海南岛西岸上升流对波浪混合的敏感性研究

The coupled ocean–atmosphere–wave–sediment transport(COAWST) modeling system is employed to investigate the role of wave-mixing playing in the upwelling off the west coast of Hainan Island(WHU). Waves,tides and sea surface temperature(SST) are reproduced reasonably well by the model when validated by observations. Model results suggest the WHU is tidally driven. Further investigations indicate that inclusion of wave-mixing promotes the intensity of the WHU, making the simulated SST become more consistent with remote-sensed ones. Dynamically, wave-mixing facilitates the "outcrop" of more upwelled cold water, triggering stronger WHU and leading to a three-dimensional dynamical adjustment. From the perspective of time, wavemixing contributes to establishing an earlier tidal mixing front strong enough to generate WHU and that is, WHU may occur earlier when taking wave-mixing into consideration.     

Upwelling and ocean structures off Algoa Bay and the south-east coast of South Africa

As the Agulhas Current flows along the south-east coast of South Africa, a number of processes operate that bring cold, deep water up onto the narrow shelf. As a consequence, upwelling along the coastline is enhanced farther southward and downstream. This situation is investigated off Algoa Bay and along the south-east coast to Port Alfred, where measurements demonstrate that marked temperature variability occurs at the coastline, particularly in summer when temperature structures are more intense and easterly-component winds more common. There is no indication that upwelling is more prevalent at Port Alfred; increasing variability farther south is evident at Woody Cape/Cape Padrone, where the coastline veers westwards, forming the eastern boundary of Algoa Bay. Here it is found that, after a wind change to north-easterly, cold water is upwelled along the shoreline between 19 hours and 2.5 days later. Such upwelling progresses north-eastwards with the movement of the wind and weather systems, although colder water also moves south-westwards into Algoa Bay. Winds, currents, sea level and sea temperatures are highly correlated, with fluctuations in sea level measuring >50 cm being associated with coastal trapped waves (CTWs). Such barotropic wind-driven CTWs are frequently active during upwelling, although it is unclear whether there is any interaction between the two phenomena.     

An investigation of tsunami source mechanism off the coast of central Peru

The source mechanism of the tsunami generated by the earthquake of 17 October, 1966 off the coast of central Peru was inferred by studying the seismic and oceanic phenomena associated with this event. The seismic mechanism was deduced from geologic structure, seismic intensities, energy releases, spatial distribution of aftershocks, and fault-plane solutions. Using this information and empirical relationships of seismic parameters, the fault length, azimuthal orientation of the tsunamigenic area, and initial tsunami height, were obtained. From the tsunami arrival times at selected stations and from a reverse wave-refraction technique, the limits of the tsunami-generating area were estimated. Using these source dimensions, an estimate of the tsunami energy was obtained. The spatial distribution of aftershocks associated with the main earthquake and the earthquake strain-release pattern correlated well with known seismotectonic trends and the seismic-velocity structure anomalies which are characteristic of thrust fault systems at continent-ocean boundaries. The investigation revealed that the tsunamigenic area was on the continental shelf off Peru, northwest of Lima, in the western part of an active seismic belt between the Andean Mountain block and the Peru-Chile trench. This area is considered to be one of three distinct seismic zones in the Peruvian upper mantle and has been responsible for a number of tsunamigenic earthquakes within recorded history. The aftershock distribution and strain-release patterns suggest that the earthquake fault was a seaward extension of a fault system which has a pronounced surface expression in the Tertiary formations of the area near Ancon, Peru. The limits of the tectonic displacements and the tsunami-generating area were determined by a reverse wave-refraction method, refracting waves from Chimbote, Callao-Lima, San Juan, and Honolulu. The investigation revealed that the tsunami was generated by displacements of crustal blocks with a total area of 13,000 sq. km. Seismic and water motion data indicated that the uplifted portion of the crustal block was on the continental side of the rift. The energy of the main earthquake was estimated to be 1.122·10²³ ergs. The energy of the aftershocks was estimated to be 2.357·10²⁰ ergs. The tsunami energy was calculated to be 6.8·10¹⁹ ergs, or $\text{1}\text{1,650}$ of the earthquake energy.     

夏季闽浙沿岸上升流的数值研究

将闽浙沿岸作为研究海区,采用σ坐标下三维斜压非线性的浅海陆架数值模式研究风、边界流(台湾暖流、黑潮、长江冲淡水)、潮及地形等动力因子对上升流形成的影响。结果得出：西南季风是影响夏季闽浙沿岸近海岸区域上升流形成的重要因子;台湾暖流对闽浙沿岸上升流的形成起主要作用：黑潮对台湾岛以东海域上升流的形成影响较大;长江冲淡水不利于夏季闽浙沿岸上升流的形成,尤其是浙江沿岸;地形对闽浙沿岸上升流的形成作用较显著;M^2分潮对闽浙近海岸区域及台湾澎佳屿附近海域上升流的形成影响较大;本文在对夏季闽浙沿岸海区水文结构的模拟中,同样得出夏季沿岸的低温高盐区与本文所计算出的三个较强的上升中心一致。     

Wave hindcasting off the coast of Portugal

A study was conducted applying a second-generation wave model to predictions in coastal zones. The model was calibrated with wave measurements conducted off the Portuguese coast, for a period of 6 months. The wind fields used in the calculation were supplied by the European Centre for Medium Range Weather Forecast (ECMRWF). The calibrated model allows good predictions of significant wave height. Satisfactory comparisons have been made with predictions of the WAM model     

Upwelling variability along the southern coast of Bali and in Nusa Tenggara waters

Spatial and temporal variation of upwelling along the southern coast of Bali and in the Nusa Tenggara waters — Indonesia was studied by using satellite image data of sea surface temperatures and chlorophyll-a from September 1997 to December 2008. This study clearly reveals annual upwelling in the regions from June to October, associated with the southeast monsoon cycle, with the sea surface temperature (chlorophyll-a concentration) being colder (higher) than that during the northwest monsoon. In addition, this study also shows that the upwelling strength is controlled remotely by ENSO and IOD climate phenomena. During El Niño/positive IOD (La Niña/negative IOD) periods, the Bali — Nusa Tenggara upwelling strength increases (decreases).     

Continental shelf waves off the Fukushima coast

Numerical experiments are performed on shelf waves forced by wind stress with a spectral peak around a period of 100 hr. Water depth in the numerical model is a function of offshore distance only and resembles a bathymetric profile off the Fukushima coast. A pair of vortices alined in the offshore direction and a large vortex are reproduced and they propagate southward outside the forced region. Judging from the propagation speed, the former corresponds to the second-mode and the latter to the first-mode shelf waves. In the forced region, the propagation speed of a trough and a ridge is slow, 3–5km hr^–1. These propagation characteristics reproduce those observed along the Fukushima coast and this propagation speed corresponds to that of second-and third-mode shelf waves. Thus, it is concluded that the periodical current fluctuations observed in the inshore region along the Fukushima coast are due to motions associated with the second-and third-mode shelf waves.     

Continental shelf waves off the Fukushima coast

Past observations and theories have indicated the importance of the constitution of the lowest-mode of shelf waves to the velocity field. However, significant contributions of the higher mode waves to current velocity fluctuations in the vicinity of the coast are suggested in observational results obtained along the Fukushima coast in Pt. I of this study (Kubota et al., 1981). To understand the importance of the higher modes, the generation of shelf waves is investigated theoretically by two methods. First, the generation of long shelf waves by monochromatic forcing is examined, and it is concluded that near the coast the second mode's contribution to the longshore velocity is the largest for the Fukushima coast. Second, the response of shelf waves to broad-band forcing is investigated by taking the dispersive characteristics of shelf waves into consideration. It is concluded that shelf waves with zero group velocity are selectively excited if the forcing has a broad-band spectrum. According to observational results obtained along the Fukushima coast, the wind spectrum has a broad peak at about 100 hours (Kubota et al., 1981). Since the third mode of shelf waves has zero group velocity around the period of 100 hours, the third mode can be selectively generated off the Fukushima coast. From this it is suggested that the Fukushima coast is in the forced region and that observed current fluctuations are motions associated with the second- and third-mode shelf waves.     

Zooplankton research off Peru: A review

A review of zooplankton studies conducted in Peruvian marine waters is given. After a short history of the development of zooplankton research off Peru, we review zooplankton methodology, taxonomy, biodiversity, spatial distribution, seasonal and interannual variability, trophodynamics, secondary production, and modelling. We review studies on several micro-, meso-, macro-, and meroplankton groups, and give a species list from both published and unpublished reports. Three regional zooplankton groups have been identified: (1) a continental shelf group dominated by Acartia tonsa and Centropages brachiatus; (2) a continental slope group characterized by siphonophores, bivalves, foraminifera and radiolaria; (3) and a species-rich oceanic group. The highest zooplankton abundances and biomasses were often found between 4–6°S and 14–16°S, where continental shelves are narrow. Species composition changes with distance from the shore. Species composition and biomass also vary strongly on short time scales due to advection, peaks of larval production, trophic interactions, and community succession. The relation of zooplankton to climatic variability (ENSO and multi-decadal) and fish stocks is discussed in the context of ecological regime shifts. An intermediate upwelling hypothesis is proposed, based on the negative effects of low upwelling intensity in summer or extremely strong and enduring winter upwelling on zooplankton abundance off Peru. According to this hypothesis, intermediate upwelling creates an optimal environmental window for zooplankton communities. Finally, we highlight important knowledge gaps that warrant attention in future.     

Complex BSR pattern in the Yaquina Basin off Peru

The distribution of gas and gas hydrate within the central Yaquina Basin, a forearc basin at the Peru convergent margin, can be estimated from the interpretation of high-resolution reflection seismic data. The strongest bottom simulating reflector (BSR) is observed where the base of gas hydrate stability (BGHS) parallels strata. Where the BGHS crosscuts strata, only a small amount of gas is present beneath the BGHS. Anisotropic permeability plays a key role in controlling methane supply. Where present-day tectonic activity is observed, faults and, consequently, gas reach up to the seafloor where chemoherms formed. The warm fluids contort the BGHS and, consequently, the BSR is shifted upward. Increased heat flux and/or sediment interval velocity in this region is likely. Bright spots align beneath the actual BGHS and mark the depth of a paleo-BSR, which can be correlated with sedimentation of a particular sequence. There is clear evidence for free gas being present within the gas hydrate stability zone.     

Real-time wave forecasts off the western Indian coast

The wave observations at three locations off the west coast of India have been analyzed using artificial neural network (ANN) to obtain forecasts of significant wave heights at intervals of 3, 6, 12 and 24 h. The most appropriate training method requiring an input of four observations spread over previous 24 h has been selected after considerable trials. Further, the networks are trained after filling in the missing information. Larger gaps in data are filled in using spatial mapping involving observations at nearby locations, while relatively smaller gaps are accounted for by the statistical technique of multiple regressions in temporal mode. It is found that by doing so the long-interval forecasting is tremendously improved, with corresponding accuracy levels becoming close to those of the short-interval forecasts. If the amount of gaps is restricted to around 2% per year or so it is possible to obtain 12 h ahead forecasts with 0.08 m accuracy on an average and 24 h ahead forecast with a mean accuracy of 0.13 m. However, in harsher environments the prediction accuracy can change.     

Demersal communities off the west coast of South Africa

To describe demersal communities off the west coast of South Africa, collections of all species of fish, cephalopods and crustaceans made during four cruises in the area during January and July have been analysed. Hierarchical classification methods were employed to determine species and sample associations. The results showed that the species could be split into two main groups, the first containing Merluccius paradoxus (the dominant species both in abundance and frequency of occurrence) and other species normally found in deep (> 380 m) water. The second group is represented by species that live on the continental shelf, M. capensis being the most abundant. The boundary separating the deep-sea community from that of the shelf follows approximately the 385-m isobath. Seasonal variations in the number of main associations as well as in their spatial location are documented.     

Pollen analysis of marine sediments off the Washington coast

Pollen diagrams of postglacial sediments from the continental terrace off the Washington coast reveal trends similar to those observed in continental sections of postglacial age from the Pacific Northwest and appear sufficient for correlation with terrestrial deposits. The absolute pollen frequency (APF) varies from 3000 to 15000 grains/g. Maximum number of pollen grains (500–800/cm²/year) accumulated during the Hypsithermal.     

Characteristics of storm waves off the Mediterranean coast of Israel

A two-year series of directional wave measurement off the Eastern Mediterranean coast of Israel reveals an abundance of high storm waves. Some of these waves have significant height in excess of 5 meters and periods as long as 15 sec.The evolution of the storm waves is described and related to the growth and paths of the storm fronts in Mid-Mediterranean. Shorter-period waves are found to always lead the arrival of longer-period swell. This characteristic is explained by a short decay distance and/or a high migration velocity of the storm front.The scatter plot of significant wave height vs period for the recorded events of each storm describes an open-loop time sequence. The difference in period between that of the peak height event and the period of a fully arisen sea of the same height is found to be indicative of the true decay distance the waves have travelled.     

Estimation of insolation over the Pacific Ocean off the Sanriku coast

Surface solar radiation over the Pacific Ocean off the Sanriku coast has been estimated using Visible and Infrared Spin Scan Radiometer data supplied by the Geostationary Meteorological Satellite 5 for September, 1996 to June, 1997, when the Ocean Color and Temperature Scanner was functioning. The hourly and daily insolation is estimated with a spatial resolution of 0.01-degree grid. Thein situ surface short wave radiation obtained by the research vessel,Kofu-Maru belonging to the Japan Meteorological Agency is used for validation of the estimated insolation. It is shown that the estimated hourly and daily insolation has an rms (root mean square) error of 17.05% and 8.13%, respectively, which are the ratios between the rms error (W/m²) and the mean insolation (W/m²).     

Observation of the anticyclonic eddy formation off the Black Sea coast

An anticyclonic eddy with a horizontal dimension of 20 km travelling north-westwards at a speed of 10 cm/s has been found during an experiment carried out off the Black Sea coast. Dynamic instability owing to horizontal velocity shear could be the reason for its origin. The eddy's passage favours the development of shear instability and the generation of short-period internal waves.Translated by Mikhail M. Trufanov.     

The Preliminary Investigation on the Red Tides in the Coastal Upwelling Observation Area off Zhejiang Province

This paper reports the observational results of the red tides in the coastal upwellingarea (27°30'--30°N, west of 124°E) off Zhejiang Province in August 1981. As the distri-butions of the planktons numbers are compared with those of the hydrography and me-teorology during the onset of the red tides, some features of the hydrology and ecologyare presented. And the constituents of the red tides planktons are analysed. Through the     

Poleward shift of the coastal upwelling region off the California coast

Yoshida (1967) pointed out that the coastal upwelling region may not coincide with the intense longshore wind region and shift poleward. In order to clarify this poleward shift from the existing data, the monthly mean distributions of the offshore Ekman transport and the coastal upwelling intensity are estimated along the California coast from U. S. Daily Weather Maps and from the CCOFI data in 1949, respectively. The results show that the center of the coastal upwelling region is generally shifted to the north from the position of the maximum offshore Ekman transport. The detailed discussions are given for the case of August 1949 when the shift is seen most clearly.