Analysis of correlations between time series with the use of the phase spectrum     

M. I. Fortus 《Izvestiya Atmospheric and Oceanic Physics》2007,43(5):555-568

In connection with the problem of revealing cause-effect relations among different climatic characteristics, methods for determining the dependence between time series on the basis of selected auto-and cross-covariance functions and periodograms expressed in terms of the Fourier coefficients of the initial series are discussed. Real time series do not always satisfy the conditions of statistical stationarity, so that their analysis requires a combination of statistical and deterministic approaches. The possibility of using the above numerical characteristics in relation to such series is considered. Characteristic features of describing finite segments of time series with the use of their Fourier coefficients is studied in detail. The main emphasis is on the determination of the time shifts (delays) at which the covariance between the series is maximal. The problems that appear during a practical implementation of the periodogram method for shift estimation are discussed. A previously unknown formula that is necessary for further studies and relates the Fourier transform of a selected correlation function to the periodogram of the series is derived.  相似文献   

Relationships between benthic macrofauna and habitat suitability for juvenile common sole (Solea solea, L.) in the Vilaine estuary (Bay of Biscay, France) nursery ground     

D. Nicolas  F. Le Loc'h  Y. Dsaunay  D. Hamon  A. Blanchet  O. Le Pape 《Estuarine, Coastal and Shelf Science》2007,73(3-4):639-650

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Water vapor in the atmosphere over the northern Tien Shan     

V. N. Aref’ev  F. V. Kashin  V. K. Semenov  R. M. Akimenko  N. E. Kamenogradskii  N. I. Sizov  V. P. Sinyakov  L. B. Upenek  V. P. Ustinov 《Izvestiya Atmospheric and Oceanic Physics》2006,42(6):739-751

Refined data of systematic measurements of total water vapor in the atmosphere from May 1980 to April 2005 are presented. The data were obtained at the Issyk Kul atmospheric-monitoring station by the method of solar molecular-absorption spectroscopy. Over 25 years, the annual mean water-vapor content in the atmosphere increased by 4.5% at a mean rate of increase of 0.18% per year. However, the water-vapor content decreased in the last five years. The results of statistical processing of experimental data (general statistical characteristics, correlation coefficients, composite oscillations) are described. A refined model is proposed for forecasts of temporal variations in the monthly mean and annual mean water-vapor contents for the coming years. The model includes a linear trend and the sum of oscillations with periods close to the periods of a number of well-known geophysical phenomena. Regression equations are proposed to relate the water-vapor content in the atmospheric column to the surface temperature and absolute humidity.  相似文献   

Sources and biogeochemical cycling of particulate selenium in the San Francisco Bay estuary     

Martina A. Doblin  Stephen B. Baines  Lynda S. Cutter  Gregory A. Cutter 《Estuarine, Coastal and Shelf Science》2006,67(4):681-694

As part of a study of estuarine selenium cycling, we measured the concentration, chemical form (speciation), and distribution of particulate selenium under various river flow conditions in the North San Francisco Bay (from the Golden Gate to the Sacramento and San Joaquin Rivers). We also conducted laboratory studies on the accumulation of selenium by phytoplankton, the critical first step in the transformation of dissolved to particulate selenium. Total particulate selenium concentration in the North SF Bay was relatively constant between high and low flow periods, ranging spatially from 0.05 to 0.35 nmol l⁻¹ and comprising between 5 and 12% of the total water column selenium inventory. Mean concentrations were generally highest in the Carquinez Strait–Suisun Bay region (salinity 0–17) and lowest in Central Bay. However, selenium content of suspended particles varied with river flow, with higher content during low flow (9.76 ± 4.17 nmol g⁻¹; mean ± sd; n = 67) compared to high flow (7.10 ± 4.24 nmol g⁻¹; n = 39). Speciation analyses showed that most particulate selenium is organic selenide (45 ± 27%), with a smaller proportion (typically <30%) of adsorbed selenite + selenate and a varying proportion (35 ± 28%) of elemental selenium. Based on the amount of elemental selenium in the seston (total suspended material), we calculate that resuspension of estuarine sediments could contribute 29–100% of particulate selenium in the water column. While selenium content of SF Bay seston (>0.4 μm) is relatively unenriched compared to phytoplankton (13.6–155 nmol g⁻¹ dry weight) on a mass basis, when normalized to carbon or nitrogen, seston contains a similar selenium concentration to SF Bay sediments or phytoplankton cultures. SF Bay seston is thus comprised of selenium-rich phytoplankton and phyto-detritus, but also inorganic clay mineral particles that effectively “dilute” total particulate selenium. Selenium concentrations in algal cultures (11 species) exposed to 90 nmol l⁻¹ selenite show relatively large differences in selenium accumulation, with the diatoms, chlorophytes and cryptophytes generally having lower selenium cell content (3.8 ± 2.7 × 10⁻⁹ nmol selenium cell⁻¹) compared to the dinoflagellates (193 ± 73 × 10⁻⁹ nmol selenium cell⁻¹). Because phytoplankton are such a rich (but variable) source of selenium, their dynamics could have a profound effect on the particulate selenium inventory in the North SF Bay.  相似文献   

碳水化合物的组合合成     

王群  于广利 《中国海洋大学学报(自然科学版)》2001,31(1):45

碳水化合物的组合合成是一项新兴技术，该技术可以在短时间内合成大量用于进行生物活性筛选的寡糖及拟糖物。液相与固相合成技术可以极大地加快药物研究与开发进程。作者针对该技术在碳水化合物合成方面的研究进展情况进行讨论。  相似文献   

Late-Quaternary supply of terrigenous organic matter to the Congo deep-sea fan (ODP site 1075): implications for equatorial African paleoclimate   总被引：3，自引：1，他引：3  

J. Holtvoeth  T. Wagner  B. Horsfield  C. Schubert  U. Wand 《Geo-Marine Letters》2001,21(1):23-33

Late-Quaternary sections (about 1 Ma) from the Congo deep-sea fan (ODP Leg 175, site 1075) were used to reconstruct the terrigenous organic matter supply to the easternmost equatorial Atlantic Ocean. Variations in quantity and quality of the riverine organic matter reflect the interaction between the paleoclimatic development within the continental catchment area and the paleoceanographic conditions in the Congo river plume. To characterize the delivery of organic matter from terrigenous and marine sources, we used elemental and bulk carbon isotopic analyses, Rock-Eval pyrolysis, lignin chemistry, and organic petrology. High-amplitude fluctuations occurring about every 15-25 ka reveal a mainly precessional control on organic sedimentation. Results from Rock-Eval pyrolysis indicate a mixed kerogen type III/II, as would be anticipated in front of a major river. Fluctuations in T_max from Rock-Eval pyrolysis demonstrate pronounced cyclic changes in the delivery of low- and high-mature organic matter. Contribution of the low-mature organic fraction was strongest during warm climates supporting enhanced marine production offshore of the Congo. Organic petrological observations confirm the existence of abundant terrigenous plant tissues, both non-oxidized (vitrinite) and oxidized (inertinite). Charcoal-like organic matter (fusinite) is attributed to periods of increased bush fires in the continental hinterland, and implies more arid climatic conditions. Results from ratios of specific phenolic lignin components suggest that terrigenous organic matter in Late-Quaternary sections of site 1075 mainly derives from non-woody angiosperm tissue, i.e., grasses and leaves. Correlation between the amount of specific lignin phenols and the bulk '¹³C_org signature fosters the conclusion that an appreciable amount of the terrigenous organic fraction derives from C4 plant matter. This may cause an underestimation of the terrigenous proportion of bulk organic matter when assessments are based on bulk carbon isotopic signatures alone.  相似文献   

黄海区水母类的生态研究     

王真良 《海洋科学进展》1996,(1)

本文根据１９８２年４月２１日～５月１２日，７月２３日～８月５日，１０月１２～３０日在３４°３０′Ｎ以北．１２４°Ｅ以西黄海水域污染现状综合调查中获得的样品和资料，分析了本海区水母类的种类组成，数量分布以及季节变化。调查海区共鉴定有３４种水母，其中优势种有盘形美螅水母Ｃｌｙｔｉａｄｉｓｃｏｉｄａ，四枝管水母Ｐｒｏｂｏｓｃｉｄａｃｔｙｌａｆｌａｖｉｃｉｒｒａｔａ，五角水母Ｍｕｇｇｉａｅａａｔｔａｎｔｉｃａ。秋季（１０月）为水母类总个体数的高峰期（８．６７个／ｍ３）。水母类的分布与水温、盐度密切相关，海流或水团也起重要作用．水母类分布的变更可以反映出沿岸水和外海水相互推移和消长状况。  相似文献   

植物硅酸体的研究及在我国第四纪地质学中的初步应用   总被引：8，自引：0，他引：8  

王永吉  衡平 《海洋地质与第四纪地质》1991,11(3):113-124

本文简述了国外植物硅酸体(植物蛋白石)这门新兴学科的进展情况,介绍了植物硅酸体研究在我国第四纪地质学中如古气候与古环境、地层时代、考古等方面的初步应用。  相似文献   

南沙群岛海区冬夏季中、深层海流的计算     

黄企洲  王文质  傅孙成 《热带海洋学报》1994,(2)

根据１９８８年夏季和１９８９年冬季南沙群岛海区两个航次的温、盐度调查资料，运用β螺旋方法对调查海区的海流进行了计算。计算结果表明，该海区表、中层环流相对比较一致，深层流动状态与表、中层的差异较大，其中的局地环流的季节变化不明显。此外，在北康暗沙与南薇滩之间，夏季中、深层和冬季深层都明显反映出存在着一个迄今未见报道的局地反气旋式环流。文章对上述结果与该海区已有的一些海流分析结果作了比较。  相似文献   

Sediment dynamics of the Huanghe (Yellow River) delta and neighboring gulf of Bohai,People's Republic of China: Project overview   总被引：6，自引：0，他引：6  

G. H. Keller  D. B. Prior 《Geo-Marine Letters》1986,6(2):63-66

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