Interdecadal change in Western Pacific Subtropical High and climatic effects

Western North Pacific Subtropical High is a very important atmospheric circulation system influencing the summer climate over eastern China. Its interdecadal change is analyzed in this study. There is a significant decadal shift in about 1979/1980. Since 1980, the Western North Pacific Subtropical High has enlarged, intensified, and shifted southwestward. This change gives rise to an anti-cyclonic circulation anomaly over the region from the South China Sea to western Pacific and thus causes wet anomalies over the Yangtze River valley. During the summers of 1980–1999, the precipitation is 63.9 mm above normal, while during 1958–1979 it is 27.3 mm below normal. The difference is significant at the 99% confidence level as at-test shown. The southwestward expanding of the Western North Pacific Subtropical High also leads to a significant warming in southern China, during 1980–1999 the summer mean temperature is 0.37°C warmer than that of the period 1958–1979. The strong warming is primarily due to the clearer skies associated with the stronger downward air motion as the Western North Pacific Subtropical High expanding to the west and controlling southern China. It is also found that the relative percentage of tropical cyclones in the regions south of 20°N is decreasing since the 1980s, but in the regions north of 20°N that is increasing at the same time. The Western North Pacific Subtropical High responds significantly to sea surface temperature of the tropical eastern Pacific with a lag of one-two seasons and simultaneously to sea surface temperature of the tropical Indian Ocean. The changes in the sea surface temperatures are mainly responsible for the interdecadal variability of the Western North Pacific Subtropical High.     

Permafrost science and secondary education: direct involvement of teachers and students in field research

Permafrost and periglacial geomorphology are absent from the science curriculum in most secondary schools in the United States. This is an unfortunate situation given the recent increases in development and environmental concerns in northern latitudes and high-mountain areas, and the interesting examples of basic scientific principles found in the history of research on periglacial geomorphology and permafrost. In 1997 and 1998, a University of Delaware research group studying permafrost and periglacial geomorphology in northern Alaska participated in the National Science Foundation's (NSF) Teachers Experiencing the Antarctic and Arctic (TEA) Program. In each of these years, a high school teacher and a student traveled as part of the research team to the North Slope of Alaska. They learned about the landscape, collected active-layer thickness and temperature measurements, and assisted in data analysis. Results from studies of active-layer thickness variability and ground temperature contributed to a series of long-term observations and international research on the impacts of global climate change. Since their expeditions, the teachers have shared their experiences with their classrooms and communities in several ways, including public lectures and the Internet. Classroom activities are available to the public through the TEA web site (http://tea.rice.edu). This experience may heighten public awareness of permafrost and contribute to it becoming a useful part of the secondary curriculum.     

青海盐湖镁资源开发与利用研究进展

本文简要介绍了青海盐湖资源的分布、储量,重点对青海盐湖镁资源的研究开发和利用现状进行了综述,分析了其中存在的问题和关键技术瓶颈。在此基础上,对未来青海盐湖镁资源的高值化利用和研究方向进行了展望,并提出了相应的建议。     

高碳铬铁EDXRF分析中的制样条件优化

利用能量色散X射线荧光光谱分析技术(EDXRF)检测高碳铬铁,能实现对主次组分的同时测量,且无需对铬铁样品进行化学处理。实验以荧光强度和测试精密度为指标,采用单因素试验考察了粉末压片制样过程中称样量、粘结剂种类与用量、研磨时间、压片压力、保压时间等制样条件对测量结果的影响趋势,并将优化后的条件用于对高碳铬铁的检测。结果表明,使用6 g样品和0.4 g微晶纤维素,研磨时间为3 min,压片压力为40 MPa,保压时间为1 min时制得的样片表面光滑,测定重现性好。精密度和稳定性分析表示,各元素测定结果的相对标准偏差(RSD)均小于0.5%,证明优化制样条件后可以满足利用EDXRF定量分析铬铁主次元素的要求。     

基于GF-1与Sentinel-2融合数据的地膜识别方法研究

随着我国地膜使用面积的增加和人们对土壤微塑料污染问题的日益关注,大尺度的地膜遥感识别已成为农业生产管理、土壤污染防治的必要手段。针对地膜光谱反射特征的复杂性以及基于单一遥感影像光谱特征识别方法错分率高等问题,该文以河北省邯郸市邱县为试验区,利用GF-1数据的空间细节与Sentinel-2数据的光谱信息进行NN Diffuse Pan Sharpening融合,据此建立地膜识别的特征矩阵(NDVI、MNDWI、NDBI、IBI、PSI),基于该特征矩阵可实现自动阈值地膜分层分类识别。多种方法的地膜识别结果精度对比表明:多源光学遥感数据融合方法的总体精度为94.87%,Kappa系数达0.89,显著优于基于单一数据源的深度学习法的精度(93.14%)以及基于传统机器学习分类方法的支持向量机(85.91%)和随机森林分类法(86.78%)的精度;通过与Sentinel-2多光谱影像融合,弥补了GF-1数据光谱分辨率低的缺陷,实现了多源数据在地膜识别中的优势互补,可为相关部门农业规划与管理以及生态环境保护等研究提供大尺度、高精度的地膜分布参考数据。     

自动赋初值的LSB-Snake模型的道路半自动提取方法研究

LSB-Snake模型是一个半自动提取线状地物的有效方法,但是在提取道路时需要人工输入道路特征（与背景相比道路的亮暗、宽度）作为初始值,在初始种子点稀少的时候不够稳健,且降低了LSB-Snake模型的效率。因此,本文提出了自动赋初值的LSB-Snake模型,采用自适应模板匹配方法为LSB-Snake模型提供初始特征,同时在初始种子点的基础上自动生成可靠、密集的点,共同作为LSB-Snake模型的种子点参与道路提取。对IKONOS和QuickBird进行道路提取的试验证明：在给定同样数目的初始种子点的情况下,提出的自动赋初值LSB-Snake模型比LSB-Snake模型更加稳健;由于无需人工输入道路特征,自动化程度更高;在道路附近地物阴影、遮挡较多的情况下,抗干扰能力更强。     

高分辨率卫星遥感影像在土地利用调查和动态监测中的应用

结合乐清市土地调查的具体实践,对高分辨率卫星遥感影像在土地利用调查和动态监测中的应用进行探讨。以高分辨率卫星影像作为信息源,应用3S技术,进行土地利用调查和动态监测。可改变传统工作方式,把大量艰苦的野外作业变成室内作业,不仅省时、省力、成本低,且客观性和科学性强。所获得的数据易于转换为GIS数据格式,而且能及时、全面、准确地获得土地变化信息,具有常规方法所不能比拟的优点。     

QUICKBIRD影像用于城市用地信息提取方法

本研究采用基于对象的分类技术,依据高分辨率卫星影像QUICKBIRD的特征,对乌鲁木齐市用地信息的提取进行了研究。结果表明,此种分类方法具有较高的分类精度和较快的分类速度。     

浅谈遥感应用领域对卫星影像的要求

卫星遥感影像在国民经济建设诸多行业中的应用日益广泛,这种广泛性使得行业对卫星遥感数据提出了不同的要求。本文主要从空间分辨率、时间分辨率、光谱分辨率和影像质量等方面对其进行阐述。     

高渗压下水岩相互作用试验研究

新研发的岩石高压渗透试验仪以静态伺服阀为主要控制元件,在脱离计算机控制条件下可使试样进水端水压保持不变。出水端水压采用调速阀控制,实现了高渗透压力下长时间的水-岩相互作用试验研究。在此基础上,提出了水-岩作用渗透液体不同时段各离子浓度变化的分析方法,并容易得到不同时段试样渗透性变化规律。为研究水-岩作用对岩石强度的影响,按基本相同条件,对该试样及未经长期水-岩渗流作用同一岩性试样进行了高渗压下的常规三轴试验,提出以试样临近破坏时的有效侧向应力大小进行强度分析,并按上述实际所加侧向压力大小及有效侧向压力大小,进行了常规饱水三轴压缩试验。试验得出,所研究蚀变岩在高渗压下水-岩作用结果与常温、常压条件测试结果类似,蚀变岩与库水的水化学反应微弱,对其自身岩体的渗透性及力学性质影响均较小。