High <Emphasis Type="Italic">S</Emphasis>-wave attenuation anomalies and ringlike seismogenic structures in the lithosphere beneath Altai: Possible precursors of large earthquakes

This paper addresses inhomogeneities in the short-period S-wave attenuation field in the lithosphere beneath Altai. A technique based on the analysis of the amplitude ratios of Sn and Pn waves is used. High S-wave attenuation areas are identified in the West Altai, which are related to the source zones of recent large earthquakes, viz., the 1990 Zaisan earthquake and the 2003 Chuya earthquake. Associated with the Chuya earthquake, a large ringlike seismogenic structure had been formed since 1976. It is also found that ringlike seismogenic structures are confined to high S-wave attenuation areas unrelated to large historical earthquakes. It is supposed that processes paving the way for strong earthquakes are taking place in these areas. The magnitudes of probable earthquakes are estimated using the earlier derived correlation dependences of the sizes of ringlike seismogenic structures and the threshold values of magnitudes on the energy of principal earthquakes with prevailing focal mechanisms taken into consideration. The sources of some earthquakes are likely to occur near to the planned gas pipeline route from Western Siberia to China, which should be taken into account. The relationship of anomalies in the S-wave attenuation field and the ringlike seismogenic structures to a high content of deep-seated fluids in the lithosphere is discussed.     

Measuring chlorophyll <Emphasis Type="Italic">a</Emphasis> concentrations in the Sea of Japan using probe and flow fluorimeters

The spatial variability of chlorophyll a concentrations was studied from the data of two near-shore expeditions and the cruise of the R/V Akademik M.A. Lavrent’ev in October–November 2010 over the northwestern part of the Sea of Japan. The sections across eddies showed a maximum of chlorophyll a at a depth of 40 m. According to the data from the cruise, the chlorophyll a concentration was maximum in the north of the sea and decreased to the south. In parallel, the procedures for chlorophyll a determination were compared for spectrophotometry with a fluorescence probe and a fluorescence flow system. The probe data of chlorophyll a fluorescence showed a high correlation with the chlorophyll a concentrations by spectrophotometry. On the contrary, data on chlorophyll a concentrations from spectrophotometry did not agree with those from the flow system. It was shown that a fluorimeter in the flow system recorded dissolved organic matter along with the chlorophyll a fluorescence.     

Variability of Particulate Organic Phosphorus in the Northwestern Part of the Black Sea

Based on long-term (1985–1995) monitoring data, the paper considers the peculiarities of seasonal variability in the spatial and vertical distribution of particulate organic phosphorus (Р_POM) in the surface layer and in the photosynthetic zone in the northwestern Black Sea. Regression equations, experimental data, and satellite observations for the chlorophyll a concentration allowed us to evaluate the seasonal longterm (1979–1995) variability in Р_POM in the surface layer and photosynthesis zone. The ratios of the concentrations of particulate organic carbon, nitrogen, phosphorus, and chlorophyll a are calculated and statistical estimates of seasonal changes in the Р_POM in the areas with different degrees of influence of river runoff and water of open seas are obtained. The consistency of intra-annual changes in the concentrations of Р_POM, chlorophyll a, and phytoplankton biomass is shown, which indicates the role of phytoplankton in the formation of Р_POM and in its intra- and interannual variability in the northwestern part of the sea. It is shown that long-term seasonal variations in Р_POM and related changes in the concentration of chlorophyll a depend on the variability of bulk river runoff, the extent of its abundance in the northwestern shelf, and regional hydrometeorological conditions.     

南极西北威德尔海上层海洋湍流混合研究

Turbulent mixing in the upper ocean(30-200 m) of the northwestern Weddell Sea is investigated based on profiles of temperature,salinity and microstructure data obtained during February 2014.Vertical thermohaline structures are distinct due to geographic features and sea ice distribution,resulting in that turbulent dissipation rates(ε) and turbulent diffusivity(K) are vertically and spatially non-uniform.On the shelf north of Antarctic Peninsula and Philip Ridge,with a relatively homogeneous vertical structure of temperature and salinity through the entire water column in the upper 200 m,both ε and K show significantly enhanced values in the order of O(10~(-7))-O(10~(-6)) W/kg and O(10~(-3))-O(10~(-2)) m~2/s respectively,about two or three orders of magnitude higher than those in the open ocean.Mixing intensities tend to be mild due to strong stratification in the Powell Basin and South Orkney Plateau,where s decreases with depth from O(10~(-8)) to O(10~(-9)) W/kg,while K changes vertically in an inverse direction relative to s from O(10~(-6)) to O(10~(-5)) m~2/s.In the marginal ice zone,K is vertically stable with the order of10~(-4) m~2/s although both intense dissipation and strong stratification occur at depth of 50-100 m below a cold freshened mixed layer.Though previous studies indentify wind work and tides as the primary energy sources for turbulent mixing in coastal regions,our results indicate weak relationship between K and wind stress or tidal kinetic energy.Instead,intensified mixing occurs with large bottom roughness,demonstrating that only when internal waves generated by wind and tide impinge on steep topography can the energy dissipate to support mixing.In addition,geostrophic current flowing out of the Weddell Sea through the gap west of Philip Passage is another energy source contributing to the local intense mixing.     

Simulating the Propagation of Infrasonic Waves and Estimating the Energy of the Chelyabinsk Meteoroid Explosion Observed on February 15, 2013

Results obtained from simulating the propagation of infrasonic waves from the Chelyabinsk meteoroid explosion observed on February 15, 2013, are given. The pseudodifferential parabolic equation (PDPE) method has been used for calculations. Data on infrasonic waves recorded at the IS31 station (Aktyubinsk, Kazakhstan), located 542.7 km from the likely location of the explosion, have been analyzed. Six infrasonic arrivals (isolated clearly defined pulse signals) were recorded. It is shown that the first “fast” arrival (F) corresponds to the propagation of infrasound in a surface acoustic waveguide. The rest of the arrivals (T1–T5) are thermospheric. The agreement between the results of calculations based on the PDPE method and experimental data is satisfactory. The energy E of the explosion has been estimated using two methods. One of these methods is based on the law of conservation of the acoustic pulse I, which is a product of the wave profile area S/2 of the signal under analysis and the distance to its source E _I [kt] = 1.38 × 10^–10 (I [kg/s])^1.482. The other method is based on the relation between the energy of explosion and the dominant period T of recorded signal E _T [kt] = 1.02 × (T [s]²/σ)^3/2, where σ is the dimensionless distance determining the degree of nonlinear effects during the propagation of sound along ray trajectories. According to the data, the explosion energy E _I,T ranges from 1.87 to 32 kt TNT.     

Estimating the parameters of pulsed sources from data on acoustic waves recorded in the atmosphere

The possibility of estimating the parameters of surface pulsed sources from data on acoustic waves recorded in the atmosphere is studied. Experimental values are given for peak pressure P ₊ of recorded acoustic signals, wave-profile area S ₊ in their positive phase, and length t ₊ of this phase, and the approximations of these parameters are obtained within wide ranges of source energy 10^–3 < E < 10¹⁰ kg TNT and scaled distances 1 < R/E ^1/3 < 4 × 10⁴ m/kg^1/3. Conventional methods of estimating the acoustic energy E according to data obtained from acoustic measurements in the atmosphere are analyzed, and ways to improve their accuracy are proposed. The influence of the type of explosions on the parameters P ₊, S ₊, and t ₊ of acoustic signals at long distances R/E ^1/3 > 500 m/kg^1/3 from explosions is shown.     

Spatial Distribution and Seasonal Dynamics of the Chlorophyll <Emphasis Type="Italic">a</Emphasis> Concentration in the Sea of Azov Based on MERIS Images

The chlorophyll a concentration (Cchl a) in the Sea of Azov is estimated by the two-band NIR-red algorithm [34] from MERIS images for 2002–2012. The sea-truth spectrophotometric measurements and MERIS remote estimates of Cchl a are compared. The monthly average Cchl a values are mapped from MERIS data for its lifetime for the first time. The features of the spatiotemporal distribution of Cchl a are ascertained. Differences between the seasonal dynamics of Cchl a in the Sea of Azov according to the literature data and the dynamics derived from MERIS data are found, namely: the summer–autumn phytoplankton growth period is longer than the spring period and is characterized by higher Cchl a values throughout the water area.     

Morphological characteristics and distribution of Pleuronectidae (Pisces) eggs in the western margin of the East Sea

Seven species of Pleuronectidae (Platichthys stellatus, Kareius bicoloratus, Pseudopleuronectes herzensteini, Microstomus achne, Glyptocephalus stelleri, Hippoglossoides dubius, and Limanda punctatissima) were identified based on eggs collected from the western margin of the East Sea (east coast of Korea), using DNA barcoding. The eggs of P. herzensteini and G. stelleri were relatively widely distributed along the east coast of Korea, whereas those of P. stellatus and K. bicoloratus were narrowly distributed; in particular, the eggs of P. stellatus were restricted to areas near bays. The eggs, which share common morphological characteristics (such as a homogeneous yolk and smooth membrane) were divided into three groups according to egg size: group A (more than 1.60 mm in egg diameter, including genera Hippoglossoides and Microstomus), group B (1.00–1.60 mm, including genera Kareius, Glyptocephalus, and Platichthys), and group C (less than 1.00 mm, including genera Limanda and Pseudopleuronectes). This paper provides an overview of the morphological characteristics of the eggs of the family Pleuronectidae collected from the east coast of Korea. Our approach to the analysis of eggs, based on DNA barcoding, morphological characteristics, and geographic distributions, provides a rapid and accurate basis for identifying spawning areas and spawning periods, thus facilitating the assessment and management of fisheries stocks and resources.     

Vertical turbulent exchange in the Black Sea pycnocline and its relation to water dynamics

Estimates of vertical turbulent diffusion coefficient (K _t ) in the Black Sea pycnohalocline have been obtained from data of simultaneous observations of seawater temperature, salinity, density, and horizontal current velocity, obtained in the northeastern part of the Black Sea during 2013–2014 with a moored Aqualog profiler. A Munk and Andersson (1948) type parameterization, adapted for the Black Sea environment, is proposed for calculating K _t . Strong short-period (several days) variability of turbulent exchange is revealed, induced by vertical shear variations of the current velocity.     

Molecular phylogeny of the genus <Emphasis Type="Italic">Chondracanthus</Emphasis> (Rhodophyta), focusing on the resurrection of <Emphasis Type="Italic">C. okamurae</Emphasis> and the description of <Emphasis Type="Italic">C. cincinnus</Emphasis> sp. nov.

Determining the taxonomic status of the red algal genus Chondracanthus based on morphological characters is challenging due to the similarity and high degree of plasticity of the thallus. Since the taxonomic history of several Chondracanthus species remains unclear, we analyzed the plastid rbcL and mitochondrial COI genes of the specimens from Korea and Japan, in combination with morphological observations, to examine their phylogenetic relationships. Our results confirmed the distinction of C. okamurae, which is separated from C. intermedius, and identified a novel species, C. cincinnus sp. nov. Three species (C. okamurae, C. intermedius and C. cincinnus) formed a monophyletic clade with C. tenellus. C. okamurae is distinguished by linear, narrow, cylindrical to compressed, slightly recurved axes, and a high-intertidal to subtidal distribution. It was collected from Korea and Japan, while C. intermedius was identified from Japan only. A new species, Chondracanthus cincinnus sp. nov., is characterized by linear, compressed, strongly recurved axes, and a low-intertidal to subtidal distiribution. Based on the molecular phylogeny using rbcL and COI data, we herein resurrect C. okamurae as a distinct species and identify C. cincinnus as a new species.     

水下溢油油滴粒径分布实验研究

Oil droplet size distribution(ODSD) plays a critical role in the rising velocity and transport of oil droplets in subsurface oil releases. In this paper, subsurface oil release experiments were conducted to study ODSD under different experimental conditions in a laboratory water tank observed by two high-speed cameras in March and April 2017. The correlation formulas Oh=10.2 Re~(–1) and Oh=39.2 Re~(–1)(Re represents Reynolds number and Oh represents Ohnesorge number) were established to distinguish the boundaries of the three instability regimes in dimensionless space based on the experimental results. The oil droplet sizes from the experimental data showed an excellent match to the Rosin–Rammler distribution function with determination coefficients ranging from 0.86 to 1.00 for Lvda 10-1 oil. This paper also explored the influence factors on and change rules of oil droplet size. The volume median diameter d50 decreased steadily with increasing jet velocity, and a sharp decrease occurred in the laminar-breakup regime. At Weber numbers(We) 100, the orifice diameter and oil viscosity appeared to have a large influence on the mean droplet diameter. At 100We1 000, the oil viscosity appeared to have a larger influence on the relative mean droplet diameter.     

Features of the spatial distribution of phytoplankton in Nhatrang Bay of the South China Sea during the rainy season

The species composition, phytoplankton abundance, and relative yield of the variable fluorescence (F _v /F _m ) were determined in the mesotrophic Nhatrang Bay in October–November of 2004. The species diversity (250 taxonomic units) and heterogeneity of the phytoplankton structure were high. With respect to the number of species and their abundance, diatoms prevailed. In selected parts of the bay, dinoflagellates dominated. The mean biomass in the water column under 1 m² (B _t ) varied from 2.3 to 64.4 mg C/m³ being 31.0 mg C/m³ on average. The values of B _t were the lowest at the stations nearest to the river mouth. Seaward, B _t increased. The values of B _t increased with depth at some stations and decreased at others. In the surface sea layers, the biomass was lower than that in the underlying waters. The values of F _v /F _m ranged from 0.10 to 0.64 (at a mean value of 0.49). The lowest values of F _v /F _m were observed in the area close to the seaport. Over the greater part of the bay, the values of F _v /F _m were higher than 0.47. Such values are indicative of the relatively high potential photosynthetic activity of the phytoplankton. The abundance and species diversity were higher than those in the dry season (March–April).     

Wave Activity and Its Changes in the Troposphere and Stratosphere of the Northern Hemisphere in Winters of 1979–2016

An analysis of spectra of wave disturbances with zonal wave numbers 1 ≤ k ≤ 10 is carried out using winter (November to March) ERA-Interim reanalysis geopotential data in the troposphere and stratosphere for 1979–2016. Contributions of eastward-traveling (E), westward-traveling (W), and stationary (S) waves are estimated. The intensification of wave activity is observed in the tropical troposphere and stratosphere and in the upper stratosphere of the entire Northern Hemisphere. The intensification of wave activity in the tropics and subtropics is noted for waves of all types (E, W, and S), while in the middle and higher latitudes it is related mainly to stationary and eastward waves. Near the subtropical tropopause, the energy of stationary waves has increased in recent decades. In addition, in the tropical and subtropical troposphere and in the subtropical lower stratosphere, the energy of the eastward-traveling waves in El Niño years may be one and a half times or twice the energy in La Niña years. The spectrally weighted zonal wave numbers for waves of all types (E, W, and S) are the largest in the upper subtropical troposphere. The spectrally weighted zonal wave number for W and S waves is correlated with the Atlantic Multidecadal Oscillation index and varies by 15% in 1979–2016 (on an interdecadal time scale). The spectrally weighted wave period is larger in the stratosphere than in the troposphere. It is maximal in the middle extratropical stratosphere. The spectrally weighted wave periods correlate with the activity of sudden stratospheric warmings. The sign of this correlation depends on the latitude, atmospheric layer, and zonal wave number.     

Seasonal dynamics and estimation of the annual primary production of phytoplankton in the Black Sea

Seasonal variations in the surface chlorophyll a concentrations (Chl _s) and the integrated primary production (PP _inf) were investigated for ten regions of the Black Sea based on long term observations (1973–1997). Two or three maximums of both Chl _s and PP _inf were registered in most of the shelf regions (SR, <200 m), the continental slope (CS, 200–1500 m), and the deep regions (DSR >1500 m) in February–March, June–August, and October–November. Such a pattern suggests that the seasonal dynamics of PP _inf strongly depend on the Chl _s variability. The mean annual values of the PP _inf comprised 130–420, 130–150, and 140–150 g C m^?2 in the SR, CS, and DSR, respectively. These values are mainly typical of the eutrophic layer and the transition between the eutrophic and mesotrophic waters (SR) or for the upper boundary of the mesotrophic waters (CS and DSR). The maximal contribution of the wintertime (December–March) to the total PP _inf values (40–42%) was observed in the DSR. In the SR and the adjacent eastern CS areas, the proportion of the PP _inf summertime production (June–September) reaches 40–60% and is higher than the wintertime production. The lowest values of PP _inf (9–17%) were produced in the spring and autumn periods. The total annual values of PP _inf in the Black Sea are close to 50–70 Mt C.     

Effect of the nonlinear interaction of tidal harmonics on their spatial structure as applied to the system of the white and Barents Seas

Using the three-dimensional nonlinear finite-element thermohydrodynamic model QUODDY-4, we obtain two solutions giving an idea of the role of the nonlinear interaction of tidal harmonics in the formation of their spatial structure. The first solution is induced by the total tide (M ₂ + S ₂ + K ₁ + O ₁) at the open boundary and by the total static tide inside the area under consideration; then, the solution obtained is subject to harmonic analysis. The second solution is obtained by specifying such tidal sea level elevations at the open boundary that meet individual tidal harmonics. These two solutions are compared. It is shown that the differences between the solutions for the S ₂, K ₁, and O ₁ waves can be significant, especially near the open boundary between the White and Barents seas. This conclusion remains valid also for the maximum velocities (major semiaxes of the ellipses) of the barotropic (depth-average) tidal current as well as for the average (over the tidal cycle) densities of the total tidal energy and components of the tidal-energy budget. The emergence of this feature indicates that there are resonance modes with frequencies that differ from those of the S ₂, K ₁, and O ₁ harmonics to a lesser extent than the M ₂ harmonic frequency. The same conclusion can be made by comparing the values of the amplification factor, which is defined as the ratio between the actual and static tides, for the system of the Barents and White seas as a whole and for Mezen Bay in the White Sea and Czech Bay in the Barents Sea, taken separately.     

Species composition and seasonal dynamics of the population density and biomass of the genus <Emphasis Type="Italic">Pyramimonas</Emphasis> (Prasinophyceae) from the Russian waters of East/Japan Sea

The species composition and seasonal dynamics of the population density and biomass of the prasinophycean algae of the genus Pyramimonas were investigated in the Russian waters of the East/Japan Sea. According to literature data and the results of our observations, eight species of the prasinophycean algae were identified, and some of them were new for the Russian waters of the East/Japan Sea as follows: P. aff. amylifera Ñonrad, P. aff. cordata McFadden, Hill et Wetherbee, and P. nansenii Braarud. An analysis of their seasonal dynamics showed that the most conspicuous winter peak of the population density of Pyramimonas species in the Amurskii Bay was clearly distinguishable in February. In winter and early spring, the prasinophycean algae made a considerable contribution of 28 to 60% into the total population density on the background of a relatively low biomass, 1.1–14.4% of the total phytoplankton biomass in the Amurskii Bay. In the Golden Horn Bay, the summer peak of the population density of Pyramimonas species was most intensive in June. In summer, during the period of mass development of the algae of the genus Pyramimonas in the Golden Horn Bay, the prasinophycean algae contributed up to 71% of the total population density and up to 84% of the total microalgal biomass. An increase was noted in the density and biomass of the Pyramimonas species in the polluted waters near the sewage water outlets in the Amurskii and Golden Horn bays.     

Retrieval of total ozone in the mesosphere with a new model of electronic-vibrational kinetics of O<Subscript>3</Subscript> and O<Subscript>2</Subscript> photolysis products

The paper presents a new model of electronic-vibrational kinetics of the products of ozone and molecular oxygen photodissociation in the terrestrial middle atmosphere. The model includes 45 excited states of the oxygen molecules O₂(b ¹, Σ _g ⁺ ,v= 0−2), O₂ (a ¹Δ _g , v= 0−5), and O₂(X ³Σ _g ⁻ , v= 1−35) and of the metastable atom O (¹ D) and over 100 aeronomic reactions. The model takes into account the dependence of quantum yields of the production of O₂(a ¹Δ _g , v= 0−5) in a singlet channel of ozone photolysis in the Hartley band on the wavelength of photolytic emission. Taking account of the electronic-vibrational kinetics is important in retrieval of the vertical profiles of ozone concentration from measured intensities of the Atm and IR Atm emissions of the oxygen bands above 65 km and leads to an increase in the ozone concentration retrieved from the 1.27-μm emission, in contrast to the previous model of pure electronic kinetics. Sensitivity analysis of the new model is made for variations in the concentrations of atmospheric constituents ([O₂], [N₂], [O(³P)], [O₃], [CO₂]), the gas temperature, rate constants of the reactions, and quantum yields of the reaction products. A group of reactions that most strongly affect the uncertainty of ozone retrieval from measured intensities of atmospheric emissions of molecular oxygen O₂(b ¹Σ _g ⁺ , v) and O₂(a ¹Δ _g , v) has been determined. Original Russian Text ? V.A. Yankovsky, V.A. Kuleshov, R.O. Manuilova, A.O. Semenov, 2007, published in Izvestiya AN. Fizika Atmosfery i Okeana, 2007, Vol. 43, No. 4, pp. 557–569.     

Species Composition and Distribution of Sibling Species of the Genus <Emphasis Type="Italic">Chironomus</Emphasis> Meigen (Diptera: Chironomidae) in the Curonian and Vistula Lagoons,Baltic Sea

The species compositions of the genus Chironomus in the Curonian and Vistula lagoons are very similar, represented by Ch. plumosus and Ch. balatonicus. In the Curonian Lagoon, in addition to these two species, Ch. muratensis and the first-generation interspecific hybrid Ch. muratensis × Ch. plumosus are also found. In this lagoon, Ch. plumosus occurs most frequently (84%); Ch. balatonicus is considered a subdominant species (24%). In the Vistula Lagoon, on the contrary, the high frequency of occurrence is typical of Ch. balatonicus (89%); for Ch. plumosus, it reaches only 11%. The Ch. plumosus population occupies most of the Curonian Lagoon; Ch. balatonicus is present only in its northern part, from the village of Juodkrante to the city of Klaipeda. In the Vistula Lagoon, Ch. balatonicus is distributed over almost its entire area, while Ch. plumosus is found locally, only near the mouth of the Nogat River. The distribution of the sibling species in the lagoons is determined by the salinity gradient.     

Retrospective analysis of seismic regime features before the Taiwan earthquakes of 1999 and 2002

The features of the seismic regime before the strongest earthquakes of Taiwan in the late 20th (Chi-Chi on September 21, 1999, M_w = 7.6) and the early 21st century (March 31, 2002, M_w = 7.4) are analyzed. Based on 1990–1999 and 1994–2002 data, respectively, retrospective analysis of three seismic regime parameters are studied: the total annual number of earthquakes N_Σ in the range of M_L = 2.5–5.5 and M_w = 3.0–7.0; the total annual quantity of released seismic energy ΣE, J; and angular coefficient b of earthquake recurrence graphs. Two explicit subperiods are revealed in the course of the seismic regime: quiescence in 1990–1996 before the Chi-Chi earthquake and in 1994–1997 before the March 2002 earthquake; in 1997–1999 and 1998–2002, respectively, seismic activation is observed. Due to the predominance of weak earthquakes during the Chi-Chi earthquake preparation, factor b appeared relatively higher (–1.16 on average); in contrast, before the March 2002 earthquake, due to the occurrence of foreshocks with M_w = 6.8–7.0, the factor b values appeared relatively lower (–0.55 and–0.74 for the quiescence and activation subperiods, respectively). Despite the fundamental difference in the seismotectonic situation between the domains where two mainshocks occurred and significantly difference energy ranges of the initial seismic events, the analysis results are similar for both earthquakes. In both cases, the mainshock occurred at the peak of released energy, which can be considered a coincidence. Solid verification of this positive tendency requires the accumulation of seismological statistics.