Long-term solar activity and terrestrial connections. Part II: at the beckon of the sun?

The research task described herein aims at the structuring of an analytical tool that traces the time course of geophysical phenomena, regional or global, and compares it to the course of long-term solar conditions, long-term meaning decades or a few centuries. The model is based on the premise that since in a last analysis the preponderance of atmospheric, hydrospheric, and, possibly, some aspects of geospheric phenomena are, or have been, powered by energy issuing from the sun – either now or in the past – the long-term behavior of such phenomena is ultimately connected to long-term changes occurring in the sun itself. Accordingly, the proposed research firstly derives and models a stable surrogate pattern for the long-term solar activity, secondly introduces a transfer-function algorithm for modeling the connection between the surrogate and terrestrial phenomena viewed as partners in the connection, and thirdly probes the connection outcome for episodic or unanticipated effects that may arise due to the fact that in the present context, the connection, should it exist, is very likely nonlinear. Part I of the study presents the theory of the concept, while Part II demonstrates the concepts pertinence to a number of terrestrial phenomena.     

Long-term variations of the solar-geomagnetic correlation,total solar irradiance,and northern hemispheric temperature (1868–1997)

Time series for annual means of sunspot numbers, aa-indices of geomagnetic activity and annual numbers of 3-h time intervals with different values of aa-indices (aa≤4 and aa≥30) from 1868 to 1997 have been examined by the method of running-window cross-correlation analysis. It has been found that the solar-geomagnetic correlation varies over time. In particular, long-term variations of the 23-year running correlation appear to have a quasi periodicity of about 40–50 years, superposed on a linear trend, where the trend describes a general decrease of the 23-year running-window correlation between 1868 and the present. Long-term variations of the solar-geomagnetic correlation may result from the quasi-periodic fluctuations of the time lag of geomagnetic indices relative to sunspot numbers, superposed on an upward linear trend of time lag. Secular variations of the northern hemisphere land-air surface temperature anomalies and two solar indices that are potential proxy measures for the total solar irradiance (i.e., the length of the sunspot cycle and the Hoyt and Schatten (Hoyt, D.V., Schatten, K.V., 1993. Journal of Physical Research 98, 18,895–18,906.) composite index) have been compared with the long-term variations of the solar-geomagnetic correlation. The extremum points (points where the derivative vanishes to zero) of these variations are found to occur contemporaneously during the periods of low solar-geomagnetic correlation, suggesting, perhaps, that the long-term variations of solar-geomagnetic correlation are due to some long-term processes on the Sun and that they have a measurable effect on the Earth.     

Daytime VLF emissions at the Sodankyla Observatory (L ∼ 5.3) at the front of high-speed solar wind streams

We discuss the results of an analysis of digital high-sensitivity ground-based observations of very low frequency (VLF) emissions, carried out in Northern Finland (L = 5.3) in May–June 2012. During this period of time, we found that three high-speed solar wind streams approached the Earth’s magnetosphere and at the front of these fluxes long-lasting intense daytime bursts of VLF emissions were generated in two frequency bands: above and below ～2.5 kHz. At frequencies above ～2.5–3.0 kHz, there were VLF hiss waves, the temporal structure of which consisted of a quasi-periodic sequence of separate stronger spots of noise signals. The low-frequency band was represented by chorus waves, superimposed on intense hiss emissions at frequencies below ～1.5 kHz. The high-frequency (f > 2.5 kHz) waves were elliptic and, predominately, left-hand polarized and the low-frequency waves were right-hand polarized. It was supposed that high-frequency VLF hiss waves were generated at L < 5 and VLF chorus waves were generated at L > 5. We discuss a possible scenario of the generation and propagation of the VLF emissions observed.     

Long-term solar wind variations in the 20th–23rd solar activity cycles according to radio-astronomical data

We analyzed the variations of the interplanetary plasma parameters, obtained from radio astronomical observations of scintillations of cosmic radio sources during four 11-year cycles of solar activity, from 1966 to present. It is shown that the state of the interplanetary plasma permanently changes in conformity with cyclicity in the solar activity. In the studied time period, besides the 11-year variations in the velocity and scintillation index, there is also an increasing linear trend of these variables, which is presumably due to a secular 80–90-year cycle of solar activity. The observed differences between the 11-year variations and trends in the solar wind velocity and interplanetary scintillation index suggest that the 11-year and secular cycles have different origins. It is found that these trends occur in this time period in each link of the Sun-Earth system: in the solar activity indices, in the characteristics of the interplanetary medium, and practically in all characteristics of the geophysical, demographical, medical, and other Earth’s processes. From the entire set of facts we can conclude that most of the analyzed Earth’s processes are dominated not by anthropogenic factors, but by the effects of the secular cyclic processes of the solar activity.     

The rigidity spectrum of the harmonics of the 27-day variation of the galactic cosmic ray intensity in different epochs of solar activity: 1965–2002

We study temporal changes of the rigidity (R) spectrum of the harmonics of the 27-day variation of the galactic cosmic ray (GCR) intensity using neutron monitors (NM) data for the period 1965–2002. We show that the rigidity spectrum of the third harmonic (9 days) of the 27-day variation of the GCR intensity changes in a similar way as the spectra of the first and second harmonics, being hard in the maximum epochs and soft in the minimum epochs of solar activity. We ascribe this finding to the alternation of the sizes of the modulation regions of the 27-day variation of the GCR intensity in different epochs of solar activity. The average size of the vicinity of the corotating interaction regions, causing the 27-day variation of the GCR intensity, is less in the minimum epochs than in the maximum epochs of solar activity. A vicinity of the corotating interaction regions of larger size involves in modulation higher rigidity particles of GCR than the vicinity of smaller size; thus, this statement can be considered as one of the reasons leading to the hardening of the rigidity spectrum of the harmonics of the 27-day variation of the GCR intensity in maximum epochs compared with minimum epochs of solar activity.We also show that the temporal changes of the power rigidity spectrum of the third harmonic of the 27-day variation of the GCR intensity are negatively correlated with the rigidity spectrum of the 11-year variation of the galactic cosmic ray intensity.We found a recurrence in the temporal changes of the amplitudes of the first harmonic of the 27-day variation of the GCR intensity and in some parameters of solar activity and solar wind.     

Long-term changes in copepods assemblages in the area of the Danube floodplain (Slovak–Hungarian stretch)

The present study investigates the relationship between hydrological connectivity and species diversity in a by-passed channel section, and in the adjacent water bodies of the Slovak–Hungarian Danube section (1,840.5–1,804.4 rkm). The study was designed to assess long-term temporal trends (from 1991 to 2013) in freshwater copepods assemblages and their ecological indices in different habitats of the Danube floodplain area. One of the purpose of this study was to monitor the species composition of copepods communities and ascertain their shift in various biotopes of the Danube floodplain system. Based on 23 years data, in the first step, the copepods habitat preferences using habitat values (HV) and indicator weights (IW), calculated from data collected over all the years of monitoring of planktonic communities of the Danube floodplain, were quantified. Subsequently, the floodplain index (FI) from a summary of the habitat values and indication weights of the current species was calculated, to evaluate changes in the connectivity of the anabranched section of the Slovak–Hungarian Danube. This confirmed the loss of active hydrological connectivity within the main river channel, ranging from the eupotamal to more or less isolated floodplain water bodies. Out of 50 recorded copepods species, 11 species manifest a preference for eupotamal habitats, 18 taxa preferred eupotamal B/parapotamal habitats and 21 species were found to prefer the plesiopotamal habitat type. The statistical analyses demonstrated that the structure of planktonic copepod communities in this area has changed since the Gabčíkovo hydropower plant was placed into operations. The NMDS analysis revealed shifts in the proportion of euplanktonic and tychoplanktonic species. Reversible community changes were found in the old river bed and in the eupotamal-B side arms.     

Long-term zooplankton dynamics in the Rybinsk Reservoir (1956–2005)

Materials of half-century observations of zooplankton in the Rybinsk Reservoir were used to establish reversible variations in its structure, abundance, and biomass and irreversible variations in the characteristics (trends). Variations with periods of ∼10 and 20 years have the largest effect on the community dynamics. Regression models are presented describing the dependence of zooplankton biomass averaged over May–October on its values in summer months and on the concentrations of chlorophyll a and phytoplankton and hydrothermal characteristics of the water body. Changes in zooplankton community under the effect of eutrophication and de-eutrophication of reservoir ecosystem are discussed.     

Frequency variation in site response as observed from strong motion data of the L��Aquila (2009) seismic sequence

Previous works based mainly on strong-motion recordings of large Japanese earthquakes showed that site amplification and soil fundamental frequency could vary over long and short time scales. These phenomena were attributed to non-linear soil behaviour: the starting fundamental frequency and amplification were both instantaneously decreasing and then recovering for a time varying from few seconds to several months. The recent April 6, 2009 earthquake (M _W 6.3), occurred in the L’Aquila district (central Italy), gave us the possibility to test hypotheses on time variation of amplification function and soil fundamental frequency, thanks to the recordings provided by a pre-existing strong-motion array and by a large number of temporary stations. We investigated the intra- and inter-event soil frequency variations through different spectral analyses, including time-frequency spectral ratios and S-Transform (Stockwell et al. in IEEE Trans Signal Process 44:998–1001, 1996). Finally, analyses on noise recordings were performed, in order to study the soil behaviour in linear conditions. The results provided puzzling evidences. Concerning the long time scale, little variation was observed at the permanent stations of the Aterno Valley array. As for the short time-scale variation, the evidence was often contrasting, with some station showing a time-varying behavior, while others did not change their frequency with respect to the one evaluated from noise measurements. Even when a time-varying fundamental frequency was observed, it was difficult to attribute it to a classical, softening non-linear behaviour. Even for the strongest recorded shocks, with peak ground acceleration reaching 0.7 g, variations in frequency and amplitude seems not relevant from building design standpoint. The only exception seems to be the site named AQV, where the analyses evidence a fundamental frequency of the soil shifting from 3 Hz to about 1.5 Hz during the mainshock.     

Low-frequency current variability observed at the shelfbreak in the northeastern Gulf of Mexico: November 2004–May 2005

Fourteen acoustic Doppler current profilers (ADCPs) were deployed on the shelf and slope for 1 year just west of the DeSoto Canyon in the Northeastern Gulf of Mexico by the Naval Research Laboratory (NRL) as part of its Slope to Shelf Energetics and Exchange Dynamics (SEED) project. The winter and spring observations are discussed here in regards to the low-frequency current variability and its relation to wind and eddy forcing. Empirical orthogonal function (EOF) analyses showed that two modes described most of the current variability. Wind-forced variability of the along-shelf flow was the main contributor in Mode 1 while eddies contributed much of the variability in Mode 2. Wind-stress controlled currents on the shelf and slope at time scales of about a week. On longer time scales, variations in the currents on both the outer shelf and slope appear to be related to seasonal variations in the time-cumulated wind stress curl. Winds were dominant in driving the along-shelf transports, particularly along the slope. However, the effective wind stress component was found to be aligned with the west Florida shelf direction rather than the local shelf direction. Eddy intrusions, which were more numerous in winter and spring than in summer and fall, and winds were found to contribute significantly to cross-shelf exchange processes.     

Molecular oxygen concentration at altitudes of 90–120 km according to the CORONAS-F solar UV measurements

The molecular oxygen concentration at altitudes of 90–120 km has been estimated, using the CORONAS-F/VUSS-L data on the extreme UV absorption in the Earth’s atmosphere. It has been indicated that the concentration at these altitudes is a factor of 1.3 as high as the concentration according to the Jacchia-77 model. It has been revealed that the level of solar activity slightly affects the molecular oxygen concentration at these altitudes.     

Studying the depth-dependent variation of site magnification factor in Dongchuan by earthquakes observed in borehole

IntroductionMany seismologists both at home and abroad have recognized the importance of site effect on structures of damaging earthquakes. Lots of great earthquakes occurred in China and foreign countries clearly indicate that the site response of buildings located in the seismic area has huge impact on the damage of building(s structure (JIANG, et al, 1997). The digitization of seismometer and development of computer have laid foundation of substance for quantitatively studying spatial var…     

Seasonal variation of meteor decay times observed at King Sejong Station (62.22°S, 58.78°W), Antarctica

We analyzed meteor decay times measured by a VHF radar at King Sejong Station by classifying strong and weak meteors according to their estimated electron line densities. The height profiles of monthly averaged decay times show a peak whose altitude varies with season at altitudes of 80?85 km. The higher peak during summer is consistent with colder temperatures that cause faster chemical reactions of electron removal. By adopting temperature dependent empirical recombination rates from rocket experiments and meteor electron densities of 2×10⁵?2×10⁶ cm^?3 in a decay time model, we are able to account for decreasing decay times below the peak for all seasons without invoking meteor electron removal by hypothetical icy particles.     

Intensity of Pc5 geomagnetic pulsations observed on the Earth’s surface, depending on the corresponding oscillation mode (poloidal or toroidal) in the magnetosphere

Thirty-six cases of Pc5 geomagnetic pulsations on the GOES-8 geostationary satellite for 2001, which had amplitudes equal to several nanoteslas and continued for more than an hour, have been studied. Twenty-two and 14 pulsations were toroidal and poloidal, respectively. All these pulsations were compared with geomagnetic observations at the Poste-de-la-Baleine observatory (PBQ), which was located near the satellite projection. It was established that the pulsation frequencies on the ground and in the magnetosphere do not always coincide. It has been detected that poloidal oscillations have small and large amplitudes on the ground and in the magnetosphere, respectively; the situation is opposite for toroidal oscillations. The amplitude of ground-level pulsations to a larger degree depends on the azimuthal field component in the magnetosphere than on the radial component.     

Watershed systems science—A new paradigm to understand and govern the impact of human activities on the earth's surface in the Anthropocene

正Recent scholars’work in Vol 58 Issue 1(2015)and Cheng and Li’s paper in Vol 58 Issue 7(2015)in Science China Earth Sciences propose development of"Watershed science"by"Bridging new advances in hydrological science with good management of river basins".An analysis of the language and key concepts used in the abstracts,titles and keywords of this set of 8 papers and an editorial reveals that‘Watershed’,‘River’,‘Science’and‘System’are the main     

Auroras observed in the Iberian Peninsula (1700–1855) from Rico Sinobas’ catalogue

A catalogue of auroras was compiled by the Spanish physicist Rico Sinobas in 1855. It presents the auroras observed in the Iberian Peninsula in the period 1700–1855, and is of special interest because observations were at low-latitude sites. We analyse the reliability of the data, and find that this compilation confirms for low latitudes the absence of auroras during the Dalton minimum.     

Multi-dipole observation system and study on the abnormal variation of the geoelectric field observed at Capital Circle area before the Wen’an MS5.1 earthquake

On July 4,2006,a MS5.1 earthquake occurred in Wen’an county of Hebei Province of which the epicenter is near the Beijing city.The six geoelectric field monitoring stations have been in operation for several years around the Beijing area to examine the relationship between electric field changes and earthquake.This paper firstly explains the principle of the eliminating noise method by using multi-dipole observation system of the geoelectric field.Then the data observed at the stations are studied and a lot of abnormal signals preceding the Wen’an earthquake are selected,of which five abnormal signals of the geoelectric field are finally recognized as the precursory signals.The result shows that 1 there probably exists the precursory signals of the geoelectric field preceding the Wen’an earthquake;2 there are sensitive sites in the spatial distribution of the abnormal variation of the geoelectric field before the quack;3 the anomalous signals do not appear synchronously,and their durations are not same at dif-ferent stations;4 the amplitudes of the abnormal signals recorded at Baodi station are small,but large at Changli station,while the latter is farther from the epicentral area than the former.