基于广义回归神经网络的全球表层海水1°×1°二氧化碳分压数据推演     

钟国荣  李学刚  曲宝晓  王彦俊  袁华茂  宋金明 《海洋学报》2020,42(10):70-79

表层海水二氧化碳分压是评估海洋碳源汇强度的关键参数，但其实测数据较少、时空分布极不均匀，导致二氧化碳交换通量的估算有很大的不确定性，海洋源汇特征就不能确切获取。为了解决这个难题，在收集的表层大洋二氧化碳地图(Surface Ocean CO₂ Atlas，SOCAT)实测数据集基础上，运用广义回归神经网络建立二氧化碳分压与经纬度、时间、温度、盐度和叶绿素浓度间的非线性关系，构建了1998?2018年间全球1°×1°经纬度的表层海水二氧化碳分压格点数据，其标准误差为16.93 μatm，平均相对误差为2.97%，优于现有研究中的前反馈神经网络、自组织映射神经网络和机器学习算法等方法。根据构建的数据所绘制的全球表层海水二氧化碳分压的分布与现有研究有较好的一致性。  相似文献   

基于大数据分析下的气候模型     

张宸豪  冯曦  冯卫兵  刘涛  丁坤 《海洋科学》2020,44(10):1-11

为研究全球变暖与极寒天气间的关系，对加拿大13个省代表性测站10年的观测数据进行时空变化趋势分析，采用经验正交函数（EOF）寻找海洋表面温度历史数据的变化规律。另外利用BP神经网络建立了年平均温度、日降水量与地球吸热、散热、海表面温度、当地纬度间的关系，预测未来25年气候的变化，并建立了“极寒天气”与气候变化的关系模型。研究表明：高纬度地区温度、降水量普遍较低，同经度地区的温度差异较小且降水量变化不大；加拿大地区温度呈周期性变化，符合北半球的季节变化特征；北大西洋的东部与其他海洋的温度是反相关的，西太平洋南北回归线附近的海洋表面温度升高；“极寒天气”出现频率与气候变化有一定关系，局地极寒现象与全球变暖的大趋势并不矛盾。本研究为人们认识和理解“全球变暖”提供了一个新的思路。  相似文献   

Detection and mapping of bracken fern weeds using multispectral remotely sensed data: a review of progress and challenges     

Trylee Nyasha Matongera  Onisimo Mutanga  Timothy Dube  Romano Trent Lottering 《国际地球制图》2018,33(3):209-224

Bracken fern is one of the major invasive plants distributed all over the world currently threatening socio-economic and ecological systems due to its ability to swiftly colonize landscapes. The study aimed at reviewing the progress and challenges in detecting and mapping of bracken fern weeds using different remote sensing techniques. Evidence from literature have revealed that traditional methods such as field surveys and modelling have been insufficient in detecting and mapping the spatial distribution of bracken fern at a regional scale. The applications of medium spatial resolution sensors have been constrained by their limited spatial, spectral and radiometric capabilities in detecting and mapping bracken fern. On the other hand, the availability of most of these data-sets free of charge, large swath width and their high temporal resolution have significantly improved remote sensing of bracken fern. The use of commercial satellite data with high resolution have also proven useful in providing fine spectral and spatial resolution capabilities that are primarily essential to offer precise and reliable data on the spatial distribution of invasive species. However, the application of these data-sets is largely restricted to smaller areas, due to high costs and huge data volumes. Studies on bracken fern classification have extensively adopted traditional classification methods such as supervised maximum likelihood classifier. In studies where traditional methods performed poorly, the combination of soft classifiers such as super resolution analysis and traditional methods of classification have shown an improvement in bracken fern classification. Finally, since high spatial resolution sensors are expensive to acquire and have small swath width, the current study recommends that future research can also consider investigating the utility of the freely available recently launched sensors with a global footprint that has the potential to provide invaluable information for repeated measurement of invasive species over time and space.  相似文献   

利用“L-R”剖分及三角形聚合的近似等面积菱形格网建模     

苑争一  赵学胜  赵静 《测绘通报》2018,(1):107-111

球面菱形格网因其几何结构简单、方向一致、径向对称等特性,在空间操作和数据集成方面有着广泛的应用。本文基于“纬线环法”构建了球面四元三角剖分模型,分析了该方法带来的格网单元面积变形及其位置分布,发现该模型的三角单元面积变形具有“锯齿状”分布特征,即相邻的上下两个格网单元总是一大一小交替分布,而且变形方向一致。据此通过合并上下两个相邻三角形格网单元,构建了一种近似等面积的菱形剖分模型。结果表明,相比较于其他球面菱形格网生成方法,该方法计算简单、格网单元方向一致（长轴沿南北向分布）;同时,格网单元的面积变形更小、分布更加均匀。  相似文献   

Future Changes in Extreme High Temperature over China at 1.5℃-5℃ Global Warming Based on CMIP6 Simulations   总被引：1，自引：0，他引：1  

Guwei ZHANG  Gang ZENG  Xiaoye YANG  Zhihong JIANG 《大气科学进展》2021,38(2):253-267

Extreme high temperature(EHT)events are among the most impact-related consequences related to climate change,especially for China,a nation with a large population that is vulnerable to the climate warming.Based on the latest Coupled Model Intercomparison Project Phase 6(CMIP6),this study assesses future EHT changes across China at five specific global warming thresholds(1.5℃-5℃).The results indicate that global mean temperature will increase by 1.5℃/2℃ before 2030/2050 relative to pre-industrial levels(1861-1900)under three future scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5),and warming will occur faster under SSP5-8.5 compared to SSP1-2.6 and SSP2-4.5.Under SSP5-8.5,global warming will eventually exceed 5℃ by 2100,while under SSP1-2.6,it will stabilize around 2℃ after 2050.In China,most of the areas where warming exceeds global average levels will be located in Tibet and northern China(Northwest China,North China and Northeast China),covering 50%-70%of the country.Furthermore,about 0.19-0.44 billion people(accounting for 16%-41%of the national population)will experience warming above the global average.Compared to present-day(1995-2014),the warmest day(TXx)will increase most notably in northern China,while the number of warm days(TX90p)and warm spell duration indicator(WSDI)will increase most profoundly in southern China.For example,relative to the present-day,TXx will increase by 1℃-5℃ in northern China,and TX90p(WSDI)will increase by 25-150(10-80)days in southern China at 1.5℃-5℃ global warming.Compared to 2℃-5℃,limiting global warming to 1.5℃ will help avoid about 36%-87%of the EHT increases in China.  相似文献   

From China’s Heavy Precipitation in 2020 to a “Glocal” Hydrometeorological Solution for Flood Risk Prediction     

Huan WU  Xiaomeng LI  Guy J.-P.SCHUMANN  Lorenzo ALFIERI  Yun CHEN  Hui XU  Zhifang WU  Hong LU  Yamin HU  Qiang ZHU  Zhijun HUANG  Weitian CHEN  Ying HU 《大气科学进展》2021,38(1):1-7

The prolonged mei-yu/baiu system with anomalous precipitation in the year 2020 has swollen many rivers and lakes,caused flash flooding,urban flooding and landslides,and consistently wreaked havoc across large swathes of China,particularly in the Yangtze River basin.Significant precipitation and flooding anomalies have already been seen in magnitude and extension so far this year,which have been exerting much higher pressure on emergency responses in flood control and mitigation than in other years,even though a rainy season with multiple ongoing serious flood events in different provinces is not that uncommon in China.Instead of delving into the causes of the uniqueness of this year’s extreme precipitation-flooding situation,which certainly warrants in-depth exploration,in this article we provide a short view toward a more general hydrometeorological solution to this annual nationwide problem.A“glocal”(global to local)hydrometeorological solution for floods(GHS-F)is considered to be critical for better preparedness,mitigation,and management of different types of significant precipitation-caused flooding,which happen extensively almost every year in many countries such as China,India and the United States.Such a GHS-F model is necessary from both scientific and operational perspectives,with the strength in providing spatially consistent flood definitions and spatially distributed flood risk classification considering the heterogeneity in vulnerability and resilience across the entire domain.Priorities in the development of such a GHS-F are suggested,emphasizing the user’s requirements and needs according to practical experiences with various flood response agencies.  相似文献   

湘西-黔东下寒武统清虚洞组藻灰岩沉积特征及其找矿意义          下载免费PDF全文

付胜云  张丰  曾健康  龙国华  邓蕾  程怡宁  李大江 《中国地质调查》2018,5(3):56-65

铅锌矿是湘西-黔东地区的优势矿种,资源丰富,开发历史悠久,找矿潜力巨大。综合分析前人有关湘西-黔东生物礁的资料,介绍了藻灰岩的沉积特征,并结合大量实际地质资料,对藻灰岩控矿进行了论述。结果表明: 成矿物质主要来源于藻类及碳酸盐泥对Pb²⁺、Zn²⁺离子的吸取,矿床成因属于沉积成岩矿床类型,兼有成岩期后矿床性质; 藻礁灰岩与不同岩性的接合部位及其附近等微地球化学障区,往往就是铅锌富矿体产出部位; 藻礁灰岩与礁间通道的薄层泥质白云质灰岩呈指状交叉接触处,也常有铅锌富矿体产出; 铅锌富矿体基本上产于清虚洞组灰岩段中,且明显受该段藻礁灰岩控制。为满足国内外对铅锌矿日益增长的消费需要,深入研究区内铅锌矿的地层岩相岩石控矿因素及其富集规律,指导该地区藻灰岩中铅锌矿找矿工作,具有重要的现实意义。  相似文献   

西秦岭温泉—中川一带金属矿床的成矿规律及找矿预测   总被引：1，自引：1，他引：0       下载免费PDF全文

刘彦良  高雅  罗维斌  季文中 《中国地质调查》2018,5(4):40-49

西秦岭温泉—中川一带实施的1:5万矿产地质调查项目,共圈定1:5万局部高磁异常33处,1:5万地球化学综合异常11处,发现矿点2处,矿化点5处,矿种有金、钼、铁、铜、铷等。通过分析研究区成矿地质条件、1:5万地球物理和地球化学综合异常特征、矿(化)点特征及分布规律等,阐明了该区成矿时空分布规律和矿产共生组合规律,划分成矿远景区9处,提交找矿靶区6处。对其中2处找矿靶区进行槽探验证的结果为: 关子镇幅玉杨观找矿靶区圈定了4条含铷矿化伟晶岩脉和多处铁矿化破碎蚀变带,具有形成伟晶岩型铷矿的潜力; 礼县幅李坝金矿床南侧百叶沟—河西沟找矿靶区圈定了14条蚀变破碎带,在矿化蚀变带内圈定了11条金矿(化)体,具有形成构造蚀变岩(微细粒浸染状)型金矿床的潜力。  相似文献   

剪切带型金矿中金沉淀的力化学过程与成矿机理探讨   总被引：2，自引：1，他引：1  

程南南  刘庆  侯泉林  卫巍  石梦岩  何苗  郭谦谦 《岩石学报》2018,34(7):2165-2180

剪切带型金矿是一种重要的金矿床类型,有关该类型金矿的成因问题已开展了大量研究,但对于剪切带中金的沉淀析出机制和成矿过程仍存在较大争议,对于赋矿部位的构造属性与矿床关系的研究尚显薄弱。对此笔者整理分析了近年来国内外有关剪切带型金矿的研究进展,并结合我国胶东金矿的研究实例,运用断层阀和力化学理论分析发现,无论是脆性还是韧性剪切带,无论是脉型还是蚀变岩型金矿,其成矿的关键部位均与构造应力集中而导致的脆性破裂(特别是R、T、R’破裂的产生)和碎裂作用以及(多期)岩体侵位密切相关,并且脆性破裂所导致的压力骤降从而引发流体闪蒸的力化学过程可能是造成金沉淀析出成矿的有效机制,其中多期岩体侵位所提供的流体是成矿的物质基础。此外,从国内外实例可以看出,剪切带中的脆性破裂不仅发生于脆性或脆韧性构造域,也可以发生在较深层次的韧性构造域中,尽管韧性域中产生脆性破裂的原因还不十分清楚,但这可能是韧性剪切带成矿的关键机制之一。最后,综合岩体、流体、剪切带三者对成矿的耦合作用,文中提出剪切带型金矿的成矿机理为:(多期)岩体侵位-热液活动-构造剪切-应力集中-脆性破裂(碎裂)产生-压力骤降-流体闪蒸-元素(金)析出,如此循环往复方可形成大型剪切带型金矿。  相似文献   

陕西凤太矿集区多金属成矿作用的构造控制   总被引：3，自引：0，他引：3  

王义天  陈绍聪  胡乔青  张娟  刘协鲁  黄诗康 《岩石学报》2018,34(7):1959-1976

陕西凤县-太白(简称凤太)矿集区铅、锌、金、银、铜多金属资源丰富,已发现二十余个大中小型矿床。在大地构造位置上,凤太矿集区位于南秦岭造山带北缘,紧邻商丹缝合带。以往的工作缺乏对矿集区整体的构造研究,本次工作通过比较系统的构造测量和解析,提出在南秦岭晚三叠世碰撞造山过程中,凤太矿集区南北两条边界断裂带的左行走滑运动导致在区内衍生了NNE向主压应力场,从而形成了NWW向复式褶皱、脆韧性剪切带、断裂和节理(纵向破裂)、B型线理,以及NNE向断裂和节理(横向破裂)、劈理、张裂隙等一系列构造组合,所有构造形迹都是在统一构造应力场下随着构造层次不断抬升,脆韧性和脆性递进变形叠加的产物,共同构成了一个大型压扭性走滑双重构造变形系统。在构造几何学上,凤太矿集区整体上表现为一个隔档式复式褶皱,由一组NWW向紧闭复背斜和一组相对宽缓复向斜组成。区内的多金属成矿作用、岩浆活动、动力变质变形作用的同位素年龄数据集中于230~190Ma。综合地质演化和成矿作用的研究成果,提出在南秦岭碰撞造山过程中引发的动力变质变形作用和岩浆活动提供了成矿元素和成矿流体,在温压梯度以及浮力效应的驱动下向上运移至走滑双重构造变形系统中的有利扩容空间中发生充填型和交代型矿化,即凤太矿集区多金属矿床是区域大规模变形变质-岩浆活动-流体作用的产物,是在构造作用这一主导因素控制下形成的一个多金属后生热液成矿系统。  相似文献