海表面温度时空变异特征及对验证误差影响     

蒋锦刚  徐曜  聂晨晖  潘骁骏  周斌 《遥感学报》2019,23(2):336-348

海洋要素的变化存在明显的区域性和季节性的变化特性,本文选择海洋要素中最为突出的海表面温度(SST)要素作为主要分析参数,设计时空变异参数的计算指标,分析时空变异对验证误差影响的关系,通过研究及试验的数据精度验证,证明了时空变异是造成误差的直接原因之一。强烈的时空属性变异,在验证过程中会引入很大的验证误差,处于不同变异等级区划的数据,其验证结果相对误差可达13.08%,变异越剧烈的区域,精度验证效果越差,验证误差就越大,这些误差并非完全是遥感产品的误差,验证结果不具有代表性,不能真实的反映遥感产品的误差特征。对于SST等海洋遥感产品验证时,需要考虑时空变异对验证误差的影响和贡献,合理选择验证试验区域、代表性的评价数据集和科学的评价方法。  相似文献   

中国上市公司的时空变化及机制研究     

李黎  李成名  戴昭鑫  吴政  满旺 《测绘科学》2019,44(6):324-329,336

针对在中国地区发展不均衡的态势下,上市公司分布格局时空演变问题,该文对2009-2017年中国大陆各省上市公司的数量和总资产采用Local Moran’s I指数与Getis-Ord Gi*统计量进行研究,分析了中国大陆上市公司的空间分布格局和时间演变趋势,总结出中国上市公司相关指标的高值聚集和高低聚集分布格局、热点区域及其经济辐射能力。并且以北京、上海和广东为热点区域典型代表,从上市公司产业结构和区域经济发展两方面对时空变化机制的成因进行深入探讨。  相似文献   

Statistical analysis of surface urban heat island intensity variations: A case study of Babol city,Iran     

Qihao Weng  Mohammad Karimi Firozjaei  Amir Sedighi  Seyed Kazem Alavipanah 《地理信息系统科学与遥感》2019,56(4):576-604

The urban heat island is considered as one of the most important climate change phenomena in urban areas, which can result in remarkable negative effects on flora, concentration of pollutants, air quality, energy and water consumption, human health, ecological and economic impacts, and even on global warming. The variation analysis of the surface urban heat island intensity (SUHII) is important for understanding the effect of urbanization and urban planning. The objective of this study was to present a new strategy based on the Shannon’s entropy and Pearson chi-square statistic to investigate the spatial and temporal variations of the SUHII. In this study, Landsat TM, ETM+, OLI and TIRS images, MODIS products, meteorological data, topographic and population maps of the Babol city, Iran, from 1985 to 2017, and air temperature data recorded by ground recorder devices in 2017 were used. First, Single-Channel algorithm was used to estimate land surface temperature (LST), and the maximum likelihood classifier was employed to classify Landsat images. Then, based on LST maps, surface urban heat island ratio index was employed to calculate the SUHII. Further, several statistical methods, such as the degree-of-freedom, degree-of-sprawl and degree-of-goodness, were used to analyse the SUHII variation along different geographic directions and in various time periods. Finally, correlation between various parameters such as air temperature, SUHII, population variation and degree-of-goodness index values were investigated. The results indicated that the SUHII value increased by 24% in Babol over different time periods. The correlation coefficient yielded 0.82 between the values of the difference between the mean air temperature of the urban and suburbs and the SUHII values for the geographic directions. Furthermore, the correlation coefficient between the population variation and the degree-of-goodness index values reached 0.8. The results suggested that the SUHII variation of Babol city had a high degree-of-freedom, high degree-of-sprawl and negative degree-of-goodness.  相似文献   

1901—2018年三江源地区大气冻融指数变化特征     

陈方方  罗栋梁  刘磊  金会军  李超 《冰川冻土》2021,43(2):417-426

三江源地区是我国重要生态安全屏障,冻土是其高寒生态系统的重要组成部分,冻土的变化深刻影响高寒生态系统固碳及水源涵养.基于英国东英吉利大学(University of East Anglia,UEA)气候研究中心(Climatic Research Unit,CRU)月平均气温再分析资料,利用线性倾向法和滑动平均法并结合...  相似文献   

大洋调查中海山地磁测量的静日变化校正方法   总被引：2，自引：1，他引：1  

刘保华  刘晨光  裴彦良  阚光明 《海洋学报》2008,30(6):94-98

针对大洋调查中海山地磁测量时难以设立静日变化观测站的问题,提出了一种基于多项式拟合最小二乘算法的日变校正方法,即假设静日变化磁场可以用一个关于时间的高阶多项式来拟合,利用主测线和联络测线交点误差的最小二乘估计求得多项式的系数,从而得到静日变化曲线。从调查测得的磁场中减掉静日变化磁场即可得消除静日变化影响后的海山地磁异常。理论模型和实际资料处理都表明,这种方法不仅可以较好地消除静日变化的影响,而且用计算机实现也简单。为了提高静日变化校正结果,讨论了为提高静日变化校正效果,在大洋调查中测量海山地磁时应注意的几个问题。  相似文献   

Long-term stability of the fish assemblages in a warm-temperate South African estuary     

Nicola C. James  Alan K. Whitfield  Paul D. Cowley 《Estuarine, Coastal and Shelf Science》2008,76(4):723-738

Little is known about long-term changes in estuarine fish populations and related environmental variations. Fishes in the temporarily open/closed East Kleinemonde Estuary were sampled bi-annually, in summer and winter, using seine and gill nets between December 1994 and July 2005. A total of 18 families, represented by 33 species, were recorded. The 10 most abundant species caught were consistently recorded in catches each year, but CPUE of individual species varied on an annual basis and this can often be related to mouth state. Multivariate analyses of the annual marine fish community identified two distinct groups, with more species recorded during years that succeeded spring (September to November) mouth-opening events than in years following no mouth-opening events in spring. Interannual community stability (IMD) and seriation (IMS) also increased from the years following no opening events in spring to the years that succeeded spring opening events. These results highlight the importance of the timing of mouth opening to the marine fish community in a temporarily open/closed estuary. This study reinforces the importance of long-term studies to understanding community changes in estuaries caused by environmental variations over different time scales.  相似文献   

Inter-annual variability in phytoplankton summer blooms in the freshwater tidal reaches of the Schelde estuary (Belgium)   总被引：1，自引：1，他引：0  

Marie Lionard  Koenraad Muylaert  Abdel Hanoutti  Tom Maris  Michle Tackx  Wim Vyverman 《Estuarine, Coastal and Shelf Science》2008,79(4):694-700

The inter-annual variability in phytoplankton summer blooms in the upper reaches of the Schelde estuary was investigated between 1996 and 2005 by monthly sampling at 10 stations. The large inter-annual variations of the chlorophyll a concentration in the freshwater tidal reaches were independent from variations in chlorophyll a in the tributary river Schelde. Summer mean chlorophyll a concentrations were significantly negatively correlated with flushing rate (Spearman correlation: r = −0.67, p = 0.05, n = 9) but not with temperature, irradiance and suspended particulate matter or dissolved silica (DSi) concentrations. During dry summers, low flushing rates permitted the development of dense phytoplankton populations in the upper part of the estuary, while during wet summers high flushing rates prevented the development of dense phytoplankton blooms. Flushing rate was also found to be important for the phytoplankton community composition. At low flushing rates, the community was dominated by diatoms that developed within the upper estuary. At high flushing rates, chlorophytes imported from the tributary river Schelde became more important in the phytoplankton community. The position of the chlorophyll a maximum shifted from the head of the estuary when flushing rates were low, to more downstream when flushing rates were high. Although DSi concentrations tended to be lower during years of high phytoplankton (mainly diatom) biomass, the relation with flushing rate was not significant.  相似文献   

Seasonal and spatial variation in abundance and egg production of Paracalanus parvus (Copepoda: Calanoida) in/out Jiaozhou Bay, China     

X.H. Sun  S. Sun  C.L. Li  G.T. Zhang 《Estuarine, Coastal and Shelf Science》2008,79(4):637-643

The spatial distribution of stage-specific abundance and reproduction of the copepod Paracalanus parvus were studied from October 2005 to September 2006 in the Jiaozhou Bay. This copepod occurred continuously in this bay throughout the year. The species reached the lowest abundance in April and peaked in June. From October to December, distribution center mainly occurred in offshore water and at the mouth of the bay. In winter, early copepodites and adults gradually decreased and till February, most of the population was only comprised of CIV–CV stages. Overwintering copepodites matured in March and males tended to mature before female. From May to September, each stage occurred in the population and gradually reached high abundance. Temperature and chlorophyll a (Chl-a) concentration in the three stations can't clearly explain the seasonal variation in stage-specific abundance, so we surmised the important effect of the Yellow Sea. Egg production rate (EPR) reached its lowest in winter and peaked in June at 60.8 eggs female⁻¹ day⁻¹ in nearshore water. In the warming period, EPR in nearshore water was statistically higher and EPR > 10 eggs female⁻¹ day⁻¹ lasted longer than that in offshore water, showing the importance of nearshore water for recruitment of P. parvus. Our study showed that EPR was positively related to temperature and total chlorophyll a in offshore water and mouth of the bay. In nearshore water, the relationships between EPR and temperature and Chl-a in three size fractions were not the same as those in offshore water, suggesting complicated ecosystem in such a eutrophic area in warming period.  相似文献   

广利港河道水位变化及河口拦门沙地形变化分析研究     

林维田  吴永亭  刘建立 《海岸工程》2008,27(3):9-14

根据1984年和2007年两次对广利港航道水深测量的结果,分析研究了广利港航道内的水位变化规律,以及河口拦门沙的地形特征。结果表明广利港航道内水位变化复杂,拦门沙形态改变,水深变浅,原有的航道已经消失。  相似文献   

钱塘江强潮河段江道缩窄治理研究   总被引：1，自引：0，他引：1  

陈来华  潘存鸿 《海洋工程》2008,26(2):96-102

对钱塘江强潮河段江道缩窄治理进行研究。首先,回顾治理方案的比选,江道全线缩窄时河轴线线路和河道宽度的确定原则,以及不同河段的指数放宽率。然后,介绍了在涌潮汹涌、滩涂淤坍变化剧烈的强潮河段,实施筑堤所采取的工程措施的步序与要点。最后,分析论证了大规模江道缩窄治理后河床、潮汐、洪水位及涌潮高度等特征值的变化。可供进一步深入理论研究和工程施工参考运用。  相似文献