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排序方式: 共有249条查询结果,搜索用时 15 毫秒
81.
Byung-Kwon Moon Daeok Youn Rokjin J. Park Sang-Wook Yeh Won-Mo Kim Young-Ho Kim Jaein I. Jeong Jung-Hun Woo Eul Gyu Im Chang-Keun Song 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(4):345-351
We examine the meteorological responses due to the probable eruption of Mt. Baekdu using an off-line Climate-Chemistry model that is composed of the National Center for Atmospheric Research (NCAR) Climate Atmosphere Model version 3 (CAM3) and a global chemistry transport model (GEOS-Chem). Using the aerosol dataset from the GEOS-Chem driven by GEOS-5 meteorology, experiment and control simulations of the climate model are performed and their meteorological differences between the two simulations are analyzed. The magnitudes of volcanic eruption and column injection height were presumably set to 1/200 of the Mt. Pinatubo eruption and 9 km, respectively. Significant temperature drop in the lower troposphere (850 hPa), which is mainly due to a direct effect of prescribed volcanic aerosols from Mt. Baekdu, has been simulated up to about ?4 K. The upper atmosphere (150 hPa) right above the volcano, however, shows significant warming due to the absorption of the infrared radiation by volcanic aerosols. As a result of the volcanic eruption in the climate model, wave-like patterns are shown in both the geopotential height and horizontal wind. The changes in the lower atmospheric temperature are well associated with the modification of the atmospheric circulation through the hydrostatic balance. In spite of limitations in our current simulations due to several underlying assumptions, our results could give a clue to understanding the meteorological impacts from Mt. Baekdu eruptions that are currently attracting considerable public attention. 相似文献
82.
83.
In-Hyuk Kwon Hyo-Jong Song Ji-Hyun Ha Hyoung-Wook Chun Jeon-Ho Kang Sihye Lee Sujeong Lim Youngsoon Jo Hyun-Jun Han Hanbyeol Jeong Hui-Nae Kwon Seoleun Shin Tae-Hun Kim 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(1):319-335
This study introduces the operational data assimilation (DA) system at the Korea Institute of Atmospheric Prediction Systems (KIAPS) to the numerical weather prediction community. Its development history and performance are addressed with experimental illustrations and the authors’ previously published studies. Milestones in skill improvements include the initial operational implementation of three-dimensional variational data assimilation (3DVar), the ingestion of additional satellite observations, and changing the DA scheme to a hybrid four-dimensional ensemble-variational DA using forecasts from an ensemble based on the local ensemble transform Kalman filter (LETKF). In the hybrid system, determining the relative contribution of the ensemble-based covariance to the resultant analysis is crucial, particularly for moisture variables including a variety of horizontal scale spectra. Modifications to the humidity control variable, partial rather than full recentering of the ensemble for humidity further improves moisture analysis, and the inclusion of more radiance observations with higher-level peaking channels have significant impacts on stratosphere temperature and wind performance. Recent update of the operational hybrid DA system relative to the previous 3DVar system is described for detailed improvements with interpretation. 相似文献
84.
Trilobite Biostratigraphy of the lower Paleozoic (Cambrian–Ordovician) Joseon Supergroup, Taebaeksan Basin, Korea 总被引:1,自引:0,他引:1
CHOI Duck K. LEE Jeong Gu LEE Seung-Bae PARK Tae-Yoon S. HONG Paul S. 《《地质学报》英文版》2016,90(6):1976-1999
In Korea,trilobites are among the most intensively studied fossil groups in the past century and provide invaluable information about lower Paleozoic stratigraphy,paleogeography,and tectonics of the Korean Peninsula. Trilobites occur in the lower Paleozoic Joseon Supergroup of the Taebaeksan Basin which was part of the Sino-Korean Craton in the Paleozoic. The Joseon Supergroup is divided into the Taebaek,Yeongwol,and Mungyeong groups. The Taebaek and Yeongwol groups are richly fossiliferous,while the Mungyeong Group is poorly fossiliferous. Contrasting trilobite faunal contents of the Taebaek and Yeongwol groups resulted in two separate biostratigraphic schemes for the Cambrian–Ordovician of the Taebaeksan Basin. A total of 22 biozones or fossiliferous horizons were recognized in the Taebaek Group; 19 zones were established in the Yeongwol Group; and four biozones were known from the Mungyeong Group. These trilobite biozones of the Taebaeksan Basin indicate the Joseon Supergroup ranges in age from the Cambrian Series 2 to Middle Ordovician and can be correlated well with the formations of North China,South China,and Australia. 相似文献
85.
Iron sulfide was synthesized by reacting aqueous solutions of sodium sulfide and ferrous chloride for 3 days. By X-ray powder diffraction (XRPD), the resultant phase was determined to be primarily nanocrystalline mackinawite (space group: P4/ nmm) with unit cell parameters a = b = 3.67 Å and c = 5.20 Å. Iron K-edge XAS analysis also indicated the dominance of mackinawite. Lattice expansion of synthetic mackinawite was observed along the c-axis relative to well-crystalline mackinawite. Compared with relatively short-aged phase, the mackinawite prepared here was composed of larger crystallites with less elongated lattice spacings. The direct observation of lattice fringes by HR-TEM verified the applicability of Bragg diffraction in determining the lattice parameters of nanocrystalline mackinawite from XRPD patterns. Estimated particle size and external specific surface area (SSAext) of nanocrystalline mackinawite varied significantly with the methods used. The use of Scherrer equation for measuring crystallite size based on XRPD patterns is limited by uncertainty of the Scherrer constant (K) due to the presence of polydisperse particles. The presence of polycrystalline particles may also lead to inaccurate particle size estimation by Scherrer equation, given that crystallite and particle sizes are not equivalent. The TEM observation yielded the smallest SSAext of 103 m2/g. This measurement was not representative of dispersed particles due to particle aggregation from drying during sample preparation. In contrast, EGME method and PCS measurement yielded higher SSAext (276-345 m2/g by EGME and 424 ± 130 m2/g by PCS). These were in reasonable agreement with those previously measured by the methods insensitive to particle aggregation. 相似文献
86.
Growth,feeding and ecological roles of the mixotrophic and heterotrophic dinoflagellates in marine planktonic food webs 总被引:4,自引:0,他引:4
Hae Jin Jeong Yeong Du Yoo Jae Seong Kim Kyeong Ah Seong Nam Seon Kang Tae Hoon Kim 《Ocean Science Journal》2010,45(2):65-91
Planktonic mixotrophic and heterotrophic dinoflagellates are ubiquitous protists and often abundant in marine environments. Recently many phototrophic dinoflagellate species have been revealed to be mixotrophic organisms and also it is suggested that most dinoflagellates may be mixotrophic or heterotrophic protists. The mixotrophic and heterotrophic dinoflagellates are able to feed on diverse prey items including bacteria, picoeukaryotes, nanoflagellates, diatoms, other dinoflagellates, heterotrophic protists, and metazoans due to their diverse feeding mechanisms. In turn they are ingested by many kinds of predators. Thus, the roles of the dinoflagellates in marine planktonic food webs are very diverse. The present paper reviewed the kind of prey which mixotrophic and heterotrophic dinoflagellates are able to feed on, feeding mechanisms, growth and ingestion rates of dinoflagellates, grazing impact by dinoflagellate predators on natural prey populations, predators on dinoflagellates, and red tides dominated by dinoflagellates. Based on this information, we suggested a new marine planktonic food web focusing on mixotrophic and heterotrophic dinoflagellates and provided an insight on the roles of dinoflagellates in the food web. 相似文献
87.
88.
西南极利文斯顿岛百耳斯半岛中生代火山岩地球化学特征 总被引:1,自引:0,他引:1
西南极利文斯顿岛百耳斯半岛中生代火山岩是晚侏罗纪至晚白垩纪三期火山活动的产物。岩石普遍贫钾,轻稀土元素略为富集,但轻重稀土分馏不强烈;Sr、K、Rb、Ba、Th等大离子亲石元素(LIL)明显富集,Nb和Ta明显亏损,过渡金属族元素Cr和Ni强烈亏损,表明它们属于火山弧环境中生成的钙碱性系列岩石。白垩纪中期和白垩纪晚期岩石的87Sr/86Sr比值主要在0.7039~0.7053之间变化,εNd>0,87Sr/86Sr相对1/Sr、Rb、K和SiO2等的变化不大,表明其源区岩浆可能直接来自上地幔,很少受到壳源物质的混染。而晚侏罗纪火山岩的Sr同位素比值较高,说明早期岩浆可能受到少量地壳物质的混染。但在Th/Ta-Th和Th/Sm-Th图解上所有岩石的投影点分布趋势相同,趋势线的斜率>0。百耳斯半岛中生代火山岩是上地幔部分熔融生成的同源岩浆不同期的产物 相似文献
89.
Cheongho Han & Youngjin Jeong 《Monthly notices of the Royal Astronomical Society》1998,301(1):231-234
Despite the same multiplicity of lenses and sources, the frequency of detection of binary source events is relatively very low compared with that of binary lens events. Dominik pointed out that the rarity of binary source events is caused mainly by the large difference in amplification between the component stars. In this paper, we determine that the fraction of events with similar source star amplifications is as large as ∼8 per cent, and thus show that the very low detection rate for binary source events cannot be explained by this effect alone. By carrying out realistic simulations of binary source events, we find that a significant number of binary source events are additionally missed from detection for various other reasons. First, if the flux ratio between the component stars is very large, the light curve of the bright star is hardly affected by the light from the faint star. Secondly, if the separation is too small, the binary source stars behave like a single star, making it difficult to separate the binary source event from a single source event. Finally, although the probability of detecting binary source events increases as the source separation increases, some fraction of binary source events will still be missed because the light curves of these events will mimic those of single source events with longer time-scales and larger values of the impact parameter. 相似文献
90.
Jin Koo Kim Jeong -Ho Park Jung Hwa Choi Kwang Ho Choi Yeong Min Choi Dae Soo Chang Young Seop Kim 《Ocean Science Journal》2007,42(2):61-67
Three barracudina fishes (Paralepididae) were newly recorded from the southern sea of Korea. Lestidium prolixum is characterized
by a single band of luminous ducts on the midventral line and absence of a papilla anterior to the eye. Lestrolepis intermedia
and L. japonica are similar in having a black papilla immediately in front of the eye and two bands of luminous ducts on the
midventral line. However, the dorsal fin of L. intermedia is located more posterior along the body than that of L. japonica,
and L. intermedia have larger number of anal fin rays 42 (vs. 36–40) and vertebrae 95 (vs. 86–87) than L. japonica. 相似文献