Restoration of an inner-city stream and its impact on air temperature and humidity based on long-term monitoring data

Spatiotemporal changes in air temperature and humidity associated with the restoration of an inner-city stream in Seoul, Korea, are investigated based on long-term monitoring data. The Cheonggye stream, covered under a concrete structure for 46 years, was restored in 2005 and runs 5.8 km eastward through a central region of Seoul. Long-term monitoring of the air temperature and relative humidity was made along the stream throughout the restoration and across the stream after the restoration. The area along the stream had a higher air temperature than the entire metropolitan area. The temperature anomaly between the monitoring area and the surrounding metropolitan area was 0.13^oC lower on average at the center of the stream after the restoration. The stream's effect on the air temperature was also evident in the temperature distribution along a street traversing the stream. The relative and specific humidities were increased due to the restoration. The restored stream modified the nearby urban climate in the opposite direction compared to urbanization. The results could be used as a model case in mitigating urban climate by a stream in future urban planning practices.     

Seasonal climate predictability with Tier-one and Tier-two prediction systems

In this study seasonal predictability of Tier-one and Tier-two predictions are evaluated and compared. Through the comparison of these two predictions, it is demonstrated that the air–sea coupled process is an important factor not only for climatological simulation but also for seasonal predictability. In particular, the air–sea coupling plays a crucial role over the warm pool region, as the atmosphere tends to lead the ocean in anomalous variability. In this region, the Tier-one prediction has better climatology compared to the Tier-two prediction despite the presence of a climatological SST bias. Furthermore, the Tier-one has a relatively higher seasonal predictive skill than that of the Tier-two although its SST prediction skill is relatively poor. It is suggested that the air–sea coupled process plays a role to reduce both the climatological and anomalous biases in the uncoupled AGCM by means of the negative feedback of the SST-heat flux-precipitation loop. Using the CliPAS and DEMETER seasonal prediction data, the robustness of these results are demonstrated in the multi-model frame works. This paper is a contribution to the AMIP-CMIP Diagnostic Sub-project on General Circulation Model Simulation of the East Asian Climate, coordinated by W.-C. Wang.

---

Geothermal gradient of the upper mantle beneath Jeju Island, Korea: Evidence from mantle xenoliths

Abstract Ultramafic xenoliths found in alkali basalts from Jeju Island, Korea are mostly spinel lherzolites accompanied by subordinate amount of spinel harzburgites and pyroxenites. The combination of results from a two-pyroxene geothermometer and Ca-in-olivine geobarometer yields temperature–pressure (T–P) estimates for spinel peridotites that fall in experimentally determined spinel lherzolite field in CaO-Fe-MgO-Al₂O₃-SiO₂-Cr₂O₃ (CFMASCr) system. These T–P data sets have been used to construct the Quaternary Jeju Island geotherm, which defines a locus from about 13 kbar at 880°C to 26 kbar at 1040°C. The geothermal gradient of Jeju Island is greater than that of the conventional conductive models, and may be as a result of a thermal perturbation by the heat input into the lithospheric mantle via the passage and emplacement of magma. Spinel–lherzolite is the main constituent rock-type of the lithospheric mantle beneath Jeju Island. Pyroxenites may be intercalated in peridotites at similar depth and temperature as re-equilibrated veins or lenses.     

Arsenic and metal contamination of water resources from mining wastes in Korea

 Water resources near a gold-mine waste site were studied for the distribution and contents of contaminants, and their behavior in the surface and groundwater systems. Arsenic, cadmium, and manganese were identified with levels exceeding the drinking water guidelines of WHO (World Health Organization), and their distribution depended upon the differences in source materials and in spatial pH variations. Originating from arsenopyrite, concentrations of dissolved arsenic were controlled by sorption with amorphous iron (Fe(OH)₃) and carbonate minerals. Cadmium and manganese were derived from the mineral phase including sphalerite (ZnS), otavite (CdCO₃), and rhodochrosite (MnCO₃); their concentrations in water resources were limited by the solubility of mineral phases. All of these processes are significantly pH-dependent, implying that a small decline in pH could result in a drastic increase in contaminant concentrations and become a pollution threat to the water resources of the Gubong area. Received: 13 December 1999 · Accepted: 21 March 2000     

Hydrodynamics and sedimentation induced by large-scale coastal developments in the Keum River Estuary, Korea

The macro-tidal Keum River Estuary located in the eastern Yellow Sea has been suffering siltation and morphological change since 1994. To understand the effects of the large-scale coastal developments on the sedimentation processes in the estuary, hydrodynamic and sedimentary data collected from 1985 to 2002 were analyzed and numerical experiments of hydrodynamics were performed. The sedimentation rate in the estuary increased by a factor of 1.9, from 3.5 × 10⁶ to 6.7 × 10⁶ m³ y⁻¹, after the construction of a dam in the upper reaches of the estuary in 1994. Large part of the estuary is veneered by the muddy sediments noticeably, which were rarely found before dam construction. Since then, siltation has concentrated in the upper estuary rather than the lower. The upstream transport and accumulation of fine-grained sediments is due to: (1) the change to flood-dominance in the main channel, i.e. the relative intensification of flood current and the flood-directed residual current; and (2) the decrease in transport capacity in the upper estuary, i.e. the marked decrease in current velocity, which was induced by dam construction. The former has resulted in the ebb-dominance of the Gaeya channel, a distributary in the north of the main channel. The tidal pumping of fine sediments was reinforced not by the freshwater/saltwater interaction but by the residual tidal circulation. The sediment fluxes observed in 2001–2002 demonstrate year-round net inflow both at the entrance of the jetties and at the Gaeya channel, which implies that the sediments delivered by the Keum River are entirely confined to the estuary, incapable of escaping to the sea. The net inward transport of fine sediments may accumulate pollutants adsorbed to or absorbed in the sediment grains in the estuary, thus deteriorating the benthic environment gradually and the water quality eventually.     

A synchronously coupled tide–wave–surge model of the Yellow Sea

A coupled wave–tide–surge model has been established in this study in order to investigate the effect of tides, storm surges, and wind waves interactions during a winter monsoon on November 1983 in the Yellow Sea. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM-Cycle 4, and the two-dimensional tide–surge model. The surface stress generated by interactions between wind and waves is calculated using the WAM-Cycle 4 directly based on an analytical approximation of the results obtained from the quasi-linear theory of wave generation. The changes of bottom friction factor generated by waves and current interactions are calculated by using simplified bottom boundary layer model. The model simulations showed that bottom velocity and effective bottom drag coefficient induced by combination of wave and current were increased in shallow waters of up to 50 m in the Yellow Sea during the wintertime strong storm conditions.     

Characterization of proteins in the muscle of<Emphasis Type="Italic">limanda yokohamae</Emphasis> from the masan bay,Korea

Increasing industrial development in the Masan Bay area of Korea over the past decades increased the risk for the survival of marine organisms in the bay area by the deterioration of the water quality. Since living organisms have the ability to adapt contamination-associated stimuli by the alteration of gene expression, changes in proteins can be used as an important criterion for assessing the levels of environmental conditions. In this study, therefore, alterations of the expression of proteins in the muscle ofLimanda yokohamae from Dukdong and Dotsum in the bay area were surveyed and characterized as compared with Haegumgang, which served as a control site. The results demonstrated that the twenty spots detected from Dukdong and Dotsum were similar to each other. Fifteen proteins were found to be predicted or undefined proteins, while five proteins were identified as heavy polypeptide 11 of myosin, apolipoprotein A-I, fibroblast growth factor 17b precursor, G protein-coupled receptor kinase 1 b and bonnie and clyde. These data suggest that local fish in the bay area have dysfunction in muscle physiology including contraction, lipid metabolism, proliferation and differentiation and nervous system.     

Nonlinear wave profiles of wave–wave interaction in a finite water depth by fixed point approach

In this paper, a superposition of two periodic wave profiles in a finite water depth was investigated. This paper is focused on the improvement of a wave profile on the linear superposition of two waves. This improvement was realized by introducing an iterative method, which was based on a fixed point approach. Application of the fixed point approach to the wave superposition made it possible to obtain a wave profile of wave–wave interaction. The improved result of the wave profile was in good agreement with that of the nonlinear perturbation solution of the second order. It was interesting that the improved result revealed the higher-order nonlinear frequencies for two interacting Stokes waves while Dalzell's solution by a perturbation method could not predict them.     

Nonlinear mooring line induced slow drift motion of an ALP-tanker

A tanker moored to an articulated loading platform (ALP) is modeled by a 2-DOF system. The mooring line between the ALP and tanker is represented by an unsymmetric, piecewise-nonlinear restoring function. Forced vibrations of this system are investigated using direct numerical integration. The highly nonlinear characteristics, including multiple solution, subharmonics, and bifurcations are discussed. Slow drift oscillation could occur under harmonic excitations due to nonlinearities of the systems. The sensitivity of the dynamic response of the strong nonlinear system with respect to system parameters and initial conditions is examined.