高分六号宽幅相机在轨几何定标及精度验证   总被引：1，自引：0，他引：1  

王密  郭贝贝  龙小祥  薛麟  程宇峰  金淑英  周晓 《测绘学报》2020,49(2):171-180

高分六号宽幅相机能够实现单相机成像幅宽优于800 km,对大尺度地表观测和环境监测具有独特优势。在轨几何定标是光学遥感卫星几何处理的关键环节,直接影响影像的几何质量。本文充分考虑高分六号宽幅相机超大视场的畸变特性以及多谱段的成像特点,提出宽幅相机在轨几何定标方法,采用基于探元指向角的几何定标模型补偿宽幅相机系统误差,通过绝对定标和相对定标方法联合估计各波段的内外定标参数。利用Landsat 8影像、资源三号DSM为参考数据,对宽幅相机进行绝对定标处理,再利用ASTER GDEM为参考数据进行相对定标处理,其几何定标结果表明,高分六号宽幅影像绝对定位精度在3像素左右,内部几何精度能稳定在1像素,且波段间配准精度在0.3像素以内,表明在轨几何定标后高分六号宽幅影像几何质量得到了明显的提升。  相似文献   

海南省连片贫困地区农户致贫风险分析   总被引：4，自引：1，他引：3  

张金萍  宋伟  林丹  余珍鑫  李庭筠  罗邱戈  程叶青 《地理科学》2020,40(4):608-616

农村贫困与减贫是世界性难题,也是中国各级政府高度重视并着力解决的重大民生问题。基于农户及致贫风险的文献梳理,从区位、社会和劳动力3个要素维度构建了农户致贫风险分析的二元Logistic回归模型。采用484户农户问卷调查数据,分析了海南省连片贫困地区农户的致贫风险,提出有效减贫和持续发展对策。研究发现:① 海南连片贫困地区生态环境良好但贫困发生率较高,家庭劳动力较充裕但受教育水平较低,子女教育支出负担重,因病因残致贫比例较高,女性务工人口较多,农户自身脱贫致富的发展动力不足。② 海拔高度200 m以下、男性户主、拥有残疾或患病成员、务工人口比例低、女性务工人员占比高、以及单位劳动力供养学生数高的农户具有更大的致贫风险。③ 研究未发现女性户主、少数民族、低受教育水平户主、大型规模家庭有更高的致贫风险,女性成员比例、抚养比等因素对农户贫困影响较小。激发农户内生动力、大力发展特色化和规模化农业、增加农户就业机会、加强针对农民工、女性务工人员和病残群体的社会保障等减贫政策制定实施是实现脱贫攻坚目标的重要途径。  相似文献   

干旱区地表温度和热岛效应演变研究——以宁夏沿黄城市带为例          下载免费PDF全文

孙灏  马立茹  蔡创创  黄涛  吕林涛  阮琳  陈伟 《干旱区地理》2020,43(3):694-705

宁夏沿黄城市带位于宁夏东北部，不仅是干旱地区地理研究的重点区域，也是宁夏经济发展的核心区域。基于2000—2018年的MODIS地表温度、土地覆盖类型以及植被覆盖率数据，通过计算热岛比例指数 (URI)，利用Mann-Kendall非参数检验及Sen’s斜率估计法，对宁夏沿黄城市带近20 a白天和夜间的地表温度（LST）和热岛效应时间变化进行分析。结果表明：（1） 近20 a来，宁夏沿黄城市带大部分地区[WTBX]LST变化不显著，但在植被覆盖率增加区域，白天LST显著减小而夜间LST显著上升；植被覆盖率减小区域与之相反；夜间LST[WTBZ]变化幅度强于白天。（2） 宁夏沿黄城市带的热岛效应通常在白天较弱、在夜间较强；白天和夜间时刻的城市热岛效应在一年内呈现不同的季节变化特点,白天春冬较强，夜间夏季较强；过去近20 a，宁夏沿黄城市带白天热岛效应呈现稍微减弱趋势，夜间热岛效应呈现稍微增强趋势，但变化趋势均不显著。（3） 从植被覆盖率和地物类型两个影响因素的研究表明，植被覆盖率是影响地表温度变化的重要因素，城建区与郊区主要地物温差的改变是城市热岛强度变化的重要原因。从长时间序列变化的角度详细分析干旱区城市热岛的特征和变化原因，可为干旱区城市热岛带来的环境问题治理提供参考，也为研究干旱区热岛提供了借鉴。  相似文献   

Correspondence between the large volcanic eruptions and ENSO events over AD 1525–2000     

Fang  Xiuqi  Zheng  Xue  Zhang  Xing 《地理学报(英文版)》2020,30(1):103-118

ENSO is an interannual mode which may be affected by external forcing, such as volcanic eruptions. Based on the reconstructed volcanic eruptions chronology and ENSO sequences, both 195 large volcanic eruptions(VEI≥4) and 398 ENSO(El Ni?o and La Ni?a) events were extracted from 1525 to 2000. An analysis of the correspondence between the large volcanic eruptions and ENSO events was performed by matching the large volcanic eruptions with the types and magnitudes of ENSO events present in the 0–2 years after the eruptions. The results show the following:(1) The percentages of ENSO events within the 3 years after the large eruptions had increased to 68.3% from 31.7% compared with those with no-eruptions in the previous 0–2 years. In addition, the ratio of El Ni?o to La Ni?a events turned from 2:3 to 1:1, and more El Ni?o events occurred in the 0 year after eruptions in the low-latitudes of the Northern Hemisphere and in the tropics but more La Ni?a events occurred in the 0 year after in the high-latitudes of the Northern Hemisphere and the Southern Hemisphere.(2) After the eruptions, the weak(W) El Ni?o events had increased by 8 percentage points and the very strong(VS) El Ni?o events had decreased by 10 percentage points; conversely, there was a decrease by 15 percentage points of the weak La Ni?a events and an increase by 11.4 percentage points of the very strong La Ni?a events. Specifically, the percentages of strong La Ni?a events increased to a peak at 1(+1) year after the eruptions.(3) The percentage of eruptions followed by single-year ENSO was the greatest. The percentage of ENSO events that occurred in the consecutive 2 years following an eruption was approximately equal to the percentage of events that occurred consecutively 3 years following an eruption, and both sets of ENSO magnitudes showed a decreasing trend.  相似文献   

空间分析与生物地球化学循环:西藏林周县大骨节病患病村与非患病村的比较研究     

田原  查欣洁  高星  戴尔阜  余成群 《资源与生态学报(英文版)》2020,11(2):232-246

西藏林周县是我国大骨节病(KBD)患病较为严重的地区之一,本文将林周县作为研究区,通过使用地理探测器(GeoDetector)量化分析KBD患病率风险因子的影响,并使用环境化学方法验证空间分析结果。通过对10个潜在影响因子的分析以及对当地KBD患病村和非患病村的土壤-水-粮食-人这一生物地球化学循环的环境化学分析,结果表明:(1)林周县KBD由一组多重且交互作用的环境影响因子共同作用影响,其中最重要的控制因子是地层因子;(2)所有环境介质(土壤、水、谷物)及人体组织中的硒元素浓度在KBD患病区均低于非患病区;(3)当地居民对硒和铬的摄入严重不足,尤其是KBD患病村中居民硒元素平均日摄入量(ADD)大约仅为世界卫生组织(WHO)建议的成人基本摄入量下限的4%;(4)我们推测,当地居民患病主要是由于地层这一影响因子,这是由于通过生态系统的迁移转化导致当地人口严重硒缺乏,最终导致地方性生物地球化学硒缺乏。  相似文献   

Development and evaluation of a storm surge warning system in Taiwan     

Mei-Ying Lin  Wen-Yih Sun  Ming-Da Chiou  Chih-Ying Chen  Hao-Yuan Cheng  Cheng-Hsin Chen 《Ocean Dynamics》2018,68(8):1025-1049

An operational storm surge forecasting system aimed at providing warning information for storm surges has been developed and evaluated using four typhoon events. The warning system triggered by typhoon forecasts from Taiwan Cooperative Precipitation Ensemble Forecast Experiment (TAPEX) has been executed with two storm surge forecasting scenarios with and without tides. Three numerical experiments applying different meteorological inputs have been designed to assess the impact of typhoon forcing on storm surges. One uses synthetic wind fields, and the others use realistic wind fields with and without adjustments to the initial wind fields for the background circulation. Local observations from Central Weather Bureau (CWB) weather stations and tide gauge stations are used to evaluate the wind fields and storm surges from our numerical experiments. The comparison results show that the accuracy of the storm surge forecast is dominated by the track, the intensity, and the driving flow of a typhoon. When the structure of a typhoon is disturbed by Taiwan’s topography, using meteorological inputs from real wind fields can result in a better typhoon simulation than using inputs from synthetic wind fields. The driving flow also determines the impact of topography on typhoon movement. For quickly moving typhoons, storm forcing from TAPEX is reliable when a typhoon is strong enough to be relatively unaffected by environmental flows; otherwise, storm forcing from a sophisticated typhoon initialization scheme that better simulates the typhoon and environmental flows results in a more accurate prediction of storm surges. Therefore, when a typhoon moves slowly and interacts more with the topography and environmental flows, incorporating realistic wind fields with adjustments to the initial wind fields for the background circulation in the warning system will obtain better predictions for a typhoon and its resultant storm surges.  相似文献   

Brittleness characteristics of tight oil siltstones     

Wen-Hui Tan  Jing Ba  Meng-Qiu Guo  Hui Li  Lin Zhang  Ting Yu  Hao Chen 《应用地球物理》2018,15(2):175-187

Rock brittleness directly affects reservoir fracturing and its evaluation is essential for establishing fracturing conditions prior to reservoir reforming. Dynamic and static brittleness data were collected from siltstones of the Qingshankou Formation in Songliao Basin. The brittle–plastic transition was investigated based on the stress–strain relation. The results suggest that the brittleness indices calculated by static elastic parameters are negatively correlated with the stress drop coefficient and the brittleness index B₂, defined as the average of the normalized Young’s modulus and Poisson’s ratio, is strongly correlated with the stress drop. The brittleness index B₂, Young’s modulus, and Poisson’s ratio correlate with the brittle minerals content; that is, quartz, carbonates, and pyrite. We also investigated the correlation between pore fluid and porosity and dynamic brittle characteristic based on index B₂. Pore fluid increases the plasticity of rock and reduces brittleness; moreover, with increasing porosity, rock brittleness decreases. The gas-saturated siltstone brittleness index is higher than that in oil- or water-saturated siltstone; the difference in the brittleness indices of oil- and water-saturated siltstone is very small. By comparing the rock mechanics and ultrasonic experiments, we find that the brittleness index obtained from the rock mechanics experiments is smaller than that obtained from the ultrasonic experiments; nevertheless, both decrease with increasing porosity as well as their differences. Ultrasonic waves propagate through the rock specimens without affecting them, whereas rock mechanics experiments are destructive and induce microcracking and porosity increases; consequently, the brittleness of low-porosity rocks is affected by the formation of internal microcrack systems.  相似文献   

Environmental changes in the north‐east Sunda region over the last 40 000 years     

Chuanxiu Luo  Simon Haberle  Zhuo Zheng  Rong Xiang  Chixin Chen  Gang Lin  Kumar Sazal 《第四纪科学杂志》2019,34(3):245-257

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Morphological and molecular diagnoses of Polydora brevipalpa Zachs,1933(Annelida: Spionidae) from the shellfish along the coast of China     

YE Lingtong  YAO Tuo  WU Lin  LU Jie  WANG Jiangyong 《中国海洋湖沼学报》2019,(2)

Shell-boring species Polydora brevipalpa Zachs, 1933 is redescribed based on morphological observations and molecular approach for future unambiguous identification. Genetic distance analyses showed that the interspecific polydorid variation(16.7%–25.6%) was at least 15 times higher than the intraspecific one(0.2%–0.9%) based on the cytochrome c oxidase subunit I(CO1) gene sequences of polydorids. However, 18 S rDNA variation pattern demonstrated a rather narrow barcoding gap, with the interspecific polydorid variation(0.5%–5.6%) being very close to the intraspecific one(0.0%–0.4%). As such, the CO1 gene exhibited better DNA barcode for identification of polydorids than the 18 S rDNA gene because of the su ciently large barcoding gaps. Analysis of molecular variance results based on CO1 gene sequences showed that most variations in sequences(97.79%) lay within groups of adult worms and egg capsules rather than between them. This indicated that egg capsules from Crassostrea gigas(Thunberg,1793) in Ningbo and Nantong were related to the adult worms from Patinopecten yessoensis(Jay, 1857) in Dalian, and both of them belonged to P. brevipalpa. This result was further supported by parsimony network analysis, which showed that egg capsules collected from dif ferent localities and adult worms shared a single haplotype. This study was the first to report both P. brevipalpa infestation on C. gigas and to utilise the known CO1 sequences of the adult polydorids to validate morphologically unidentified egg capsules or early larvae. P. brevipalpa was most possibly brought to Chinese waters through transportation of Pa. yessoensis brood stock from Japan.  相似文献   

基于Android平台的分布式无线微震采集站布站与监控软件研究与实现     

刘诗扬  张启升  张启卯  乔帅卿  晏使楚  李文豪  郭丰  汪永青  衡星  柯振  张璇 《地球物理学进展》2020,(1):331-338

由于地震勘探仪器呈现小型化、无线化、智能化发展趋势,传统操作平台无法满足便携式勘探仪器使用需要.因此本文利用Android移动设备便携性、普及性高,用户基础好的特点,实现了基于Android平台的无线微震采集站布站与监控软件.该软件在大范围野外施工中,为施工人员提供包括定位、测距、测角、网络监测等全程可视化布站功能,同时提供监测施工中小型、大型微震采集站阵列实时网络情况,以及采集站状态的智能控制、数据实时监控等功能.经过施工测试,软件稳定性好、便携性高,极大提高野外施工效率.  相似文献