Background component of methane concentration in surface air (Obninsk monitoring station)

We present measurement data from February 1998 to January 2014 obtained by Fourier spectroscopy for bulk methane concentrations in surface air samples. We have excluded the results of individual measurements of high methane concentrations arising at a temperature inversion and during fires to separate the monthly mean concentrations into the regional natural background concentration of methane and its anthropogenic addition. A seasonal concentration has been separated from the background concentration. Spectral analysis reveals a large number of composite oscillations of variations in the background methane concentra- tion with periods of 3 to 126 months. A model with the use of empirical parameters of these oscillations describes the temporal changes in the methane concentration with an error of less than 3%. The anthropogenic addition of CH₄ in the atmosphere is largely of a random character. Over 16 years of observations, its increase was ~23.7 ppb, which has resulted in an increase in the total CH₄ concentration by the same amount.     

Comparative morphological analysis of the diurnal rhythms in geomagnetic and seismic activity

To verify the hypothesis of the possible influence of geomagnetic variations on seismicity, the structures of the diurnal rhythms of seismicity in Garm research area, Tajikistan, and geomagnetic activity are investigated in detail using the regional index of geomagnetic activity at the Tashkent Astronomical Observatory. We compare (1) the average shape of the diurnal variations and its seasonal changes; (2) temporal changes in special coefficients of the amplitude variations and the diurnal variation stability. It is revealed that the dynamics of the mentioned parameters differ considerably between the geomagnetic and seismic activities. We conclude that the results obtained on the basis of the used data and processing techniques do not confirm the hypothesis of possible influence of weak geomagnetic variations on background seismicity in the Garm region, Tajikistan.     

Analysis of optimal conditions for recording signals when studying the atmospheric boundary layer with the acoustic method of partial reflection

Equations for the coefficient of partial reflection K from stratified inhomogeneities in the atmospheric boundary layer have been derived on the basis of the Epstein transition and symmetrical layer models as functions of three dimensionless parameters, i.e., the relative layer altitude, its relative thickness, and the relative variations in the effective sound speed in a layer. The equations have been obtained for the relative layer altitude at which the total internal reflection appears; the behavior of the function K is studied at close altitudes. Significant weakening of the dependence of coefficient K on the relative layer thickness in these conditions is shown, which makes it possible to record partially reflected signals in a wide range of wave-lengths or frequencies of the sounding signal. In other cases, the coefficient of partial reflection K strongly depends on the layer thickness. According to experimental data on variations in the amplitude of received acoustic signals with an increase in the source-detector distance, a technique for the parameterization of the additional impedance attenuation of sound that propagates over the earth’s surface has been developed, and these parameters have been experimentally estimated for different stratification conditions and sounding signal frequencies. Many records of background acoustic noises typical for one or another measurement sites have been distinguished and classified, a technique for estimating the minimum signal amplitude distinguishable against noises has been developed, and the corresponding estimates have been made. Based on these data and the specifications of three different industrial acoustic sources, the parameter limits provided by these sources have been estimated for the method of partial reflection.     

Three-dimensional refined modeling of water quality in Victoria Harbour

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Entropy analysis of in situ particle size spectra

Entropy analysis has been used to classify in situ particle (floc) size spectra of suspended particles into groups based on similar distribution characteristics. Results revealed that the in situ spectra sorted into groups that reflected different forcing conditions (e.g. variations in turbulence). The different forcing conditions were not necessarily reflected in other commonly used distribution measures such as median floc diameter. This suggests that entropy analysis may be an effective approach for investigating the effect of changes in forcing conditions on floc size. It is hypothesized that it may be possible to derive the average shape of floc size spectra from measurement of the forcing conditions alone and subsequently derive parameters such as floc fraction, floc density, floc settling velocity and the optical properties of the water column from the average spectra.     

A three-dimensional numerical model of hydrodynamics and water quality in Hakata Bay

The hydrodynamics and water quality in Hakata Bay, Japan, are strongly affected by the seasonal variations in both the gravitational circulation and the stratification in the bay. The three-dimensional hydrodynamics and water quality model has been developed to simulate the long-term transport and fate of pollutants in the system. The model is unique in that it completely integrates the refined modelling of the hydrodynamics, biochemical reactions and the ecosystem in the coastal areas. It is a 3-dimensional segmented model which is capable of resolving mean daily variations in all the parameters relevant to pollution control. It predicts daily fluctuations in the oxygen content at different depths in water throughout the year. It takes into account transport and settling of pollutant particles. It predicts light penetration from computed turbidity variations. It includes interactions between the ecosystem and water quality, through nutrient cycling and photosynthesis. The model has been calibrated well against the data set of historical water quality observations in Hakata Bay.     

Extremely low magnetic fields as a factor of modulation and synchronization of infradian biorhythms in animals

The studies of the influence that a magnetic field (MF) with a frequency of 8 Hz has on the infradian rhythms of physiological and metabolic processes indexes in animals have been carried out in order to verify the hypothesis on the synchronizing effect of natural electromagnetic fields. It is shown that the MF effect has alternating characteristics of the time organization of energetic physiological and metabolic processes in animal organisms in an infradian range and the partial smoothing of biorhythmic deviations between individual-typological groups of organisms occurs for single processes. This (i) shows the common system reaction mechanisms that the organisms of animals have to the effect of a certain factor and (ii) is evidence of the synchronizing influence of the daily influence of magnetic fields of extremely low frequencies on populations of organisms with initially different biorhythmic types. It has been concluded that the stable variations of electromagnetic background, including natural, can serve as a timer for biorhythms in a wide range of periods.     

Comparative analysis of land,marine, and satellite observations of methane in the lower Atmosphere in the Russian Arctic under conditions of climate change

Land, marine, and satellite observations have been used to study changes in methane concentrations in the lower atmosphere during the warm months of the year (July through October) in Arctic regions having different potentials for methane production. The Atmospheric Infrared Sounder (AIRS) data for 2002–2013 are used to explore the interplay between local methane sources in the terrestrial region of the Eurasian Arctic and on the Arctic shelf over the warm period of the year. Linear trends in atmospheric methane concentrations over different Arctic regions are calculated, and a hypothesis of the relation of concentration variations to climatic parameters is tested. The combination of land, marine, and satellite observation is used to develop a conceptual model of the atmospheric methane field in the terrestrial part of the Russian Arctic and on the Arctic shelf. It is shown that the modern methane growth rate in the Arctic does not exceed the Northern Hemisphere mean. It is concluded that the methane emission in the Arctic has little effect on global climate compared to other factors.     

东菲律宾海柱样沉积物的磁性特征

对东菲律宾海帕里西维拉海盆西侧F090102柱样进行了系统的古地磁和岩石磁学研究,测量了天然剩磁倾角、磁化率、饱和等温剩磁、非磁滞剩磁、-T曲线等磁学参数,进行了磁性地层的划分对比,识别出松山反极性时内的贾拉米洛和奥都维正极性亚时。对磁学参数及其有关比值的研究发现,岩心磁性矿物以低矫顽力磁铁矿为主,可能含有一定的钛磁铁矿。磁性矿物主要是陆源碎屑成因,岩心底段受到海底火山作用的影响。根据磁学参数随深度的变化将岩心分为3段,各段反映了沉积环境和古气候的变化。     

Characteristics of manganese micronodules as indicators of sedimentation conditions in pelagic sediments

Pelagic sediments from three cores in the northern tropical Pacific zone (the northeast basin) have been analyzed for particle size and composition, as well as for number, mass and the distribution of protosyngenetic authigenic manganese micronodules (MN) in them. The sequences are represented by Quaternary carbonate-free clayey–radiolarian, radiolarian–clayey oozes, miopelagic clays, sometimes enriched in radiolarians, pre-Pleistocene miopelagic and eupelagic clays, zeolite–clayey sediments, and zeolitites. Based on factual data (volume of wet sediment, weight of dry sediment and micronodules, their number and proportions of four fractions, the contribution of MN in sediment, and others), the values of different parameters were calculated. The obtained parameters are statistically similar, which allowed us to reveal background and anomalous horizons of sediments and to assume their sedimentation conditions. Similar values of Р_MN/N_MN, Р_fr > 0.05 mm, Р_MN/Р_sed and the mass of micronodules suggest that precisely these parameters reflect the main variations in conditions of pelagic sedimentation.     

The impact of natural mortality variations on the performance of management procedures for Spanish mackerel(Scomberomorus niphonius) in the Yellow Sea,China

Natural mortality rate(M) is one of the essential parameters in fishery stock assessment, however, the estimation of M is commonly rough and the changes of M due to natural and anthropogenic impacts have long been ignored.The simplification of M estimation and the influence of M variations on the assessment and management of fisheries stocks have been less well understood. This study evaluated the impacts of the changes in natural mortality of Spanish mackerel(Scomberomorus niphonius) on their management strategies with data-limited methods. We tested the performances of a variety of management procedures(MPs) with the variations of M in mackerel stock using diverse estimation methods. The results of management strategies evaluation showed that four management procedures DCAC, SPMSY, cur E75 and minlen Lopt1 were more robust to the changes of M than others; however, their performance were substantially influenced by the significant decrease of M from the 1970s to 2017. Relative population biomass(measure as the probability of B0.5 BMSY) increased significantly with the decrease of M, whereas the possibility of overfishing showed remarkable variations across MPs. The decrease of M had minor effects on the long-term yield of cur E75 and minlen Lopt1, and reduced the fluctuation of yield(measure as the probability of AAVY15%) for DCAC, SPMSY. In general, the different methods for M estimation showed minor effects on the performance of MPs, whereas the temporal changes of M showed substantial influences. Considering the fishery status of Spanish mackerel in China, we recommended that cur E75 has the best trade-off between fishery resources exploitation and conservation, and we also proposed the potentials and issues in their implementations.     

Effect of solar activity and geophysical disturbance on physical-chemical processes in liquid medium: Preliminary analysis of storm-glass activity

Changes in the state of a solution in storm glasses (Fitzroy retort) have been recorded by measuring the height of the level of crystals. Devices manufactured by a group of Crimean researchers have been used to measure these characteristics daily since 1995. Fragments of an accumulated observation dataset have been processed employing standard meteorological and cosmophysical indices. It is found that, 2–3 days before isolated sharp drops in the atmospheric pressure, crystal formation intensifies synchronously in two devices. A relationship is found between the activity under study and changes in the A _p geomagnetic-disturbance index and the flare-intensity index. There is a set of quasi-stable periods in variations of the activity of storm glasses, of which the 120-, 185-, and 360-day periods are most significant. The obtained results are generally consistent with views that changes in the background electromagnetic low-frequency fields are a physical agent influencing the process of crystal formation.     

Effect of Salinity and Currents on Sea Level Variation Along the Indian Coast: A Numerical Study

The process of upwelling/sinking and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. Further,precipitation and monsoonal floods, apart from the marine meteorological parameters, are expected to influence the sea level fluctuations along the coast. This study comprises determining the sea level from the various parameters together with the pure wind stress forcing, which is compared with the observed cycle. However, it is found that there is considerable difference between the computations and observations. This suggests that the sea level is dependent not just on the local forcing alone, but also on the induced background circulation as well. For example, the sea level changes along the east coast of India, particularly the northern region, are more sensitive to freshwater discharge from various rivers joining the Bay of Bengal. This is due to more frequently occurring pre- and postmonsoon cyclonic storms and the associated surges in the Bay of Bengal as compared to the Arabian Sea. Hence the salinity effects are particularly important in the coastal waters off the east coast of India during monsoon months (June-September). For the west coast of India, however, it is expected that the large-scale coastal circulation may play a role in determining sea level changes in addition to other forcings. The salinity effects are negligible along the west coast in the absence of any major river systems that join the Arabian Sea. The local advection currents caused by the offshore directed freshwater discharge from various estuaries joining the coastal bay also seemed to influence the sea level. In order to elucidate the essential dynamics involved and to study the effect of the remote forcing, a three-dimensional baroclinic, nonlinear numerical model is used with appropriate open boundary conditions. The local effect of the current has been incorporated in the west coast model by means of opening a channel at Cochin through which the rainwater is carried away to the model ocean. The low saline plume, cascading from north along the east cost of India, has been incorporated in the east coast model through a proper forcing applied at the northern boundary of the model. With the inclusion of these remote forcings in the models, the disagreement between the simulations and the observations is minimized.     

Effect of Salinity and Currents on Sea Level Variation Along the Indian Coast: A Numerical Study

The process of upwelling/sinking and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. Further,precipitation and monsoonal floods, apart from the marine meteorological parameters, are expected to influence the sea level fluctuations along the coast. This study comprises determining the sea level from the various parameters together with the pure wind stress forcing, which is compared with the observed cycle. However, it is found that there is considerable difference between the computations and observations. This suggests that the sea level is dependent not just on the local forcing alone, but also on the induced background circulation as well. For example, the sea level changes along the east coast of India, particularly the northern region, are more sensitive to freshwater discharge from various rivers joining the Bay of Bengal. This is due to more frequently occurring pre- and postmonsoon cyclonic storms and the associated surges in the Bay of Bengal as compared to the Arabian Sea. Hence the salinity effects are particularly important in the coastal waters off the east coast of India during monsoon months (June-September). For the west coast of India, however, it is expected that the large-scale coastal circulation may play a role in determining sea level changes in addition to other forcings. The salinity effects are negligible along the west coast in the absence of any major river systems that join the Arabian Sea. The local advection currents caused by the offshore directed freshwater discharge from various estuaries joining the coastal bay also seemed to influence the sea level. In order to elucidate the essential dynamics involved and to study the effect of the remote forcing, a three-dimensional baroclinic, nonlinear numerical model is used with appropriate open boundary conditions. The local effect of the current has been incorporated in the west coast model by means of opening a channel at Cochin through which the rainwater is carried away to the model ocean. The low saline plume, cascading from north along the east cost of India, has been incorporated in the east coast model through a proper forcing applied at the northern boundary of the model. With the inclusion of these remote forcings in the models, the disagreement between the simulations and the observations is minimized.     

Temporal variability of the vertical thermal structure in the vicinity of South Crimea

On the basis of the experimental investigations conducted from an oceanographic tower, the variability of the structure of temperature profiles has been analysed. The paper provides a classification of the basis types of temperature profiles and determines their frequencies and duration in the annual cycle. Dynamics of the transition from one type of a temperature profile to another has been found to have synoptic scales. The variability of parameters during an occurrence of some typical profile have been assessed; it has been deduced that variations in profile shape are linked with fine structure effects of internal waves. Translated by Vladimir A. Puchkin.     

An experimental study on the reshaping of berm breakwaters under irregular wave attacks

The main idea concerned with the design of berm breakwaters is to construct a less expensive structure with reshaping berm. An experimental study on the front slope stability of homogeneous berm breakwaters has been carried out in a large number of 2D model tests at Tarbiat Modares University. In this paper, the results of this experimental study are presented conjointly with a formula for estimation of berm recession as the most important parameter for describing the reshaping. This includes the influence of wave height and period, storm duration, berm width and elevation variations on the stability of berm breakwater with different armor stone sizes. A total of 222 tests have been performed to cover the impact of these parameters. According to the present research, one can observe that considering different armor stone sizes, berm width is a significant parameter concerning reshaping of a berm breakwater that has not been covered in previous works, so that as the berm width increases the amount of berm recession decreases. To assess the validity of the present formula, comparisons are made between the estimated berm recessions by this formula and formulae given by other researchers, showing that the estimation procedure foretells berm recession well according to the present data. It is observed that the recession estimated by the present formula has comparatively better correlation with the present experimental data, and also with other experimental results within the range of parameters tested.     

Shielding in biology and biophysics: Methodology,dosimetry, interpretation

An interdisciplinary review of the publications on the shielding of organisms by different materials is presented. The authors show that some discrepancies between the results of different researchers might be attributed to methodological reasons, including purely biological (neglect of rhythms) and technical (specific features of the design or material of the screen) ones. In some cases, an important factor is the instability of control indices due to the variations in space weather. According to the modern concept of biological exposure to microdoses, any isolation of a biological object by any material necessarily leads to several simultaneous changes in environmental parameters, and this undermines the principle of “all other conditions being equal” in the classical differential scheme of an experiment. The shielding effects of water solution are universally recognized and their influence is to be observed for all organisms. Data on the exposure of living organisms to weak combined magnetic fields and on the influence of space weather enabled the development of theoretical models generally explaining the effect of shielding for bioorganisms. Ferromagnetic shielding results in changes of both the static magnetic field and the field of radio waves within the area protected by the screen. When screens are nonmagnetic, changes are due to the isolation from the radio waves. In both cases, some contribution to the fluctuations of measured parameters can be made by variations in the level of ionizing radiation.     

Formula for a baroclinic adjustment theory of climate

Recently, a theory relating baroclinic neutrality and midlatitudes tropopause height has been proposed. However, GCM results have shown that the dependence of the theory on external parameters is not consistent with that displayed by these numerical experiments. In the present paper we suggest an analytic formula for baroclinic adjustment to the neutrality of Eady waves through tropopause modification. This formula extends considerably the abovementioned theory by taking into account both a simple representation of the stratosphere and the topography. These modifications alter the tropopause condition for a baroclinically neutral state and its sensitivity to the external parameters. In particular, the topography introduces a dependence on the tropospheric vertical wind shear of the neutrality condition. This feature is not present in other models that assume a background state with a zero potential vorticity gradient in the troposphere. We show, furthermore, that the modified neutrality condition has sensitivities that may resemble those displayed by GCM simulations, with respect to the parameters defining the background flow.     

Height-latitude structure of the vertical component of the migrating semidiurnal tide in the upper mesosphere and lower thermosphere region (80–100 km)

The height-latitude distributions of parameters of the vertical wind component of the semidiurnal tide were calculated for the mesosphere and lower thermosphere (MLT) region (80–100 km) on the basis of empirical height-latitude distributions of the monthly mean parameters of variations in the horizontal wind component of the migrating semidiurnal tide. The constructed distributions are compared with the results of a numerical modeling of the migrating semidiurnal tide with the aid of a model of global circulation in the middle and upper atmosphere, as well as with the parameters of semidiurnal temperature variations obtained from the data of satellite measurements. It is shown that different models yield the distributions of parameters of semidiurnal variations, which agree within the errors of their values. The presence of high-latitude regions of local maximal amplitudes is a specific feature of the distributions of parameters of semidiurnal variations in the vertical wind constructed in the course of this work. On the whole, at heights of about 90 km and higher, semidiurnal variations in the vertical wind exceed the prevailing vertical wind in amplitude.