Possible influence of South Asian high on summer rainfall variability in Korea     

Ki-Seon Choi  Baek-Jo Kim  Renhe Zhang  Jae-Cheol Nam  Ki-Jun Park  Jeoung-Yun Kim  Do-Woo Kim 《Climate Dynamics》2016,46(3-4):833-846

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日本海西南陆坡全新世对马暖流演化的沉积学和地球化学记录     

徐兆凯  崔镇勇  林东日  李铁刚  李安春 《海洋地质与第四纪地质》2010,(1)

对日本海西南陆坡对马暖流主流轴下方高沉积速率沉积物柱状样,进行了沉积学和地球化学系统研究,以探讨全新世以来对马暖流在研究区的形成与演化,并得出了与附近地区古海洋学方法非常相近的结果,从而为今后研究区的对马暖流演化研究提供了沉积学和地球化学指标。据此,该柱状样中所记录的对马暖流演化可划分为5个主要阶段。全新世初期(9.6kaBP),对马暖流开始进入日本海,其强度较弱,同时,伴随着富营养东海沿岸水的影响,海底环境由还原性向氧化性转变;6.5kaBP时,对马暖流控制下的日本海南部现代对流模式最终建立起来,东海沿岸水的影响基本消失,随后,对马暖流明显减弱;3.0kaBP时,对马暖流再次增强并基本达到现在水平,且在随后的3ka里保持总体稳定,期间在2.0～0.7kaBP存在一次较弱的减弱过程。  相似文献   

Analysis of anthropogenic CO₂ signal in ICARTT using a regional chemical transport model and observed tracers     

J. E. CAMPBELL  G. R. CARMICHAEL  Y. TANG  T. CHAI  S. A. VAY  Y.-H. CHOI  G. W. SACHSE  H. B. SINGH  J. L. SCHNOOR  J. WOO  J. M. VUKOVICH  D. G. STREETS  L. G. HUEY  C. O. STANIER 《Tellus. Series B, Chemical and physical meteorology》2007,59(2):199-210

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Simulation of the extreme waves generated by typhoon Bolaven (1215) in the East China Sea and Yellow Sea     

JUN Ki Cheon  JEONG Weon Mu  CHOI Jin Yong  PARK Kwang Soon  JUNG Kyung Tae  KIM Mee Kyung  CHAE Jang Won  QIAO Fangli 《海洋学报(英文版)》2015,34(12):19-28

Record-breaking high waves occurred during the passage of the typhoon Bolaven (1215) (TYB) in the East China Sea (ECS) and Yellow Sea (YS) although its intensity did not reach the level of a super typhoon. Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys. In order to understand how such high waves with long duration occurred, analyses have been made through measurement and numerical simulations. TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements. And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model. Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area. Thus the accuracy of simulations is considerably enhanced, and the computed results are also in better agreement with measured data than before. It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track. As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days, the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.  相似文献   

Interdecadal changes in summer TC activity in East China Sea     

Ki-Seon Choi  Yu-Mi Cha  Sung-Dae Kang  Hae-Dong Kim 《Theoretical and Applied Climatology》2015,120(1-2):11-18

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Development of a skill assessment tool for the Korea operational oceanographic system   总被引：1，自引：1，他引：0  

CHO Kyoung-Ho  CHOI Jin-Yong  JEONG Sang-Hun  CHOI Jung-Woon  KWON Jae-Il  PARK Kwang-Soon 《海洋学报(英文版)》2013,32(9):74-81

A standard skill assessment(SA) tool was developed and implemented to evaluate the performance of operational forecast models in the Korea operational oceanographic system.The SA tool provided a robust way to assess model skill in the system by comparing predictions and observations,and involved the computation of multiple skill metrics including correlation and error skills.User-and system-based acceptance criteria of skill metrics were applied to determine whether predictions were acceptable for the system.To achieve this,the tool produced a time series comparison plot,a skill score table,and an advanced summarized diagram to effectively demonstrate the multiple skill scores.Moreover,the SA was conducted to evaluate both atmospheric and hydrodynamic forecast variables.For the atmospheric variables,acceptable error criteria were preferable to acceptable correlation criteria over short timescales,since the mean square error overwhelmed the observation variance.Conversely,for the hydrodynamic variables,acceptable root mean square percentage error(e.g.,p erms) criteria were preferable to acceptable error(e.g.,erms) criteria owing to the spatially variable tidal intensity around the Korean Peninsula.Furthermore,the SA indicated that predetermined acceptance error criteria were appropriate to satisfy a target central frequency(fc) for which errors fell within the specified limits(i.e.,the fc equals 70%).  相似文献   

Seasonal prediction for tropical cyclone frequency around Taiwan using teleconnection patterns     

Ki-Seon Choi  Chun-Chieh Wu  Yuqing Wang 《Theoretical and Applied Climatology》2014,116(3-4):501-514

In this study, a statistical model is developed to predict the frequency of tropical cyclones (TCs) that influence Taiwan in boreal summer. Predictors are derived from large-scale environments from February to May in six regions, including four atmospheric circulation predictors over the western sea and eastern sea of Australia, the subtropical western North Pacific (SWNP), and the eastern sea of North America, and two sea surface temperature predictors in the Southeast Indian Ocean and the North Atlantic. The statistical model is verified based on statistical cross-validation tests and by contrasting the differences in the large-scale environments between high and low TC frequency years hindcasted by the model. The results show the relationships of two atmospheric circulation predictors and one SST predictor around Australia with Antarctic Oscillation (AAO) pattern, as well as the relationships of those in the SWNP and around eastern sea of North America with Pacific/North American teleconnection (PNA) pattern. When the anomalous anticyclone around Australia (positive AAO pattern) and the one over the region from eastern sea of North America and the Aleutian Islands to the SWNP (negative PNA pattern) are both strengthened from February, the trade wind in the equatorial Pacific is intensified and consequently plays an important role in steering TCs towards Taiwan during boreal summer.  相似文献   

Possible relationship between North Korean total rainfall and Arctic Oscillation in May     

Ki-Seon Choi  Sung-Dae Kang  Hae-Dong Kim 《Theoretical and Applied Climatology》2013,112(3-4):483-494

In this study, a negative correlation between the rainfall over North Korea in May and the Arctic Oscillation (AO) in the same month is analyzed. The reasons for rainfall declines in the positive AO phase are as follows: (a) the strengthening of anomalous anticyclone in the Maritime Province of Siberia, (b) the weakening of the subtropical western North Pacific high, and (c) the stabilization across all the atmospheric layers in North Korea. Anomalous anticyclone strengthened in the Maritime Province of Siberia plays a critical role in placing the North Korean region under the influence of anomalous northeasterlies. In addition, the development of the anomalous northeasterlies results in the supply of a large amount of cold and dry air into North Korea. This consequently stabilizes the atmosphere in North Korea. Moreover, the reinforcement of anomalous cold sea surface temperature in the mid-latitude region of East Asia is found to be another reason for the atmospheric stabilization.  相似文献   

Interdecadal change in North Korean winter mean rainfall     

Ki-Seon Choi  Sung-Dae Kang  Hae-Dong Kim 《Theoretical and Applied Climatology》2013,114(1-2):169-182

In the present study, it was found that there was a significant climate regime shift in 1993 from average rainfall amounts in winter (December of a year and January and February of the next year) in North Korea over the last 30 years (1982–2011). This significant climate regime shift in 1993 also appeared in empirical orthogonal function analysis conducted using the winter mean rainfall amounts observed at 26 weather observation stations in North Korea. The reason why winter mean rainfall amounts in North Korea were smaller during the period of 1994–2011 than during the period of 1982–1994 was that anomalous anticyclone was reinforced in regions near Lake Baikal while anomalous cyclone was reinforced on the sea on the east of Japan so that the winter pressure system pattern (west high-east low pattern) appeared and thus anomalous cold and dry northerlies were reinforced in most East Asian regions including North Korea. To figure out the reason why anomalous anticyclone was reinforced further in the East Asian continent in winters during the period of 1994–2011, differences in water equivalent of accumulated snow depths between the two periods were analyzed. As a result, more snow was observed in most East Asian regions during the period of 1994–2011. Therefore, anomalous anticyclone could be further reinforced in the East Asian continent because surface air temperature dropped further due to snow-albedo effect. The surface air temperature cooling deepened further in the East Asian continent during the period of 1994–2011 due to snow-albedo effect was identified through differences in sensible heat net flux between the two periods.  相似文献   

Clastic matrix in EH3 chondrites     

Alan E. RUBIN  Christian D. GRISET  Byeon‐Gak CHOI  John T. WASSON 《Meteoritics & planetary science》2009,44(4):589-601

Abstract— Patches of clastic matrix (15 to 730 μm in size) constitute 4.9 vol% of EH3 Yamato (Y‐) 691 and 11.7 vol% of EH3 Allan Hills (ALH) 81189. Individual patches in Y‐691 consist of 1) ?25 vol% relatively coarse opaque grain fragments and polycrystalline assemblages of kamacite, schreibersite, perryite, troilite (some grains with daubréelite exsolution lamellae), niningerite, oldhamite, and caswellsilverite; 2) ?30 vol% relatively coarse silicate grains including enstatite, albitic plagioclase, silica and diopside; and 3) an inferred fine nebular component (?45 vol%) comprised of submicrometer‐size grains. Clastic matrix patches in ALH 81189 contain relatively coarse grains of opaques (?20 vol%; kamacite, schreibersite, perryite and troilite) and silicates (?30 vol%; enstatite, silica and forsterite) as well as an inferred fine nebular component (?50 vol%). The O‐isotopic composition of clastic matrix in Y‐691 is indistinguishable from that of olivine and pyroxene grains in adjacent chondrules; both sets of objects lie on the terrestrial mass‐fractionation line on the standard three‐isotope graph. Some patches of fine‐grained matrix in Y‐691 have distinguishable bulk concentrations of Na and K, inferred to be inherited from the solar nebula. Some patches in ALH 81189 differ in their bulk concentrations of Ca, Cr, Mn, and Ni. The average compositions of matrix material in Y‐691 and ALH 81189 are similar but not identical‐matrix in ALH 81189 is much richer in Mn (0.23 ± 0.05 versus 0.07 ± 0.02 wt%) and appreciably richer in Ni (0.36 ± 0.10 versus 0.18 ± 0.05 wt%) than matrix in Y‐691. Each of the two whole‐rocks exhibits a petrofabric, probably produced by shock processes on their parent asteroid.  相似文献