Diagnostic metrics for evaluation of annual and diurnal cycles   总被引：1，自引：0，他引：1  

Bin Wang  Hyung-Jin Kim  Kazuyoshi Kikuchi  Akio Kitoh 《Climate Dynamics》2011,37(5-6):941-955

Two sets of diagnostic metrics are proposed for evaluation of global models?? simulation of annual and diurnal cycles of precipitation. The metrics for the annual variation include the annual mean, the solstice and equinoctial asymmetric modes of the annual cycle (AC), and the global monsoon precipitation domain and intensity. The metrics for the diurnal variation include the diurnal range, the land?Csea contrast and transition modes of the diurnal cycle (DC), and the diurnal peak propagation in coastal regions. The proposed modes for the AC and DC represent faithfully the first two leading empirical orthogonal functions and explain, respectively, 82% of the total annual variance and 87% of the total diurnal variance over the globe between 45°S and 45°N. The simulated AC and DC by the 20-km-mesh MRI/JMA atmospheric general circulation model (AGCM) are in a wide-ranging agreement with observations; the model considerably outperforms any individual AMIP II GCMs and has comparable performance to 12-AMIP II model ensemble simulation measured by Pearson??s pattern correlation coefficient. Comparison of four versions of the MRI/JMA AGCM with increasing resolution (180, 120, 60, and 20?km) reveals that the 20-km version reproduces the most realistic annual and diurnal cycles. However, the improved performance is not a linear function of the resolution. Marked improvement of the simulated DC (AC) occurs at the resolution of 60?km (20?km). The results suggest that better represented parameterizations that are adequately tuned to increased resolutions may improve models?? simulation on the forced responses. The common deficiency in representing the monsoon domains suggests the models having difficulty in replicating annual march of the Subtropical Highs that is largely driven by prominent east-west land?Cocean thermal contrast. Note that the 20-km model reproduces realistic diurnal cycle, but fails to capture realistic Madden-Julian Oscillation.  相似文献   

Impact of vegetation feedback on the temperature and its diurnal range over the Northern Hemisphere during summer in a 2 × CO2 climate     

Su-Jong Jeong  Chang-Hoi Ho  Tae-Won Park  Jinwon Kim  Samuel Levis 《Climate Dynamics》2011,37(3-4):821-833

This study examines the potential impact of vegetation feedback on the changes in the diurnal temperature range (DTR) due to the doubling of atmospheric CO₂ concentrations during summer over the Northern Hemisphere using a global climate model equipped with a dynamic vegetation model. Results show that CO₂ doubling induces significant increases in the daily mean temperature and decreases in DTR regardless of the presence of the vegetation feedback effect. In the presence of vegetation feedback, increase in vegetation productivity related to warm and humid climate lead to (1) an increase in vegetation greenness in the mid-latitude and (2) a greening and the expansion of grasslands and boreal forests into the tundra region in the high latitudes. The greening via vegetation feedback induces contrasting effects on the temperature fields between the mid- and high-latitude regions. In the mid-latitudes, the greening further limits the increase in T _max more than T _min, resulting in further decreases in DTR because the greening amplifies evapotranspiration and thus cools daytime temperature. The greening in high-latitudes, however, it reinforces the warming by increasing T _max more than T _min to result in a further increase in DTR from the values obtained without vegetation feedback. This effect on T _max and DTR in the high latitude is mainly attributed to the reduction in surface albedo and the subsequent increase in the absorbed insolation. Present study indicates that vegetation feedback can alter the response of the temperature field to increases in CO₂ mainly by affecting the T _max and that its effect varies with the regional climate characteristics as a function of latitudes.  相似文献   

PAHs distribution in sediments associated with gas hydrate and oil seepage from the Gulf of Mexico     

Wang C  Sun H  Chang Y  Song Z  Qin X 《Marine pollution bulletin》2011,62(12):2714-2723

Six sediment samples collected from the Gulf of Mexico were analyzed. Total concentrations of the PAHs ranged from 52 to 403 ng g⁻¹ dry weight. The lowest PAH concentration without 5–6 rings PAHs appeared in S-1 sample associated with gas hydrate or gas venting. Moreover, S-1 sample had the lowest organic carbon content with 0.85% and highest reduced sulfur level with 1.21% relative to other samples. And, analysis of the sources of PAHs in S-1 sample indicated that both pyrogenic and petrogenic sources, converserly, while S-8, S-10 and S-11 sample suggested petrogenic origin. The distribution of dibenzothiophene, fluorine and dibenzofuran and the maturity parameters of triaromatic steranes suggested that organic matters in S-1 sample were different from that in S-8, S-10 and S-11 sample. This study suggested that organic geochemical data could help in distinguish the characteristic of sediment associated with gas hydrate or with oil seepage.  相似文献   

2011年3月24日缅甸孟帕亚M7.2级地震地震构造浅析   总被引：2，自引：1，他引：1  

常祖峰  安晓文  陈刚  陈宇军  余建强 《国际地震动态》2011,(4):52-56

本文简要论述了2011年3月24日缅甸孟帕亚M7.2级地震的发震构造,孟帕亚断裂的活动特征、活动时代,以及断裂与历史地震活动的关系.  相似文献   

区域断裂对韩国东南部地区现今应力状态的影响     

Chang C  Kang T S  李妍 《国际地震动态》2011,(1):98-103

利用朝鲜半岛东南部地区浅层地应力数据,给出区域现今应力状态的分布特征及其与断层分布的关系.地应力数据表明,区域最大主压应力呈ENE-WSW到NE-SW向,这与地震震源机制解及欧亚板块东部构造应力方向的一阶模式一致.或许是受到断层的影响,现今应力张量在大小和方向上表现出不均匀性.区域水平主应力变化较为一致,而垂向则变化较...  相似文献   

Evaluation of undrained shear strains in multi-directional horizontal shaking     

Wen-Jong Chang 《Soil Dynamics and Earthquake Engineering》2011

The evaluation of shear strains under multi-directional shaking is an important issue in interpreting dynamic soil behavior for both laboratory physical modeling and in situ monitoring. Shear strain components evaluated from Cartesian coordinates in undrained conditions have limitations to fully capture the coupled shear strain-pore pressure responses with an individual expression. In the present study, radial and rotational shear strain components derived from particle motions described with cylindrical polar coordinates are proposed. The proposed radial and rotational shear strains are verified with data from a bi-directional laminar shear box and a free field downhole array. Comparison results show that the proposed expressions of shear strain effectively capture the coupled strain-pore pressure responses in terms of the frequency content, amplitude variation, phase difference, and oscillation behavior. Comparison results reveal that the radial shear strain is the dominant shearing mode and the amplitude of the rotational shear strain is only 6.5–14.5% of the radial component. This provides quantitative data for the correction factor for multi-directional shaking and suggests that a simple shear system capable of inducing the radial shear strain on the vertical plane is a better approach than other shearing modes for physically modeling the behavior of soil subjected to undrained seismic loadings.  相似文献   

广西钦甲花岗岩体单颗粒锆石LA-ICP-MS U-Pb定年及其地质意义   总被引：10，自引：0，他引：10  

王永磊  王登红  张长青  侯可军  王成辉 《地质学报》2011,85(4):475-481

本文对钦甲花岗岩体进行了详细的LA-ICP-MS锆石U-Pb同位素年龄测定.这些锆石的阴极发光图像发育环带结构,Th/U值较高(大于0.1),具有岩浆成因锆石的特征.研究结果表明,钦甲花岗岩体为一复式岩体,其不同单元锆石的206Pb/238U加权平均年龄分别为412.4±1.8 Ma、434.8±1.7 Ma、442....  相似文献   

钢筋混凝土框架结构耗能分析     

叶献国  许政  常磊 《震灾防御技术》2011,6(4):448-453

本文从能量的观点,利用CANNY程序对普通钢筋混凝土框架结构进行了分析.通过对3种不同框架结构在不同地震动(31条)输入下的能量反应分析,研究了滞回耗能及阻尼耗能与总输入能的关系.针对本文模型的计算结果,给出了滞回耗能与总输入能关系的表达式,并初步探讨了其影响系数.研究表明,滞回耗能及阻尼耗能与总输入能之间有良好的线性关系.  相似文献   

Comment on ‘Causes,consequences and chronology of large‐magnitude palaeoflows in Middle and Late Pleistocene river systems of northwest Europe’ by Westaway and Bridgland (2010)     

Freek S. Busschers  Kim M. Cohen  Jef Vandenberghe  Ronald T. Van Balen  Cornelis Kasse  Jakob Wallinga  Henk J. T. Weerts 《地球表面变化过程与地形》2011,36(13):1836-1840

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Beta-�� distribution and its application to hydrologic events     

Md. Sharwar Murshed  Sangil Kim  Jeong-Soo Park 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(7):897-911

The beta-κ distribution is a distinct case of the generalized beta distribution of the second kind. In previous studies, beta-p and beta-κ distributions have played important roles in representing extreme events, and thus, the present paper uses the beta-κ distribution. Further, this paper uses the method of moments and the method of L-moments to estimate the parameters from the beta-κ distribution, and to demonstrate the performance of the proposed model, the paper presents a simulation study using three estimation methods (including the maximum likelihood estimation method) and beta-κ and non beta-κ samples. In addition, this paper evaluates the performance of the beta-κ distribution by employing two widely used extreme value distributions (i.e., the GEV and Gumbel distributions) and two sets of actual data on extreme events.  相似文献