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811.
Two piston cores (DD09-ST21, DD09-ST39B) from the northeastern Ulleung Basin in the East Sea were obtained to investigate variations in the biogenic components (calcium carbonate, organic carbon) and biogeochemical processes (δ13C and δ15N). The two cores had distinctive characteristics in terms of surface production, preservation and dissolution capacity of carbonate, and redox conditions of bottom-water. Core DD09-ST21 was characterized by an oxygen-depleted condition from 15 ka (MIS 2) to 60 ka (MIS 3). Core DD09-ST39B, on the other hand, showed oxic bottom-water conditions, possibly due to shallow water depth. These two cores with different redox condition showed opposite trends in terms of CaCO3, TOC, and C37 alkenone concentrations. CaCO3 and C37 concentrations were higher during the LGM in DD09-ST21 while lower contents were observed in DD09-ST39B in the same period. Moreover, consistently low TOC in DD09-ST39B and higher fluctuation of organic matters in DD09-ST21 may suggest difference in primary productivity, preservation capacity, or a potential dissolution effect. During the Holocene, the surface productivity of both cores increased, probably due to renewed ventilation and vertical mixing in the East Sea. Therefore, this study suggests spatial variation in production and preservation of biogenic components in the two cores since last 50 ka for DD09-ST39B and 80 ka for DD09-ST21 due to difference in environmental conditions such as water depth, bottom-water conditions, surface productivity and preservation. 相似文献
812.
Eko Setyobudi Chan-Hyeok Jeon Kwangho Choi Sung Il Lee Chung Il Lee Jeong-Ho Kim 《Ocean Science Journal》2013,48(2):197-205
The occurrence of Genus Anisakis nematode larvae in marine fishes and cephalopods is epidemiologically important because Anisakis simplex larval stage can cause a clinical disease in humans when infected hosts are consumed raw. Common squid (Todarodes pacificus) from Korean waters were investigated for anisakid nematodes infection during 2009~2011. In total, 1,556 larvae were collected from 615 common squids and 732 of them were subsequently identified by PCR-RFLP analysis of ITS rDNA. Depending on the sampling locations, the nematode larvae from common squid showed different prevalence, intensity and species distribution. A high prevalence (P) and mean intensity (MI) of infection were observed in the Yellow Sea (n = 250, P = 86.0%, MI = 5.99 larvae/host) and the southern sea of Korea (n = 126, P = 57.1%, MI = 3.36 larvae/host). Anisakis pegreffii was dominantly found in common squid from the southern sea (127/ 140, 90.7%) and the Yellow Sea (561/565, 98.9%). In contrast, the P and MI of infection were relatively low in the East Sea (n = 239, P = 8.37%, MI = 1.25 larvae/host). A. pegreffii was not found from the East Sea and 52.0% (13/25) of the nematodes were identified as A. simplex. Most of them were found in the body cavity or digestive tract of common squid, which are rarely consumed raw by humans. Considering the differenences in anisakid nematode species distribution and their microhabitat in common squid, it remains unclear whether common squid plays an important role in the epidemiology of human anisakis infection in Korea. Further extensive identification of anisakid nematodes in common squid, with geographical and seasonal information will be necessary. 相似文献
813.
Hyun Hee Kim Seon Ki Park Dusanka Zupanski Milija Zupanski 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(3):317-325
In this study, the maximum likelihood ensemble filter (MLEF) is applied to a tropical cyclone case to identify the uncertainty areas in the context of targeting observations, using the WRF model. Typhoon Sinlaku (2008), from which dropwindsonde data are collected through THORPEX Pacific Asian Regional Campaign (TPARC), is selected for the case study. For the uncertainty analysis, a measurement called the deep layer mean (DLM) wind variance is employed. With assimilation of conventional rawinsonde data, the MLEF-WRF system demonstrated stable data assimilation performance over multiple data assimilation cycles and produced high uncertainties mostly in data-void areas, for the given tropical cyclone case. Dropwindsonde deployment through T-PARC turned out to occur inside or near the weak uncertainty areas that are identified through the MLEF-WRF system. The uncertainty analysis using the MLEF method can provide a guide for identifying more effective targeting observation areas. 相似文献
814.
Byoung-Joo Jung Hyun Mee Kim Yeon-Hee Kim Eun-Hee Jeon Ki-Hoon Kim 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(3):305-316
In this study, the impact of various types of observations on the track forecast of Tropical Cyclone (TC) Jangmi (200815) is examined by using the Weather Research and Forecasting (WRF) model and the corresponding three-dimensional variational (3DVAR) data assimilation system. TC Jangmi is a recurving typhoon that is observed as part of the THORPEX Pacific Asian Regional Campaign (T-PARC). Conventional observations from the Korea Meteorological Administration (KMA) and targeted dropsonde observations from the Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR) were used for a series of observation system experiments (OSEs). We found that the assimilation of observations in oceanic areas is important to analyze environmental flows (such as the North Pacific high) and to predict the recurvature of TC Jangmi. The assimilation of targeted dropsonde observations (DROP) results in a significant impact on the track forecast. Observations of ocean surface winds (QSCAT) and satellite temperature soundings (SATEM) also contribute positively to the track forecast, especially two- to three-day forecasts. The impact of sensitivity guidance such as real-time singular vectors (SVs) was evaluated in additional experiments. 相似文献
815.
Kyu Rang KIM Tae Heon KWON Yeon-Hee KIM Hae-Jung KOO Byoung-Cheol CHOI Chee-Young CHOI 《大气科学进展》2009,26(2):283-292
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
0.13oC 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. 相似文献
816.
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.
相似文献
In-Sik KangEmail: |
817.
818.
819.
Geothermal gradient of the upper mantle beneath Jeju Island, Korea: Evidence from mantle xenoliths 总被引:2,自引:0,他引:2
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-Al2 O3 -SiO2 -Cr2 O3 (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. 相似文献
820.
Jo Hyun Kyoung Sa Young Hong Jang Whan Kim Kwang June Bai 《Ocean Engineering》2005,32(17-18):2020-2039
A nonlinear sloshing problem is numerically simulated. During excessive sloshing, the sloshing-induced impact load can cause a critical damage on the tank structure. Recently the problem becomes an important research topic in LNG (Liquefied Natural Gas) Tanker and FPSO (Floating Production Storage Offloading) design. In this study, the wave impact load on the structure is obtained numerically by imposing the exact nonlinear free surface conditions and compared with that predicted by Morison's formula. As a theoretical model, a three-dimensional free surface flow in a tank is formulated in the scope of potential flow theory with the exact nonlinear free-surface conditions. A finite-element method based on Hamilton's principle is employed as a numerical method. The problem is treated as an initial-value problem. The nonlinear problem is numerically solved through an iterative scheme at each time step. 相似文献