Climatology of Tropical Cyclone Extreme Rainfall over China from 1960 to 2019     

Ying LI  Dajun ZHAO 《大气科学进展》2022,39(2):320-332

Tropical cyclone extreme rainfall(TCER)causes devastating floods and severe damage in China and it is therefore important to determine its long-term climatological distribution for both disaster prevention and operational forecasting.Based on the tropical cyclone(TC)best-track dataset and TC precipitation data from 1960 to 2019,the spatiotemporal distribution of TCER affecting China is analyzed.Results show that there were large regional differences in the threshold for TCER in China,decreasing from the southeastern coast to the northwest inland.TCER occurred infrequently in northern China but had a high intensity and was highly localized.The frequency and intensity of TCER showed slightly increasing trends over time and was most likely to occur in August(41.0%).Most of the TC precipitation processes with extreme rainfall lasted for four to six days,with TCER mainly occurring on the third to fourth days.TCER with wide areas showed a northwestward prevailing track and a westward prevailing track.Strong TCs are not always accompanied by extreme precipitation while some weak TCs can lead to very extreme rainfall.A total of 64.7%(35.3%)of the TCER samples occurred when the TC was centered over the land(sea).TCER≥250 mm was located within 3°of the center of the TC.When the center of the TC was located over the sea(land),the extreme rainfall over land was most likely to appear on its northwestern(northeastern)side with a dispersed(concentrated)distribution.TCER has unique climatic characteristics relative to the TC precipitation.  相似文献   

对金厂峪金矿床深部矿化规律的初步认识   总被引：2，自引：2，他引：0  

张宝林  蔡新平 《地质与勘探》1998,34(5):14-17

根据金厂峪金矿深部（０－１０００ｍ标高之间）获得的最新钻孔岩芯资料,结合上地质观察,室内工作,探讨了该矿床化规律以及矿体的产状特征,对探矿工程的布设提出了建议。解释了深部矿化富集与分散的原因,进一步确认了对该区中生代褶皱构造控矿的认识。指出今后深部找矿中应注意发生新的矿化类型。研究中生代褶皱构造与太古代韧性发带的关系,蚀变与矿化的关系。  相似文献   

依不同纬度变量的子午线弧长正反解公式的级数展开     

过家春  李厚朴  庄云玲  李大军  吴艳兰 《测绘学报》2016,45(5):560-565

推导了以归化纬度、地心纬度解算子午线弧长的展开公式,同时又根据拉格朗日反演定理,得到了由子午线弧长反解归化纬度、地心纬度的直接公式。该组公式与子午线弧长正反解公式的大地纬度表达在结构形式上保持一致,进一步揭示了子午线弧长同3种纬度变量之间的内在联系。分析表明,基于归化纬度的子午线弧长解算与大地主题解算方法具有理论上的统一性,正反解精度均高于传统基于大地纬度的展开。  相似文献   

Paleomagnetic constraints on the tectonic history of the major blocks of China duing the Phanerozoic     

Zhu Rixiang  Yang Zhenyu  Wu Hanning  Ma Xinghua  Huang Baochun  Meng Zifang  Fang Dajun 《中国科学D辑(英文版)》1998,41(2):1-19

Paleomagnetic study of China and its constraints on Asia tectonics has been a hot spot. Some new paleomagnetic data from three major blocks of China. North China Block (NCB), Yangtze Block (YZB) and Tarim Block (TRM) are first reported, and then available published Phanerozoic paleomagnetic poles from these blocks with the goal of placing constraints on the drift history and paleocontinental reconstruction are critically reviewed. It was found that all three major blocks were located at the mid-low latitude in the Southern Hemisphere during the Early Paleozoic. The NCB was probably independent in terms of dynamics. its drift history was dominant by latitudinal placement accompanying rotation in the Early Paleozoic. The YZB was close to Gondwanaland in Cambrian, and separated from Gondwanaland during the Late-Middle Ordovician. The TRM was part of Gondwanaland, and might be close to the YZB and Australia in the Early Paleozoic. Paleomagnetic data show that the TRM was separated from Gondwanaland during the Late-Middle Ordovician, and then drifted northward. The TRM was sutured to Siberia and Kazakstan blocks during the Permian, however, the composite Mongolia-NCB block did not collide with Siberia till Late Jurassic. During Late Permian to Late Triassic, the NCB and YZB were characterized by northern latitudinal placement and rotation on the pivot in the Dabie area. The NCB and YZB collided first in the eastern part where they were located at northern latitude of about 6°—8°, and a triangular oceanic basin remained in the Late Permian. The suturing zone was located at northern latitude of 25° where the two blocks collided at the western part in the Late Triassic. The collision between the two blocks propagated westward after the YZB rotated about 70° relative to the NCB during the Late Permian to Middle Jurassic. Then two blocks were northward drifting (about 5°) together with relative rotating and crust shortening. It was such scissors-like collision procedure that produced intensive compression in the eastern part of suturing zone between the NCB and YZB, in which continental crust subducted into the upper mantle in the Late Permian, and then the ultrahigh-pressure rocks extruded in the Late Triassic. Paleomagnetic data also indicate that three major blocks have been together clockwise rotating about 20° relative to present-day rotation axis since the Late Jurassic. It was proposed that Lahsa Block and India subcontinent successively northward subducted and collided with Eurasia or collision between Pacific/Philippines plates and Eurasia might be responsible for this clockwise rotating of Chinese continent.  相似文献   

安徽宣城茶亭铜金矿区外围找矿潜力分析     

洪大军  宋世明  张旭  陈科夫  刘宏 《中国地质调查》2022,9(3):23-31

安徽宣城茶亭铜金矿是皖东南首次发现的大型斑岩型铜金矿。近年来在该地区实施的一系列物探工作以及验证物探异常获得新的找矿成果,区内铜多金属矿与岩浆活动十分密切,中酸性侵入岩能引起地磁异常,碳酸盐岩能引起重力异常,黄铁矿、黄铜矿能引起可控制音频大地电磁(controlled source audio magnetotelluric method,CSAMT)低阻异常,研究发现茶亭斑岩型铜金矿物探异常特征为: 低磁、高重力场、CSAMT低阻。根据上述综合找矿信息,在茶亭斑岩型铜金矿外围深部找矿中发现了新的含金隐爆角砾岩体以及铅锌矿体,指明了茶亭外围找矿方向,为进一步的找矿突破提供了思路。  相似文献   

航空影像直角房屋轮廓半自动提取     

李大军  杜神斌  郭丙轩  薛万唱  游畸 《测绘通报》2018,(4):112-115,120

以精确提取房屋轮廓为目的,提出了一种航空影像中直角房屋轮廓半自动提取算法。该方法首先通过人工使用鼠标依次在房屋边缘线的大致位置画直线,再利用影像分割分别得到所对应的窗口影像;进而利用LSD算法对窗口影像提取直线;然后以其为初值,在保证其整体位移和数值偏差最小的情况下利用最小二乘算法在原始影像图上进行线拟合和直角化;最后连接角点,完成房屋轮廓信息的提取。试验结果表明,该方法不仅有效地减轻了工作人员的劳动强度,而且定位精度高于人工切准。  相似文献   

基于时间序列分析法的岩溶泉水位预测     

郭艺  秦大军  王枫  甘甫平  闫柏琨 《中国岩溶》2021,40(4):689-697

济南城区岩溶泉是当地主要的供水水源,查明泉水动态规律并科学合理的预测泉水位对于泉域岩溶水资源的开发利用和保护具有重要意义。本文首先应用时间序列分析法将趵突泉和黑虎泉自2012年5月2日至2018年10月31日的逐日水位数据分解为趋势项、周期项和随机项,分析其水位动态变化规律并建立水位预测模型,结果显示泉水位动态在该阶段无显著趋势性;但受降水的影响,泉水位动态变化呈现两个主要的周期,多年性变化（3.2年）和季节性变化;同时由于受到各种无规律干扰因素的影响,泉水位动态呈现随机波动的随机项。其次,利用2018年11月1日至2020年8月24日的逐日泉水位数据验证上述水位预测模型的预测精度,结果表明该模型运行合理,预测效果较好,具有一定的实用价值。最后利用该模型预测了2020年8月25日至2022年10月31日泉水位动态变化,为当地岩溶水资源开发和管理提供了依据。   相似文献   

武汉城市圈农业旅游目的地空间分布及影响因素   总被引：2，自引：0，他引：2  

李细归  吴清  刘大均 《热带地理》2014,34(3):422-428

农业旅游目的地的开发与建设是推动城乡一体化的重要途径之一。运用标准差椭圆分析法、最邻近指数、核密度估计法等分析武汉城市圈农业旅游目的地的空间分布特征及其影响因素。结果表明：1）武汉城市圈农业旅游目的地空间分布具有明显的向心性,圈层分布格局较为明显;2）其总体上属于集聚型分布,但不同区域的农业旅游目的地分布类型差异显著;3）其在空间分布形态上呈“片状与点状”并存的格局,不同区域的农业旅游目的地分布格局差异较大;4）武汉城市圈农业旅游目的地空间分布受城市等级、交通、河流以及区域经济和旅游发展水平等因素影响较为明显,不同规模等级的城市对农业旅游目的地空间分布影响的差异性较大,高速公路对农业旅游目的地空间分布的作用突出。最后,结合分布特征和影响因素,有针对性地对武汉城市圈的建设和发展提出了建议。  相似文献   

Integrated urban and rural water affairs management reform in China: Affecting factors   总被引：1，自引：0，他引：1  

Dajun Shen  Bin Liu 《Physics and Chemistry of the Earth》2008,33(5):364-375

The institutional evolution is often induced by some factors. This paper intends to analyze the affecting factors in integrated urban and rural water affairs management reform in China. The integrated urban and rural water affairs management reform is to restructure the governmental organizational setting in water management by forms of water affair bureau or re-designing functions of current water resources bureau to incorporate part or all functions of resources management, service regulation and environment management in water sector. The analyses selected some natural and socio-economic factors. The results point out that the integrated urban and rural water affairs management reform is a factor-induced institutional evolution. The factors promoting this reform include occasional drought events, higher central water investment percentage; but the data from the urban sector do not provide the support to the reform.  相似文献   

Seafloor geodetic network establishment and key technologies     

Yang  Yuanxi  Liu  Yanxiong  Sun  Dajun  Xu  Tianhe  Xue  Shuqiang  Han  Yunfeng  Zeng  Anmin 《中国科学:地球科学(英文版)》2020,63(8):1188-1198

Seafloor geodetic network construction involves the development of geodetic station shelter, network configuration design, location selection and layout, surveying strategy, observation model establishment and optimization, data processing strategy and so on. This paper tries to present main technological problems involved in the seafloor geodetic network construction, and seek the technically feasible solutions. Basic conceptions of developing seafloor geodetic station shelters for shallow sea and deep-sea are described respectively. The overall criteria of seafloor geodetic network construction for submarine navigation and those of network design for crustal motion monitoring are both proposed. In order to enhance application performances of the seafloor geodetic network, the seafloor network configuration should prefer a symmetrical network structure. The sea surface tracking line measurements for determining the seafloor geodetic station position should also adopt an approximately symmetrical configuration, and we recommend circle tracking line observations combined with cross-shaped line(or double cross-shape line) observations for the seafloor positioning mode. As to the offset correction between the Global Navigation Satellite System antenna phase center and the acoustic transducer, it is recommended to combine the calibration through external measurements and model parameter estimation. Besides, it is suggested to correct the sound speed error with a combination of observation value correction and parameterized model correction, and to mainly use the model correction to reduce the influence of acoustic ray error on the seafloor positioning. Following the proposed basic designs, experiments are performed in shallow sea area and deep-sea area respectively. Based on the developed seafloor geodetic shelter and sufficient verification in the shallow sea experiment, a long-term seafloor geodetic station in the deep-sea area of 3000 m depth was established for the first time, and the preliminary positioning result shows that the internal precision of this station is better than 5 cm.  相似文献