Global parameter estimation of the Cochlodinium polykrikoides model using bioassay data     

CHO Hong-Yeon  PARK Kwang-Soon  KIM Sung 《海洋学报(英文版)》2016,35(2):39-45

Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of influence is very useful and important for the effective establishment of a reduction plan. In general, the information is supported by a red-tide(a.k.a algal bloom) model. The performance of the model is highly dependent on the accuracy of parameters, which are the coefficients of functions approximating the biological growth and loss patterns of the C. polykrikoides. These parameters have been estimated using the bioassay data composed of growth-limiting factor and net growth rate value pairs. In the case of the C. polykrikoides, the parameters are different from each other in accordance with the used data because the bioassay data are sufficient compared to the other algal species. The parameters estimated by one specific dataset can be viewed as locally-optimized because they are adjusted only by that dataset. In cases where the other one data set is used, the estimation error might be considerable. In this study, the parameters are estimated by all available data sets without the use of only one specific data set and thus can be considered globally optimized. The cost function for the optimization is defined as the integrated mean squared estimation error, i.e., the difference between the values of the experimental and estimated rates. Based on quantitative error analysis, the root-mean squared errors of the global parameters show smaller values, approximately 25%–50%, than the values of the local parameters. In addition, bias is removed completely in the case of the globally estimated parameters. The parameter sets can be used as the reference default values of a red-tide model because they are optimal and representative. However, additional tuning of the parameters using the in-situ monitoring data is highly required.As opposed to the bioassay data, it is necessary because the bioassay data have limitations in terms of the in-situ coastal conditions.  相似文献   

Cloud Radiative Effects and Changes Simulated by the Coupled Model Intercomparison Project Phase 5 Models     

Sun-Hee SHIN  Ok-Yeon KIM  Dongmin KIM  Myong-In LEE 《大气科学进展》2017,34(7):859-876

Using 32 CMIP5(Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects(CREs) in the historical run driven by observed external radiative forcing for 1850–2005, and their future changes in the RCP(Representative Concentration Pathway) 4.5 scenario runs for2006–2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics,four models—ACCESS1.0, ACCESS1.3, Had GEM2-CC, and Had GEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average.All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about-0.99% K~(-1)and net radiative warming of 0.46 W m~(-2)K~(-1), suggesting a role of positive feedback to global warming.  相似文献   

A New Infrared Atmospheric Sounding Interferometer Channel Selection and Assessment of Its Impact on Met Office NWP Forecasts     

Young-Chan NOH  Byung-Ju SOHN  Yoonjae KIM  Sangwon JOO  William BELL  Roger SAUNDERS 《大气科学进展》2017,34(11):1265-1281

A new set of Infrared Atmospheric Sounding Interferometer(IASI) channels was re-selected from 314 EUMETSAT channels.In selecting channels,we calculated the impact of the individually added channel on the improvement in the analysis outputs from a one-dimensional variational analysis(1D-Var) for the Unified Model(UM) data assimilation system at the Met Office,using the channel score index(CSI) as a figure of merit.Then,200 channels were selected in order by counting each individual channel's CSI contribution.Compared with the operationally used 183 channels for the UM at the Met Office,the new set shares 149 channels,while the other 51 channels are new.Also examined is the selection from the entropy reduction method with the same 1D-Var approach.Results suggest that channel selection can be made in a more objective fashion using the proposed CSI method.This is because the most important channels can be selected across the whole IASI observation spectrum.In the experimental trial runs using the UM global assimilation system,the new channels had an overall neutral impact in terms of improvement in forecasts,as compared with results from the operational channels.However,upper-tropospheric moist biases shown in the control run with operational channels were significantly reduced in the experimental trial with the newly selected channels.The reduction of moist biases was mainly due to the additional water vapor channels,which are sensitive to the upper-tropospheric water vapor.  相似文献   

Two Types of Diurnal Variations in Heavy Rainfall during July over Korea※     

Chang-Kyun PARK  Minhee CHANG  Chang-Hoi HO  Kyung-Ja HA  Jinwon KIM  Byung-Ju SOHN 《大气科学进展》2021,38(12):2201-2211

This study examined the characteristics of the diurnal variations of heavy rainfall (≥110 mm in 12 hours) in Korea and the related atmospheric circulation for July from 1980?2020. During the analysis period, two dominant pattens of diurnal variation of the heavy rainfall emerged: all-day heavy rainfall (AD) and morning only heavy rainfall (MO) types. For the AD-type, the heavy rainfall is caused by abundant moisture content in conjunction with active convection in the morning (0000?1200, LST; LST = UTC + 9) and the afternoon hours (1200?2400 LST). These systems are related to the enhanced moisture inflow and upward motion induced by the strengthening of the western North Pacific subtropical high and upper-tropospheric jet. For the MO-type, heavy rainfall occurs mostly in the morning hours; the associated atmospheric patterns are similar to the climatology. We find that the atmospheric pattern related to severe heavy rainfalls in 2020 corresponds to a typical AD-type and resembles the 1991 heavy-rainfall system in its overall synoptic/mesoscale circulations. The present results imply that extremely heavy rainfall episodes in Korea during the 2020 summer may occur again in the future associated with the recurring atmospheric phenomenon related to the heavy rainfall.  相似文献   

韩国济洲岛下西归浦组的时代及其古环境     

李保华  朴柄  金东升  吴相俊 《地层学杂志》2000,24(1):49-52

韩国济洲岛下西归浦组的时代归属一直存在着争论。该段地层中浮游有孔虫 Globigerina calida calida、Beella digitata、 Globigerina bermudezi和 Globoquadrina conglomerata的发现表明了它应为中更新世 (晚 N 2 2带、即 Globigerina calida calida亚带 ,不晚于 40万年前 )的沉积。底栖、浮游有孔虫的定量统计分析揭示了下西归浦组沉积环境的变化 :下部的沉积环境为岸外中陆架暖水 ,而向上则演变成近岸内陆架温凉水。有孔虫组合的更替反映了下西归浦组沉积是一个由次一级的 3个亚海退和 2个亚海进组成的海退序列。  相似文献   

安徽铜陵地区中酸性侵入岩及其岩石包体中的矿物包裹体研究   总被引：14，自引：2，他引：14  

田世洪  杜杨松  秦新龙  李铉具  金尚中  尹京武  李赞熙 《地学前缘》2001,8(4):422-428

铜陵地区是长江中、下游铁、铜、硫、金成矿带的重要组成部分。笔者对铜陵地区中酸性侵入岩及其岩石包体中的包裹体进行了较系统的岩相学、显微测温和激光拉曼光谱研究。通过岩相学观察发现了 3类包裹体 ,即晶质熔融包裹体、流体熔融包裹体和流体包裹体。显微测温资料表明 ,本区的岩浆流体成矿演化可分为 3个阶段 :岩浆阶段 ( >12 5 0～ 90 0℃± )、过渡岩浆阶段 ( 90 0～ 75 0℃± )和岩浆期后热液阶段 ( <75 0℃ )。部分熔浆的温度之高 (可达 12 5 0℃ ) ,表明其可能是底侵幔源岩浆同熔下地壳形成的。在老庙基岩体、小铜官山岩体、鸡冠石岩体和小陶家岩体中产有晶质熔融包裹体、流体熔融包裹体和流体包裹体这 3种包裹体 ,表明相应的岩浆流体演化具有连续性、继承性和阶段性 ,其对应的成矿溶液以岩浆热液为主 ;与此不同的是 ,在鸡冠山岩体和白芒山岩体中仅产有晶质熔融包裹体和流体包裹体两种类型的包裹体 ,表明相应的岩浆流体演化不具连续性 ,其对应的成矿溶液以天水热液为主。此外 ,在小铜官山岩体和鸡冠石岩体的中酸性侵入岩中 ,发现了不混溶包裹体 ,其可能是在压力释放条件下形成的。  相似文献   

EXPERIMENTAL EVIDENCE OF S*-WAVE*     

J.Y. KIM  J. BEHRENS 《Geophysical Prospecting》1986,34(1):100-108

During development of theoretical methods to compute synthetic seismograms, a new type of wave called S*-wave was discovered by Hron and Mikhailenko. This wave propagates with the shear-wave velocity and can be interpreted as a non-geometrical wave arrival with large amplitudes strongly depending on the depth of a pure P-point source. In this first experimental verification of the existence of S*-waves by means of two-dimensional model-seismics it is demonstrated that: 1. the S*-wave exists and depends on the source distance from the free surface; 2. the S*-wave is generated as an ordinary shear wave on the free surface at the point located directly above the P-source, as illustrated in the synthetic seismograms. The measured seismograms agree remarkably well with the computed ones.  相似文献   

材料复合桩的现场承载性能试验研究     

李宝建  李光范  胡伟  赵菲  金燦起 《岩土力学》2015,36(Z2):629-632

基于水平荷载作用下桩基的弯矩沿深度呈由上向下骤减的规律,将桩的上部设计为抗弯性能良好的钢管桩而下部为抗弯性能较弱的PHC桩,并选择适当的部位通过焊接等方式连接两种桩型。在现场进行锤击试验、水平承载力试验和连接部位抗弯性能试验,将复合桩的压应力、拉应力和水平承载力与材料允许值对比比较。结果表明,所选择的材料复合型桩充分发挥了材料性能,尤其在水平承载力方面表现突出,且不同材料桩型连接部位性能良好。试验结果为桩基的改进提供了新思路和试验依据。  相似文献   

Effects of a Building＇s Density on Flow in Urban Areas     

Jae-Jin KIM Do-Yong KIM 《大气科学进展》2009,(1)

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Radar Data Assimilation for the Simulation of Mesoscale Convective Systems     

Jo-Han LEE  Dong-Kyou LEE  Hyun-Ha LEE  Yonghan CHOI  Hyung-Woo KIM 《大气科学进展》2010,27(5):1025-1042

A heavy rainfall case related to Mesoscale Convective Systems (MCSs) over the Korean Peninsula was selected to investigate the impact of radar data assimilation on a heavy rainfall forecast. The Weather Research and Forecasting (WRF) three-dimensional variational (3DVAR) data assimilation system with tuning of the length scale of the background error covariance and observation error parameters was used to assimilate radar radial velocity and reflectivity data. The radar data used in the assimilation experiments were preprocessed using quality-control procedures and interpolated/thinned into Cartesian coordinates by the SPRINT/CEDRIC packages. Sensitivity experiments were carried out in order to determine the optimal values of the assimilation window length and the update frequency used for the rapid update cycle and incremental analysis update experiments. The assimilation of radar data has a positive influence on the heavy rainfall forecast. Quantitative features of the heavy rainfall case, such as the maximum rainfall amount and Root Mean Squared Differences (RMSDs) of zonal/meridional wind components, were improved by tuning of the length scale and observation error parameters. Qualitative features of the case, such as the maximum rainfall position and time series of hourly rainfall, were enhanced by an incremental analysis update technique. The positive effects of the radar data assimilation and the tuning of the length scale and observation error parameters were clearly shown by the 3DVAR increment.  相似文献