随机波浪中畸形波在三维岛礁地形上的试验研究

在试验水池中,开展了波浪在岛礁地形上演化问题的研究。首先在实验水池中建立了西太平洋某岛礁地形的模型,然后采用改进的JONSWAP谱,由造波机产生不同周期、波高的随机波浪。试验中观察到了不同类型畸形波生成的过程及不同波面形态的畸形波。对偏度、峰度及水深与畸形波要素H_m/H_s（H_m表示波列中的最大波高, H_s为有效波高）的关系进行了详细的分析,同时,对畸形波波高H_fr与偏度的关也进行了分析。通过对试验结果分析,发现峰度与畸形波要素i>H_m/H_s呈正相关, H_fr增大时相应的偏度也会呈现增大的趋势。此外,水深的变化剧烈时（如斜坡、海山位置）有助于畸形波的发生。     

A nonlinear model for nonbreaking shoaling random waves

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Sediment Flux of Particulate Organic Phosphorus in the Open Black Sea

The interannual variation of the monthly average (weighted average) concentrations of particulate organic phosphorus (P_POM) in the photosynthetic layer, oxycline, redox zone, and H₂S zone in the open Black Sea is estimated based on long-term observation data. The suspension sedimentation rates from the studied layers are assessed using model calculations and published data. The annual variation of P_POM sediment fluxes from the photosynthetic layer, oxycline, redox zone, and upper H₂S zone to the anaerobic zone of the sea and the correspondingly annual average values are estimated for the first time. A regular decrease in the P_POM annual average flux with depth in the upper active layer is demonstrated. A correlation between the annual average values of P_POM sediment flux from the photosynthetic layer and ascending phosphate flux to this layer is shown, which suggests their balance in the open sea. The results are discussed in terms of the phosphorus biogeochemical cycle and the concept of new and regenerative primary production in the open Black Sea.     

Variability of the carbonate system parameters in the coast-shelf zone of the East Siberian Sea during the autumn season

The publication presents the results of the studies on the carbonate system of the waters of the East Siberian Sea performed aboard R/V Ivan Kireev in September 2003–2004. It is shown that the aquatic area considered may be subdivided into two biohydrochemical provinces. The western part of the sea is a CO₂ supplier to the atmosphere, while its eastern part is a sink for CO₂. This is caused by the fact that the western part of the East Siberian Sea was affected by the waters of the southeastern part of the Laptev Sea, which were desalinated by riverine runoff, turbid, and enriched in the bioactive organic matter supplied into the water due to the coastal (and bottom) erosion. In the eastern part, cold waters of Pacific origin prevailed (saline, transparent, and productive), which caused a pronounced decrease in the partial pressure of CO₂(pCO₂) in the surface layer. In the frontal zone delimiting the desalinated shelf waters and those of the Pacific origin, the direction of the CO₂ flux between the atmosphere and the sea changed (from evasion to invasion). The interannual variability of the carbonate system parameters in the coastal-shelf zone of the East Siberian Sea was determined by the intensity of the propagation of the waters of different origins over the sea aquatic area caused by the atmospheric circulation, as well as by the riverine runoff intensity and the dynamics of erosion processes.     

Intraannual and long-term variations of the carbonate system of the aerobic zone in the black sea

We provide an expert quality assessment of the data for 1932–1993 and used these data to perform the numerical analysis of the carbonate system of the aerobic zone in the Black Sea. The intraannual and long-term variations of the carbonate system are studied in the abyssal part of the sea for 1960–1993. We propose explanations of the intraannual variations of the analyzed system for various layers of the aerobic zone and reveal long-term variations of the pH values, total alkalinity, and the ratios of the components of the carbonate system. We discover and explain the observed increase in the concentrations of TCO₂ and CO₂ and the partial pressure of carbon dioxide pCO₂, as well as a decrease in pH values and the concentration of CO₃²⁻ in waters of the aerobic zone of the Black Sea.     

Vertical distribution of the hydrogen sulphide sources in the Black Sea

Data on the diffusion coefficientK _zand the concentration of H₂S in the Black Sea are used to compute the depth distribution of the vertical flux, and the intensity of the H₂S sources and sinks. On average, the total production of H₂S in the Black Sea reaches 37×10⁶ t/year. The main bulk of H₂S is produced not at the bottom, but in the layer of 450–1300 m. Destruction of H₂S prevails above the 400 m layer. Dissolved oxygen penetrating the H₂S zone can oxidize only half of the hydrogen sulphide produced in the sea.Translated by Mikhail M. Trufanov.     

Vertical Structure of Currents in Northern Black Sea,October 2016

The paper presents the results of an analysis of hydrological data obtained on cruise 89 of the R/V Professor Vodyanitskii from September 30 through October 19, 2016, in the central area of the northern Black Sea. Currents were measured using a lowered acoustic Doppler current profiler (LADCP) to a depth of 350 m. Examples of the current velocity profiles and conditional density at individual stations are presented. The averaged characteristics of the vertical current structure in the seasonal and permanent pycnoclines are discussed. The isopycnally averaged kinetic energy (KE) demonstrates an almost linear dependence on the conditional density (σ_θ). In the seasonal pycnocline, EK = 0.2–0.013σ_θ; in the permanent pycnocline, EK = 0.12–0.007σ_θ. An interpretation is given for the variability of the kinetic energy with depth. It is shown that the maxima of the averaged vertical shear profile correspond to the occurrence depth of the seasonal and permanent pycnoclines. The mean Richardson number has a value of ~10 in the upper sea layer and decreases with depth, assuming a value of ~3 at the 300 m horizon. The estimate for the vertical turbulent diffusion coefficient from the simplified model shows its increase with depth.     

Nonlinear interaction of internal waves in the coastal zone of the Sea of Japan

Nonlinear interactions of the internal waves of a tidal period with low-frequency synoptic-scale internal waves are studied using instrumental measurements of the current in the coastal zone of the Sea of Japan. In the course of spectral analysis of the data of instrumental measurements, it is found that a maximum in the spectrum of the kinetic energy of coastal waters in the vicinity of the semidiurnal frequency ω₀ is surrounded by satellite maxima whose frequencies obey the relation ω _s = ω₀ ± Ω, where Ω is the characteristic frequency of synoptic-scale internal waves. The spectrum of the anticyclonic current component has a similar structure in the vicinities of the frequency ω₀ and its first and second harmonics. The general theory of nonlinear interactions of weakly dispersive waves is used to solve the problem of modulation and the parametric amplification of tidal internal waves in the coastal zone using low-frequency narrow-band internal waviness. As can be judged from the literature, the effect of parametric modulation of tidal internal waves by low-frequency synoptic-scale internal waves has been recorded in the coastal zone of a tidal sea for the first time.     

The distribution of oxygen and hydrogen sulfide in Black Sea waters during winter-spring period

Regularities of oxygen and hydrogen sulfide are examined, using the method of spatial isopycnic analysis. The contribution that ventilation of winter-time surface waters over the domes of cyclonic gyres makes to the transfer of O₂ towards the upper boundary of the constant pycnocline and to the oxicline layer is demonstrated. The paper provides spatial scales of this phenomenon and indicates the areas where the upper boundary of the anoxic layer in the Black Sea, relative to the conventional density, is located much higher compared with the rest of the sea. The suboxic zone is shown to be a specific feature of the O₂/H₂S distribution in the Black Sea waters, typical, at least, of the northern part of the basin. Analysis of the suboxic spatial variability in the vertical has been conducted. Translated by Vladimir A. Puchkin.     

Effect of skewness and kurtosis of sea-surface elevations on the accuracy of altimetry surface level measurements

We assess the influence of changes in the skewness and kurtosis of the distribution of elevations on a rough sea surface that were observed in field conditions on the accuracy of the recovery of the sea-surface level along the satellite trace. For different values of a significant height of surface waves, we obtain numerical estimates for the bias in relief recovery due to the simultaneous variation in skewness and kurtosis. It is shown that, with a decrease in kurtosis, the effect of skewness changes on the accuracy of altimetry measurements of the level increases. We note the limitations of the Gram-Charlier model in simulating the radar waveforms return from the sea surface.     

引入拖曳系数参数化的海冰自由漂流模拟研究

Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient(C_a) and oceanic drag coefficient(C_w).Parameterizations of drag coefficients rather than constant values provide us a way to look insight into the dependence of these characteristics on sea ice conditions.In the present study,the parameterized ice drag coefficients are included into a free-drift sea ice dynamic model,and the wind factor α and the deflection angle θ between sea ice drift and wind velocity as well as the ratio of C_a to C_w are studied to investigate their dependence on the impact factors such as local drag coefficients,floe and ridge geometry.The results reveal that in an idealized steady ocean,C_a/C_w increases obviously with the increasing ice concentration for small ice floes in the marginal ice zone,while it remains at a steady level(0.2-0.25) for large floes in the central ice zone.The wind factor α increases rapidly at first and approaches a steady level of 0.018 when A is greater than 20%.And the deflection angle θ drops rapidly from an initial value of approximate 80° and decreases slowly as A is greater than20%without a steady level like α.The values of these parameters agree well with the previously reported observations in Arctic.The ridging intensity is an important parameter to determine the dominant contribution of the ratio of skin friction drag coefficient(C_s' /C_s) and the ratio of ridge form drag coefficient(C_r'/C_r) to the value of C_a/C_w,α,and θ,because of the dominance of ridge form drag for large ridging intensity and skin friction for small ridging intensity among the total drag forces.Parameterization of sea ice drag coefficients has the potential to be embedded into ice dynamic models to better account for the variability of sea ice in the transient Arctic Ocean.     

A numerical experiment on modelling synoptic eddies in the Black Sea during the summer season

An energetically-balanced model has been used to perform an eddy-resolving experiment on the calculation of the baroclinic circulation in the Black Sea. As the initial and boundary conditions, historical data on the density and tangential wind stress for the summer season have been used. Following the integration of a set of model equations, an array of anticyclonic eddies formed on days 50–60 on the margins of the Black Sea rim current. Off the Caucasus, Crimean, and Bulgarian coast, anticyclonic eddies are shown to be quasi-stationary. The north-western Black Sea and Anatolia coastal zone are areas of Black Sea rim current instability, where synoptic eddies — both cyclonic and anticyclonic — are generated.Translated by Vladimir A. Puchkin.     

Wave modelling in the vicinity of submerged breakwaters

This paper describes a simple method for modelling wave breaking over submerged structures, with the view of using such modelling approach in a coastal area morphodynamic modelling system.A dominant mechanism for dissipating wave energy over a submerged breakwater is depth-limited wave breaking. Available models for energy dissipation due to wave breaking are developed for beaches (gentle slopes) and require further modifications to model wave breaking over submerged breakwaters.In this paper, wave breaking is split into two parts, namely: 1) depth-limited breaking modelled using Battjes and Janssen's (1978) theory [Battjes, J.A. and Jannsen, J.P.F.M. (1978). Energy loss and setup due to breaking of random waves. Proceedings of the 16th Int. Conf. Coast. Eng., Hamburg, Germany, pp. 569-587.] and 2) steepness limited breaking modelled using an integrated form of the Hasselmann's whitecapping dissipation term, commonly used in fully spectral wind–wave models. The parameter γ₂, governing the maximum wave height at incipient breaking (H_max = γ₂d) is used as calibration factor to tune numerical model results to selected laboratory measurements. It is found that γ₂ varies mainly with the relative submergence depth (ratio of submergence depth at breakwater crest to significant wave height), and a simple relationship is proposed. It is shown that the transmission coefficients obtained using this approach compare favourably with those calculated using published empirical expressions.     

Nonlinear properties of laboratory wind waves at energy containing frequencies

Nonlinear properties of wind waves in a wind-wave tunnel are investigated by measuring the probability density distribution of surface elevation. The surface elevation distribution of raw records are found to have a positive skewness (K ₃=0.21 to 0.43) and a negative kurtosis (K ₄=–0.74 to –0.41) with magnitude depending of fetch and wind speed. The values of skewness are in qualitative agreement with a prediction of the weak interaction theory for a random wave field incorporating the effects of second harmonics (Tayfun, 1980), but the values of kurtosis are different in sign from the prediction.To examine the nonlinear properties of energy containing components, higher harmonic components are excluded from the wave records by using a kind of a band-pass filter. The surface elevation distributions of the filtered waves show a sharp decrease in skewness , but the distributions remain highly non-Gaussian with a large negative kurtosis almost independent of the fetch and wind speed . It is concluded that the negative kurtosis is due to the non-random character of the phase and amplitude among the energy containing components, and that nonlinear interactions occur amongst the energy containing frequencies.     

Meteorological forcing of long-term temperature variations of the Dutch coastal waters

Time series of observations of the sea surface temperature (SST) at 12 stations in the Dutch coastal zone are analyzed to establish whether an earlier published nearly 150 year long SST time series from the Marsdiep tidal inlet is representative for the whole Dutch coastal zone. The annual cycles (SST range and phase) as well as the long-term SST trends at decadal scales from other estuaries agree with the Marsdiep time series. An increasing SST trend since 1982 is a phenomenon of the whole Dutch coastal zone. In order to increase the understanding of the causes of the observed SST variability, a multiple linear regression model is constructed, which links locally determined seasonal meteorological and oceanographic forcing factors to the seasonal mean SST. The oceanographic forcing factor is the SST value from the preceding season, representing persistence due to thermal inertia of the sea. Season to season changes of the atmospheric circulation, connected with SST variability, are represented by seasonal mean wind components as forcing factors, e.g. the western winds in winter which bring relatively warm air masses to Western Europe. For the seasons where shortwave solar radiation is the dominant term in the local heat budget (spring and summer), the number of bright sun hours is used as forcing factor, roughly representing the effects of changing cloudiness. The annual mean SST, derived from the regression models for the four seasons, applied to 4 locations along the Dutch coast, correlates quite well, not only for the year to year variability (R = 0.88) but also for the longer-term SST trends (R = 0.95). An explicit local greenhouse effect is not required as separate forcing factor to explain the recent warming trend of Dutch coastal waters starting in the early 1980s; coincident variations in wind statistics and cloudiness are a sufficient explanation.     

Experiment of Wind Wave Parameter Research on the Black Sea Shelf

The article presents information on the current experiment of research on wind wave parameters in the Black Sea coastal zone. Two wave-meter devices are the part of the measuring equipment of the Black Sea testing site Gelendzhik of the Shirshov Institute of Oceanology (IO RAS). The integral characteristics of wind waves accumulated and obtained in real time may be in demand by experts in operational and satellite oceanography.

     

Technique for Simulation of Black Sea Circulation with Increased Resolution in the Area of the IO RAS Polygon

A numerical technique is presented for simulating the hydrophysical fields of the Black Sea on a variable-step grid with refinement in the area of IO RAS polygon. Model primitive equations are written in spherical coordinates with an arbitrary arrangement of poles. In order to increase the horizontal resolution of the coastal zone in the area of the IO RAS polygon in the northeastern part of the sea near Gelendzhik, one of the poles is placed at a land point (38.35° E, 44.75° N). The model horizontal resolution varies from 150 m in the area of the IO RAS polygon to 4.6 km in the southwestern part of the Black Sea. The numerical technique makes it possible to simulate a large-scale structure of Black Sea circulation as well as the meso- and submesoscale dynamics of the coastal zone. In order to compute the atmospheric forcing, the results of the regional climate model WRF with a resolution of about 10 km in space and 1 h in time are used. In order to demonstrate the technique, Black Sea hydrophysical fields for 2011–2012 and a passive tracer transport representing self-cleaning of Gelendzhik Bay in July 2012 are simulated.     

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.     

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.     

Skewed Occurrence Frequency of Water Temperature and Salinity in the Subarctic Regions

In a previous paper (Oguma and Nagata, 2002), it was shown that frequency distributions of temperature and salinity in the sea off Sanriku Coast, Japan are skewed, and sometimes observed values exceed m + 5σ (m = mean, σ = standard deviation). This means that, if we apply a 3σ criterion for a range check, many real data would be lost. We have expanded our analysis to the subarctic North Pacific, the subarctic North Atlantic and their surrounding areas, by computing the distributions of skewness and kurtosis. It is found that the region of high positive skewness extends in an east-north-east direction in the Mixed Water Region from off Sanriku, and reaches to about 155°E. A high negative skewness zone is recognized along the southern margin of the Kuroshio Extension. These are thought to be generated by the breaking of the meander of the Kuroshio Extension and subsequent ejection of warm and cold eddies to the north and south, respectively. Other high positive skewness areas are found to the south of Kuril Islands and in the Japan Sea. These are generated due to very sharp vertical gradients of temperature and salinity. The situation in the North Atlantic is very similar to the North Pacific, though the detailed nature is changed due to differences of oceanographic condition. The effect of grid size on the skewed nature of the distribution is also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.