Influence of the Kuroshio Fluctuations on Sea Level Variations along the South Coast of Japan

The correlation between the Kuroshio and coastal sea level south of Japan has been examined using the altimetry and tide gauge data during the period 1992–2000. The sea level varies uniformly in a region bounded by the coast and the mean Kuroshio axis, which stretches for several hundred kilometers along the coast. These variations are related with the Kuroshio velocity, as coastal sea level decreases (or increases) when the Kuroshio is faster (or slower). To the east of the Kii Peninsula, where sea level variations are different from these to the west, movement of the Kuroshio axis additionally affects coastal sea level variations.     

Coastal Disturbance in Sea Level Propagating along the South Coast of Japan and Its Impact on the Kuroshio

The coastal sea level propagating westward along the south coast of Japan and the impact of the disturbance on the generation of the Kuroshio small meander have been examined. The propagation occurs in sea level variations for periods shorter than 10 days and is remarkable for periods of 4–6 days. Characteristics of the 4–6 day component have been studied using the extended empirical orthogonal function (EEOF). The first and second modes of EEOF are almost in-phase throughout the south coast of Japan. The higher four modes of EEOF are significantly excited when the Kuroshio takes the non-large-meander path, and propagate westward with phase speeds of 2.8 m s⁻¹ (third and fourth modes) and 1.6 m s⁻¹ (fifth and sixth modes) in the Kuroshio region west of Mera in the Boso Peninsula. The analysis shows that more than 70% of the small meanders generate in two months after a significant propagating disturbance reaches south of Kyushu when the velocity of the Kuroshio is high. This effect of coastal disturbance is examined by numerical experiments with a 2.5-layer model in which coastal disturbance is excited by vertical displacement of the upper interface. The result is that offshore displacement of the Kuroshio occurs southeast of Kyushu only in the case of significant upward displacement of the interface under the influence of a high Kuroshio velocity. The significant coastal disturbance, which is associated with upward displacement of the density interface, and a high Kuroshio velocity can therefore be important factors in generating small meanders.     

渤海海流概况及其输沙作用初析

本文讨论了渤海及黄河口附近海域的海洋动力状况，潮流和风暴急流是输送黄河入海泥沙的主要动力。     

渤海、黄海浮游植物生态的研究

本文以1984～1985年渤海、黄海海洋图集综合调查的资料为主,收集和分析了我国黄海中部以西海域有关浮游植物调查研究资料。可以看出,以往我国对黄海中部以西海域浮游植物群落结构和生态特征进行了较详细的研究,初步揭示了该海域浮游植物种类和数量分布的基本面貌,并了解了引起赤潮的种类和赤潮发生的基本情况,这一切都为开展黄海大海洋生态系的研究奠定了基础。     

Technical Issues and Recommendations Related to the Installation of Continuous GPS Stations at Tide Gauges

Geodesists around the world have begun installing continuous GPS (CGPS) stations at tide gauges in order to determine the exact position of these tide gauges and, in particular, the vertical velocity of the land or the seafloor underlying each tide gauge. The goal is to make these measurements in a well-defined global reference frame. The scientific applications of these measurements include the calibration of satellite altimeters and the removal of crustal motion signals from long time series of sea level change. In this article we focus on the technical issues associated with this agenda, including site selection, instrumentation, monumentation, ancillary measurements, and the tide gauge leveling program. There is no universally best approach to building CGPS stations at tide gauges. Therefore we emphasize the various trade-offs that typically occur, and give general recommendations and rules of thumb based on recent installations and experience. Additional information can be found at the CGPS@TG website.     

Spatial variability in precipitation within the Hilton Experimental Site,Shropshire, UK (1982–2006)

Accurate precipitation measurements are essential for many hydrological and hydrogeological management strategies. Precipitation at the Hilton Experimental Site has been regularly measured since 1982. This paper summarises 157 rain gauge years of precipitation data, recorded between 1982 and 2006, using 11 rain gauges on the 0·5 hectare site. Precipitation varied markedly within the site. Precipitation totals were notably different between two adjacent rain gauges, the mean difference being 0·3% of the total. Variations in mean annual precipitation within the site were ?8%. Spatial variations in wind turbulence appeared to be the main factor influencing intra‐site variability. Precipitation totals varied with gauge exposure, with surface level gauges receiving ?5·9% more precipitation than standard rain gauges, the difference being less lower down the slope. On a steep (～15° ) slope, basal sections had 2·5–7·9% more precipitation. Upper gauges received less, probably due to turbulence as increased exposure on the top of the slope resulted in precipitation being carried over the gauge orifice. Results confirm that due attention must be given to the inherent variability of precipitation amounts when calculating precipitation inputs. Copyright © 2008 John Wiley & Sons, Ltd.     

Development of wavelet network model for accurate water levels prediction with meteorological effects

Accurate water levels modeling and prediction is essential for safety of coastal navigation and other maritime applications. Water levels modeling and prediction is traditionally developed using the least-squares-based harmonic analysis method that estimates the harmonic constituents from the measured water levels. If long water level measurements are not obtained from the tide gauge, accurate water levels prediction cannot be estimated. To overcome the above limitations, the current state-of-the-art artificial neural network has recently been developed for water levels prediction from short water level measurements. However, a highly nonlinear and efficient wavelet network model is proposed and developed in this paper for water levels modeling and prediction using short water level measurements. Water level measurements (about one month and a week) from six different tide gauges are employed to develop the proposed model and investigate the atmospheric changes effect. It is shown that the majority of error values, the differences between water level measurements and the modeled and predicted values, fall within the −5 cm and +5 cm range and root-mean-squared (RMS) errors fall within 1–6 cm range. A comparison between the developed highly nonlinear wavelet network model and the harmonic analysis method and the artificial neural networks shows that the RMS of the developed wavelet network model when compared with the RMS of the harmonic analysis method is reduced by about 70% and when compared with the RMS of the artificial neural networks is reduced by about 22%. It is also worth noting that if the atmospheric changes effect (meteorological effect) of the air pressure, the air temperature, the relative humidity, wind speed and wind direction are considered, the performance accuracy of the developed wavelet network model is improved by about 20% (based on the estimated RMS values).     

GPS浮标天线高的动态标定方法

针对组装式全球定位系统浮标因每次加载设备不同,浮标体质心与吃水存在变化的问题,该文提出一种借助全球定位系统动态后处理和验潮仪的浮标全球定位系统天线高的动态标定方法。实验表明,该方法能有效测定全球定位系统浮标天线相位中心至吃水面距离,标定精度优于1cm,并可应用于所有类型全球定位系统浮标的天线高标定和校核。     

雨量计加热装置研制

雨量计是地震监测中的辅助仪器,用于测量大气降水量。北方冬季严寒,固态降水不能被及时有效记录,且在融化过程中可能会凝结在雨量计传感器中,造成传感器不能记录甚至被冻坏。为此设计一种加热装置,通过加装智能识别、桶内加热器、延时等装置,对现有非融雪式雨量计进行改造,将固态降水有效转化为液态降水,从而得到降水量的真实记录。     

Sunlight and tidal interaction as a mechanism of carbon transport in an ice-covered region: Results of a coupled ice–ocean ecosystem model

In order to clarify the mechanism of carbon transport in an ice-covered ecosystem in Lake Saroma (44^°N${44}^{°}\mathrm{N}$, 143^°E${143}^{°}\mathrm{E}$, Hokkaido, Japan), a three-dimensional numerical calculation using a coupled ice–ocean ecosystem model was conducted. This model comprises an ocean ecosystem model, an ice ecosystem model, and equations for the coupling between ice and ocean. Comparisons of calculated results with observational data confirm that the calculation well reproduced the in situ phenomena with respect to tides, tidal currents, concentrations of POC and chlorophyll a in ice and in water, and sinking fluxes beneath the ice. The analysis of the organic carbon budget based on the calculation reveals that tide-induced transport, the enhancement of biological production in a pelagic system, and the physical release of organic matter from ice associated with ice-melting are important factors affecting the carbon transport during the ice-melting season. The carbon transport has a one-day time cycle. This is because principal driving forces are sunlight, and diurnal tides. The described mechanism of “sunlight and tidal pumping” is one of the most important features of carbon transport in a coupled ice–water ecosystem.