity in climate models, by appropriate parametrizations. This study found that hydro-climatic variables are sensitive to solar impact only for certain frequencies (periods) and these have a coherence with the Solar-Flux only for some lags of the Solar-Flux (in advance).

The external geomagnetic field, arising from the magnetospheric and ionospheric current systems, developed at the interaction of solar wind and heliospheric magnetic field with the Earth’s magnetic field, especially geomagnetic storms, might induce hazardous response as shown by the surface electric field, the geophysical input in assessing ground space weather impact of geomagnetically induced currents (GICs). In this study, several space weather events are analyzed both from point of view of solar cause and from point of view of near-Earth/ground effects. The surface electric field, induced by the variable magnetic field of geomagnetic storms, is determined based on the geomagnetic field recordings and on information regarding the underground electric conductivity., {"references":["Adam A., Pracser E., Wesztergom V. (2012). Estimation of the electric resistivity distribution (EURHOM) in the European lithosphere in the frame of the EURISGIC WP2 project. Acta Geod. Geoph. Hung., 47, pp 377-387","Viljanen A., Pirjola R. (1989). Statistics on geomagnetically-induced currents in the Finnish 400 kV Power system based on recordings of geomagnetic variations. J. Geomag. Geoelectr., 41, pp 411-420"]}

A field in which progress has recently been made regards deciphering the relationship between the evolution of the geomagnetic field and the Earth’s rotation. Fluctuation in the Earth’s rotation rate (or spin rate) is expressed by the so-called excess length of day (ΔLOD), i.e. variations from the sidereal day. The rotation of the solid Earth changes as a result of applied external torques, internal mass redistribution (in which we include the time dependent fluid convection in the outer core), and the hydrodynamic or magneto-hydrodynamic stresses acting at the fluid/solid Earth interfaces. Generally, the Earth’s rotation is governed by the conservation of the angular momentum of the Earth, with transfers between the solid part (inner core plus mantle) and fluid volumes in contact with (atmosphere and oceans, on one hand, and outer core, on the other). A detailed account on LOD variations can be found in the review papers of Gross (2007) and Dehant and Mathews (2007)., {"references":["Dehant V., Mathews P. M. (2007). Earth Rotation Variations, in Schubert, G., Ed.-in-Chief, Treatise on Geophysics, vol.3, Herring T., Ed., Geodesy, pp. 295-391","Demetrescu C., Dobrica V. (2014). Multi-decadal ingredients of the secular variation of the geomagnetic field. Insights from long time series of observatory data, Phys. Earth Planet. Inter., 231, pp. 29-55","Dobrica V., Demetrescu C., Mandea M. (2018). Geomagnetic field declination: from decadal to centennial scales. Solid Earth, 9, pp. 491-503","Gross, R. S. (2007). Earth Rotation Variation – Long Period, in Schubert, G., Ed.-in-Chief, Treatise on Geophysics, vol.3, Herring T., Ed., Geodesy, pp 239-293","Hodrick, R. J., Prescott, E. C. (1997), Postwar U. S. business cycles: An empirical investigation. J. Money, Credit, Banking, 29, pp. 1-16","Huang, N. E., Shen, Z., Long, S. R., Wu, M. C., Shih, H. H., Zheng, Q., Tung, C. C., Liu, H. H. (1988), The empirical mode decomposition and the Hilbert spectrum for nonlinear and non stationary tme series analysis, Proc. R. Soc. Lond. A,454, pp. 903-995","Le Mouël, J.-L, Madden, T. R., Ducruix, J., Courtillot, V. (1981). Decade fluctuations in geomagnetic westward drift and Earth rotation, Nature, 290, 30 April 1981","Roberts, P. H., Yu, Z., Russell, C. (2007), On the 60-year signal from the core, Geophys. Astrophys. Fluid Dyn., 101, pp. 11-35","Zatman, S., Bloxham, J. (1997). Torsional oscillations and the magnetic field within the Earth's core, Nature, 388, pp. 760-763"]}

During its 4th Workshop in Helsinki in 2009 the Group for European Repeat Station Surveys, MagNetE, decided to produce a European Declination Chart 2006 which is based on the numerous magnetic repeat station measurements performed in more than 20 countries in Europe. All surveys were conducted within a relatively short period between 2005 and 2007, the data set consists of declination values of 382 repeat stations and the annual mean values of 42 observatories. These first accorded surveys in Europe, providing hundreds of highly accurate magnetic vector data, can be considered the first geomagnetic survey of Europe. The resulting map shows the magnetic declination, which is of main public interest for navigation purposes.