AAC算法的大气校正复合改进算法     

尹梅  田淑芳  李士杰 《遥感学报》2016,20(3):450-458

利用模拟数据,评价Autonomous Atmospheric Compensation(AAC)算法的抗噪性,认为AAC算法的抗噪性较弱。基于TASI实测数据,利用AAC算法开展反演计算时,计算结果呈现出多样性问题。结合In-scene Atmospheric Compensation(ISAC)算法中黑体像元的标定方法,提出了一种复合改进算法。首先,利用ISAC算法反演的大气透过率和路径辐射,重新计算AAC算法中大气透过率之比(Tr)和相邻两强弱吸收通道的路径辐射之差(Pd),再次,运用经验公式获得稳定的大气反演结果(大气透过率和路径辐射),有效解决了计算结果多样性的问题。利用复合改进算法,开展的温度与发射率分离实验,证明反演得到的发射率波谱更接近野外实测波谱。  相似文献   

华蓥山中段地区地下水资源量评价   总被引：1，自引：1，他引：0  

康小兵  罗声  许模  刘宏 《中国岩溶》2018,37(4):527-534

四川华蓥山中段地区水流失比较严重,供需矛盾突出,水环境持续恶化,不但影响到居民正常的生产和生活,而且严重影响了该地区国民经济的建设和发展。通过野外调查和综合分析现场收集的资料,总结出华蓥山中段地区地下水资源量流失情况:该区每年流失的水资源量约为0.914 4亿m3,且华蓥山褶皱西翼水流失总量大于东翼,而西翼北端是区内水流失量最严重的区域,其水资源量流失的影响因素主要为气候、社会发展及人类活动等。   相似文献   

Spatiotemporal change patterns of urban lakes in China’s major cities between 1990 and 2015     

Cong Xie  Leiguang Wang  Xing Fang  Wenzhi Liao 《International Journal of Digital Earth》2018,11(11):1085-1102

China has experienced unprecedented urbanization in the past decades, resulting in dramatic changes in the physical, limnological, and hydrological characteristics of lakes in urban landscapes. However, the spatiotemporal dynamics in distribution and abundance of urban lakes in China remain poorly understood. Here, we characterized the spatiotemporal change patterns of urban lakes in China’s major cities between 1990 and 2015 using remote-sensing data and landscape metrics. The results showed that the urban lake landscape patterns have experienced drastic changes over the past 25 years. The total surface area of the urban lakes has decreased by 17,620.02?ha, a decrease of 24.22%, with a significant increase in the landscape fragmentation and a reduction in shape complexity. We defined three lake-shrinkage types and found that vanishment was the most common lake-shrinkage pattern, followed by edge-shrinkage and tunneling in terms of lake area. Moreover, we also found that urban sprawl was the dominant driver of the lake shrinkage, accounting for 67.89% of the total area loss, and the transition from lakes to cropland was also an important factor (19.86%). This study has potential for providing critical baseline information for government decision-making in lake resources management and urban landscape design.  相似文献   

旅游活动与水环境耦合分析——以玉龙雪山-丽江盆地为例     

窦文康  王泽平  方金鑫  韩彤彤  蒲焘  张鹏 《冰川冻土》2021,43(4):1210-1217

玉龙雪山是我国季风海洋型冰川发育最为典型的代表性地区,也是北半球最靠近赤道的现代冰川区。丽江市的部分水源来自于玉龙雪山冰川融水,同时玉龙雪山景区每年吸引着上千万的游客来欣赏现代冰川。旅游活动与水环境息息相关且相互作用,水环境的准确刻画是指导与优化区域旅游活动的基础。以世界著名旅游城市丽江市为例,基于实地采样与数据分析,对2018年丽江市的旅游活动与水环境进行耦合分析。结果表明：丽江市旅游活动与水体污染耦合度极高,旅游活动与水体富营养化和水体毒理的耦合度较低。旅游活动与水环境存在较强的关联,特别是与水环境指标中的高锰酸盐指数,存在强烈的耦合关系。总体上,旅游活动与水环境存在相关关系,旅游旺季水环境质量较旅游淡季更差。  相似文献   

中国地下水资源演变趋势及影响因素分析   总被引：1，自引：0，他引：1       下载免费PDF全文

陈飞  徐翔宇  羊艳  丁跃元  郦建强  李原园 《水科学进展》2021,31(6):811-819

中国地下水资源发生了显著变化,全面摸清地下水资源演变趋势及其影响因素是治理和管理地下水资源的基础。基于全国水资源调查评价、中国水资源公报等资料,对中国60余年来地下水资源的演变规律与影响因素进行了系统分析。结果表明：全国地下水资源量总体稳定,但区域演变趋势差异明显,海河区、辽河区、黄河区呈明显衰减态势;地下水补给结构发生重大变化,由自然补给演变为自然与人工补给并存的模式;地下水排泄结构发生巨大变异,由天然排泄逐渐演变为以人工排泄为主。海河区、松花江区、黄河区、西北诸河区等区域地下水补给排泄关系严重失衡,超采问题突出;降水变化、下垫面条件改变、人类活动干扰是地下水资源变化的主要原因。  相似文献   

Microplastic pollution in surface water and sediments of Qinghai-Tibet Plateau: Current status and causes     

《China Geology》2021,4(1):178-184

To study the current status and causes of the microplastic pollution in surface water of the Qinghai-Tibet Plateau, this paper compared the average microplastic abundance in sediments and surface water of the Qinghai-Tibet Plateau and the results are as follows. First, the average microplastic abundance in surface water of the independent rivers and the whole area is 247–2686 items/m³ and 856 items/m³, respectively. The average microplastic abundance in sediments of independent rivers or lakes and the whole area is 0–933 items/m² and 362 items/m², respectively. Meanwhile, the degree of microplastic pollution in river sediments is higher than that in lake sediments, and the rivers suffering from microplastic pollution mainly include the Brahmaputra River, Tongtian River, and Nujiang River. Second, compared with the microplastic pollution in other areas of the world, the levelof microplastic pollution in the lakes and rivers of the Qinghai-Tibet plateau is not lower than that of well-developed areas with more intensive human activities. Finally, this study suggests that relevant government departments of the Qinghai-Tibet Plateau should strengthen waste management strategies while developing tourism and that much attention should be paid to the impacts of microplastics in the water environment.©2021 China Geology Editorial Office.  相似文献   

地质岩芯科技资源科普化工作探索与实践——以自然资源实物地质资料中心为例     

张志伟  刘文卿  袁野  高建伟  苏桂芬 《地质论评》2024,70(1):362-366

岩芯科技资源科普化是打通地质科研—科普链条的重要途径,本文通过梳理我国岩芯科技资源现状,分析了岩芯科技资源科普化的现实意义,重点阐述了岩芯科技资源在向地质科普转化5个方面的探索与实践,提出了今后岩芯科技资源科普化工作应建立良好政策机制制度、转变科研人员观念、科技知识向科普转化水平、新技术新手段的应用以及做好科普活动的实施总结等5项工作建议。  相似文献   

A comparison of frameworks for separating the impacts of human activities and climate change on river flow in existing records and different near-future scenarios     

Soghra Andaryani  Vahid Nourani  James Ball  Saeed Jahanbakhsh Asl  Hamidreza Keshtkar  Dennis Trolle 《水文研究》2021,35(7):e14301

  相似文献   

长蛸的盐度耐受性及盐度胁迫对其血细胞和体内酶活力的影响   总被引：1，自引：0，他引：1  

张玉玉  王春琳  李来国 《台湾海峡》2010,29(4):452-459

通过控制暂养水体盐度,用盐度突变与盐度渐变2种方法测定长蛸的盐度耐受性.测定了长蛸血细胞密度、各类血细胞数量比例以及各种酶的活力几组数据,并分析其血细胞与体内酶活力的变化.结果表明：长蛸的生存盐度范围为7.0~30.3,适宜盐度范围为16.3~27.3,最适盐度范围为18.3~24.3,对盐度的适应范围较广,有利于长蛸大规模养殖的开展.在盐度胁迫下,长蛸血细胞密度,各种血细胞数量比例均发生显著改变,长蛸个体也随着胁迫加大变得越来越不适应,出现喷墨、休克、甚至死亡,这表明长蛸的免疫机能降低.无论在低盐度还是高盐度胁迫情况下,受渗透压的影响,长蛸肌体大量吸水和失水,呼吸作用减弱,体内供氧降低,导致长蛸体内有氧呼吸降低和无氧呼吸提高,于是催化有氧呼吸的LDH酶活力降低.同时,细胞内与免疫和消化相关的细胞器由于细胞吸水或失水作用功能受到影响,保护酶（SOD、POD、CAT）、磷酸酶（ACP、AKP）和消化酶（蛋白酶和脂肪酶）的活力均呈下降趋势.由此可见,盐度胁迫对长蛸的影响是显著的.  相似文献   

Seismic activity related to the 1991 eruption of Colima Volcano,Mexico     

Francisco Núñez-Cornú  F. Alejandro Nava  Servando De la Cruz-Reyna  Zenón Jiménez  Carmen Valencia  Rosalía García-Arthur 《Bulletin of Volcanology》1994,56(3):228-237

Ten years after the last effusive eruption and at least 15 years of seismic quiescence, volcanic seismic activity started at Colima volcano on 14 February 1991, with a seismic crisis which reached counts of more than 100 per day and showed a diversity of earthquake types. Four other distinct seismic crises followed, before a mild effusive eruption in April 1991. The second crisis preceded the extrusion of an andesitic scoriaceous lava lobe, first reported on 1 March; during this crisis an interesting temporary concentration of seismic foci below the crater was observed shortly before the extrusion was detected. The third crisis was constituted by shallow seismicity, featuring possible mild degassing explosion-induced activity in the form of hiccups (episodes of simple wavelets that repeat with diminishing amplitude), and accompanied by increased fumarolic activity. The growth of the new lava dome was accompanied by changing seismicity. On 16 April during the fifth crisis which consisted of some relatively large, shallow, volcanic earthquakes and numerous avalanches of older dome material, part of the newly extruded dome, which had grown towards the edge of the old dome, collapsed, producing the largest avalanches and ash flows. Afterwards, block lava began to flow slowly along the SW flank of the volcano, generating frequent small incandescent avalanches. The seismicity associated with the stages of this eruptive activity shows some interesting features: most earthquake foci were located north of the summit, some of them relatively deep (7–11 km below the summit level), underneath the saddle between the Colima and the older Nevado volcanoes. An apparently seismic quiet region appears between 4 and 7 km below the summit level. In June, harmonic tremors were detected for the first time, but no changes in the eruptive activity could be correlated with them. After June, the seismicity decreasing trend was established, and the effusive activity stopped on September 1991.  相似文献