A novel index to evaluate discretization methods:A case study of flood susceptibility assessment based on random forest     

Xianzhe Tang  Takashi Machimura  Wei Liu  Jiufeng Li  Haoyuan Hong 《地学前缘(英文版)》2021,12(6):313-325

The selection of a suitable discretization method(DM)to discretize spatially continuous variables(SCVs)is critical in ML-based natural hazard susceptibility assessment.However,few studies start to consider the influence due to the selected DMs and how to efficiently select a suitable DM for each SCV.These issues were well addressed in this study.The information loss rate(ILR),an index based on the informa-tion entropy,seems can be used to select optimal DM for each SCV.However,the ILR fails to show the actual influence of discretization because such index only considers the total amount of information of the discretized variables departing from the original SCV.Facing this issue,we propose an index,infor-mation change rate(ICR),that focuses on the changed amount of information due to the discretization based on each cell,enabling the identification of the optimal DM.We develop a case study with Random Forest(training/testing ratio of 7:3)to assess flood susceptibility in Wanan County,China.The area under the curve-based and susceptibility maps-based approaches were presented to compare the ILR and ICR.The results show the ICR-based optimal DMs are more rational than the ILR-based ones in both cases.Moreover,we observed the ILR values are unnaturally small(＜1％),whereas the ICR values are obviously more in line with general recognition(usually 10％-30％).The above results all demonstrate the superiority of the ICR.We consider this study fills up the existing research gaps,improving the ML-based natural hazard susceptibility assessments.  相似文献   

Uncertainty of the Linear Trend in the Zonal SST Gradient Across the Equatorial Pacific Since 1881     

Chan Zhang  Youmin Tang  Jun Ying  Junde Li 《大气与海洋》2019,57(1):61-72

The change in the zonal sea surface temperature gradient (ZSSTG) across the equatorial Pacific plays an important role in the global climate system. However, there has not yet been a consensual conclusion about the changing ZSSTG at either a short-term (from 20 to 90 years) or a long-term time scale (longer than 90 years) in the literature. In this study, the uncertainty of the trend in ZSSTG for different sub-periods since 1881 was examined using four interpolated datasets and four un-interpolated datasets. It was found that the trend in ZSSTG on the short-term time scale could be significantly influenced by internal variability such as the El Niño–Southern Oscillation and the Pacific Decadal Oscillation. On the long-term time scale, the sign of the ZSSTG trend depends on the dataset used. In particular, it was not possible to draw a uniform conclusion about the secular trends in ZSSTG in recent history, given the high sensitivity of the ZSSTG trends to the period, dataset, and regions used to calculate the trends. Our results imply that it may not be possible to detect the response of ZSSTG to global warming until a longer data record becomes available in the future.  相似文献   

准噶尔盆地玛湖凹陷深层油气流体相态研究   总被引：1，自引：0，他引：1  

张鸾沣  雷德文  唐勇  阿布力米提  陈刚强  胡文瑄  曹剑 《地质学报》2015,89(5):957-969

准噶尔盆地玛湖凹陷深层(5000m)是我国深层油气勘探当前的一个热点风险领域。为给区域下步油气勘探提供参考,通过对区内烃源岩和油气进行系统的地质地球化学正演、反演对比综合研究,重点分析了油气流体相态。结果表明,研究区深层稳定发育石炭系—二叠系四套烃源岩,有机质丰度高,普遍达到中等—好质量,类型多种多样,既可生油亦可生气,加之所有烃源岩均已基本进入高—过成熟演化,因此深层油气流体相态总体应高熟轻质,可能包括高熟轻质油、干酪根裂解气、油裂解气等。原油地球化学研究表明,原油随埋藏深度增加、层位变老,油质有逐渐变轻的趋势,成熟度有逐渐增大的趋势,保存条件亦逐渐变好,因此预测深层原油油质更轻、成熟度更高、保存条件更好。天然气地球化学研究表明,中浅层天然气可能属于混合来源,包括干酪根裂解气和油裂解气,规模性的高过成熟天然气可能在深层。因此,研究区深层油气资源丰富,相态轻质,成藏有利,值得勘探。这些认识还可供具有相似油气地质背景地区在研究和勘探时类比参考。  相似文献   

A modified genetic model for the Huangshandong magmatic sulfide deposit in the Central Asian Orogenic Belt,Xinjiang, western China   总被引：2，自引：0，他引：2  

Ya-Jing Mao  Ke-Zhang Qin  Chusi Li  Dong-Mei Tang 《Mineralium Deposita》2015,50(1):65-82

  相似文献   

强对流天气监测预报预警技术进展   总被引：23，自引：8，他引：15       下载免费PDF全文

郑永光  周康辉  盛杰  林隐静  田付友  唐文苑  蓝渝  朱文剑 《应用气象学报》2015,26(6):641-657

强对流天气预报业务包括监测、分析、预报、预警和检验等方面。对流初生识别、对流系统强度识别和对流天气类型识别等监测技术取得新进展,综合多源资料的监测技术已应用于中国气象局中央气象台业务。对流系统的触发、发展和维持机制等获得了新认识,我国不同类型强对流天气及其环境条件统计气候特征、分析规范及相应业务产品等为业务预报提供了必要基础和技术支撑。光流法、多尺度追踪技术以及应用模糊逻辑方法的临近预报技术等有明显进展,融合短时预报技术得到广泛应用,对流可分辨高分辨率数值 (集合) 预报及其后处理产品预报试验取得了显著成效,基于数值 (集合) 预报应用模糊逻辑方法的分类强对流天气短期预报技术为业务预报提供了技术支撑。强对流天气综合监测和多尺度自适应临近预报技术、多尺度分析技术以及融合短时预报技术、发展并应用模糊逻辑等方法的、基于高分辨率数值 (集合) 模式的区分不同强度等级和极端性的分类强对流天气精细化 (概率) 预报技术等是未来发展的主要方向。  相似文献   

基于模拟脚本的气象自动绘图系统   总被引：1，自引：0，他引：1  

杨波  朱文剑  唐文苑 《气象科技》2015,43(4):627-633

气象自动绘图系统（MEPAS）是一款紧贴我国业务数据环境,以MICAPS和GRIB1/GRIB2数据为主要输入源来实现自动化绘图的业务系统。MEPAS集成了多种物理量和对流参数的计算算法,在中尺度分析方面独具特色。MEPAS主要通过编写XML配置文件来模拟脚本,以命令行的方式运行,它学习简单,使用方便,运行稳定,出图高效,可用于业务系统的建设,也可用于气象科研,具有较高的应用推广价值。MEPAS通过模拟脚本实现自动绘图的技术可以被MICPAS借鉴或吸收,以填补MICAPS脚本交互的技术空白。  相似文献   

A brief introduction to BNU-HESM1.0 and its earth surface temperature simulations     

Shili Yang  Wenjie Dong  Jieming Chou  Jinming Feng  Xiaodong Yan  Zhigang Wei  Wenping Yuan  Yan Guo  Yanli Tang  Jiacong Hu 《大气科学进展》2015,32(12):1683-1688

Integrated assessment models and coupled earth system models both have their limitations in understanding the interactions between human activity and the physical earth system. In this paper,a new human–earth system model,BNUHESM1.0,constructed by combining the economic and climate damage components of the Dynamic Integrated Model of Climate Change and Economy to the BNU-ESM model,is introduced. The ability of BNU-HESM1.0 in simulating the global CO2 concentration and surface temperature is also evaluated. We find that,compared to observation,BNU-HESM1.0underestimates the global CO2 concentration and its rising trend during 1965–2005,due to the uncertainty in the economic components. However,the surface temperature simulated by BNU-HESM1.0 is much closer to observation,resulting from the overestimates of surface temperature by the original BNU-ESM model. The uncertainty of BNU-ESM falls within the range of present earth system uncertainty,so it is the economic and climate damage component of BNU-HESM1.0 that needs to be improved through further study. However,the main purpose of this paper is to introduce a new approach to investigate the complex relationship between human activity and the earth system. It is hoped that it will inspire further ideas that prove valuable in guiding human activities appropriate for a sustainable future climate.  相似文献   

ENSO-independent contemporaneous variations of anomalous circulations in the Northern and Southern Hemispheres: The polar-tropical seesaw mode     

唐卫亚  管兆勇 《Acta Meteorologica Sinica》2015,29(6):917-934

Using the NCEP/NCAR reanalysis and the ENSO indices from the Climate Prediction Center over the period 1978–2014, we have investigated the contemporaneous circulation variations in the Northern and Southern Hemispheres by performing the singular value decomposition analysis of sea level pressure anomalies (SLPA) after the ENSO signal is regressed out. It is found that there exists a polar-tropical seesaw mode (PTSM) that characterizes with the out of phase fluctuations of SLPA between the polar and tropical regions in the Northern and Southern Hemispheres in boreal winter. This PTSM explains 47.74% of the total covariance of SLPA and is almost independent of ENSO. It demonstrates a long-term trend and oscillation cycles of 2–3 and 4–6 yr. The long-term trend in PTSM indicates that the sea level pressure gradually decreases in the tropics and increases in the polar region with time. This PTSM looks roughly symmetric about the equator besides the seesaw pattern of SLPA between the tropics and polar region in each hemisphere. The disturbances in the geopotential height field in association with the PTSM shows baroclinic features in the tropics whereas equivalent barotropic features in the mid and high latitudes in the troposphere. The anomalous thermal forcing in the tropical region is possibly one of the factors facilitating the formation of this PTSM. Significant global precipitation and temperature anomalies related to the PTSM are observed. In the positive PTSM phase, precipitation and temperature are higher than normal in southern Europe and the Mediterranean and surrounding areas, but lower than normal in northern Europe and Siberia. Precipitation is higher than normal while temperature is lower than normal in Northeast Asia. Significant temperature and precipitation anomalies possibly occur in the regions of western China, northern India, parts of North America, parts of subtropical Africa, Maritime Continent, and Antarctic. These results are helpful for better understanding of the circulation variations and the mechanisms behind the interactions between the Northern and Southern Hemispheres and the related winter climate anomalies over globe.  相似文献   

The Austrian node of the natural resources satellite remote sensing cloud service platform:examples of Sino-Austrian cooperation     

Wolfgang Kainz  Xinming Tang  Yucai Xue 《地球空间信息科学学报》2021,24(1):145-151

The Austrian node of the Natural Resources Satellite Remote Sensing Cloud Service Platform was established in 2016 through a cooperation agreement between the Land Satellite Remote Sensing Application Center(LASAC),Ministry of Natural Resources of the Peoples Republic of China and the University of Vienna,Austria.Under this agreement panchromatic and multi-spectral data of the Chinese ZY-3 satellite are pushed to the server at the University of Vienna for use in education and research.So far,nearly 500 GB of data have been uploaded to the server.This technical note briefly introduces the ZY-3 system and illustrates the implementation of the agreement by the first China-Sat Workshop and several case studies.Some of them are already completed,others are still ongoing.They include a geometric accuracy validation of ZY-3 data,an animated visualization of image quick views on a spherical display to demonstrate the time series of the image coverage for Austria and Laos,and the use of ZY-3 data to study the spread of bark beetle in the province of Lower Austria.An accuracy study of DTMs from ZY-3 stereo data,as well as a land cover analysis and comparison of Austria with ZY-3 and other sensors are still ongoing.  相似文献   

中更新世以来西菲律宾海上层水体结构演化特征——来自钙质超微化石Florisphaera profunda的证据   总被引：1，自引：1，他引：0       下载免费PDF全文

孙晗杰  李铁刚  苏翔  孙荣涛  于心科  常凤鸣  唐正 《第四纪研究》2011,31(2):216-226

MD06-3050岩芯位于西非律宾海吕宋岛以东本哈姆高原,利用钙质超微化石下透光带种属Florisphaera profunda占总颗石的相对卡度,恢复了中更新世以来该海区的上层水体结构演化特征.结果显示,西菲律宾海区自1040ka以来,温跃层/营养跃层经历了由浅-深-浅-深的长周期变动.可能是由于全球碳库的长周期变化...  相似文献