Techniques for statistical analysis and prediction of geophysical fluid systems     

Russ E. Davis 《地球物理与天体物理流体动力学》2013,107(1):245-277

Abstract

Application of statistical estimators to analysis and prediction is examined from the point of view of geophysical fluid dynamics. The fundamental difficulty is that estimators constructed from observational records of limited length (the usual case in GFD) are sensitive to sampling errors in the statistics upon which they are based. To achieve meaningful results, the number of data, or input, parameters must be limited. The relationship between statistical and dynamical models (particularly clear for linear systems) coupled with certain statistical methods are explored with respect to the problem of input parameter selection, both for linear and nonlinear systems. Methods of assessing the effects of sampling errors in hindcasts are discussed and techniques for minimizing these effects in forecasts are evaluated. A method of efficiently condensing statistical models to a few input parameters and transfer functions is given. Finally the steps of hindcast analysis and forecaster construction are discussed from the practical point of view.  相似文献   

Feasibility of using full tensor gradient (FTG) data for detection of local lateral density contrasts during reservoir monitoring   总被引：1，自引：0，他引：1  

Alexander Droujinine  Alexander Vasilevsky  Russ Evans 《Geophysical Journal International》2007,169(3):795-820

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The USDA-Agricultural Research Service's long term agro-ecosystems Walnut Gulch Experimental Watershed,Arizona, USA     

David C. Goodrich  Philip Heilman  Mark Nearing  Mary Nichols  Russ L. Scott  C. Jason Williams  Joel Biederman 《水文研究》2021,35(9):e14349

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Sorption of metals on humic acid   总被引：1，自引：0，他引：1  

H. Kerndorff  M. Schnitzer 《Geochimica et cosmochimica acta》1980,44(11):1701-1708

The sorption on humic acid (HA) of metals from an aqueous solution containing Hg(II). Fe(III), Pb, Cu, Al, Ni, Cr(III), Cd, Zn, Co and Mn, was investigated with special emphasis on effects of pH, metal concentration and HA concentration. The sorption efficiency tended to increase with rise in pH, decrease in metal concentration and increase in HA concentration of the equilibrating solution. At pH 2.4. the order of sorption was: Hg? Fe? Pb? CuAl ? Ni ? CrZnCdCoMn. At pH 3.7. the order was: Hg and Fe were always most readily removed, while Co and Mn were sorbed least readily. There were indications of competition for active sites (CO₂H and phenolic OH groups) on the HA between the different metals. We were unable to find correlations between the affinities of the eleven metals to sorb on HA and their atomic weights, atomic numbers, valencies, and crystal and hydrated ionic radii. The sorption of the eleven metals on the HA could be described by the equation $\text{Y =}\text{100}\text{[1 + exp ? (A + BX)]}$, where Y = % metal removed by HA; X = mgHA; and A and B are empirical constants.  相似文献   

Multiple metal ion exchange equilibria with humic acid     

Donald S. Gamble  M. Schnitzer  H. Kerndorff  C.H. Langford 《Geochimica et cosmochimica acta》1983,47(7):1311-1323

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Zur Problematik der Schwermineralanalyse am Beispiel triassischer Sedimentgesteine     

Prof. Dr. Walter A. Schnitzer 《International Journal of Earth Sciences》1983,72(1):67-75

The heavy mineral assoziations, extracted by the gravitative seperation, differ very much concerning to the density of the heavy liquid and the time of separation. There can be a difference up to 40 % for individual minerals at the same sample. A preceding treatment of the samples with acid, H₂O₂ etc. also has a great influence of the percentage of the minerals in the assoziations. Samples, gravitative seperated, and such seperated by centrifuge cannot be compared. The reason is not known up to now, but obviously the different wettability of the individual minerals is of great importance. In the futur in publications you should specify the density of the heavy liquid, the time of separation, preceding treatment etc. Otherwise you will never be able to compare or reproduce results. These problems are discussed by means of investigated sandstones of the Trias in Northern Bavaria.  相似文献   

Nitrogen distribution as a function of radiocarbon age in Paleosol humic acids     

G. Calderoni  M. Schnitzer 《Organic Geochemistry》1984,5(4):203-209

Humic acids were extracted from six Paleosols (buried soils), ranging in radiocarbon ages from about 6000 to 29,000 yr. The N distribution (total N, amino acid-N, amino sugar-N, ammonia-N and “unknown” N) in each Paleosol humic acid was determined. After 6 M HCl hydrolysis, amino acid-N and ammonia-N decreased with increasing age but relative concentrations of “unknown” N increased. Aspartic acid, valine and serine were the most stable amino acids. Concentrations of amino sugars were very small, with concentrations of galactosamine exceeding those of glucosamine. The data showed that with increasing age, identifiable N components were converted to complex polymeric compounds whose identities still remain unknown. The different N-forms in HA's of geological times are valuable geochemical markers which provide useful information on the history of these soils.  相似文献   

Effects of age on the chemical structure of paleosol humic acids and fulvic acids     

Gilberto Calderoni  Morris Schnitzer 《Geochimica et cosmochimica acta》1984,48(10):2045-2051

Humic acids and fulvic acids were extracted from six paleosols in Southern Italy. Humic acids (HAs) constituted between 96.5 and 99.2% of the total extracts; the remaining materials consisted of fulvic acids (FAs). Radiocarbon ages of the HAs ranged from about 6,000 to close to 29,000 years B.P., δ¹³C values averaged $\text{?25.6 ± 0.3‰}$ The HAs were characterized by chemical (elemental and functional group analyses) and spectroscopic (IR, ESR, ¹³CNMR, E₄/E₆ ratios) methods. FAs were characterized by chemical methods, E₄/E₆ ratios and IR spectra.The chemical and spectroscopic analyses showed practically no differences in the chemical structure and composition of the six HAs and FAs, so that age appeared to have little effect on these parameters. The paleosols were found to be closed systems with low polysaccharide and protein contents, thus providing unfavorable substrates for microbial activity. The preservation of the humic materials in the paleosols may have been due to low biological activity and/or to retention by amorphous minerals. The HAs did not appear to be affected by temperatures higher than 170–200°C over the 23,000 year period which we observed.  相似文献   

PRIMARILY STUDY ON FEATURES OF SURFACE RUPTURES INDUCED BY THE 2016 M_W7.8 KARKOURA EARTHQUAKE,NEW ZEALAND          下载免费PDF全文

HAN Zhu-jun  Nicola Litchfield  RAN Hong-liu  YUAN Ren-mao  GUO Peng  Robert M Langridge  Russ J Van Dissen 《地震地质》2017,39(4):675-688

The surface ruptures produced by the 2016 M_W7.8 Karkoura earthquake, New Zealand are distributed in a belt with~170km long and~35km wide, trending generally in the NE-SW direction. There are at least 12 faults on which meter-scale displacements are identified and they were formed across two distinct seismotectonic provinces with fundamental different characteristics(Hamling et al., 2017; Litchfield et al., 2017). Although the trending directions of the seismic surface ruptures vary greatly at different locations, the ruptured faults can be generally divided into two groups with the NE to NEE direction and the NNW to N direction, respectively. The faults in the NNW-near NS direction are nearly parallel with 40~50km apart and featured by reverse movement with the maximum displacement of 5~6m. The faults in the NE-NNE direction, with the maximum of 25~30km apart are not continuous and featured by the dextral strike slip with the largest displacement of 10~12m. Even if some faults along the NE-NEE direction are end to end connected, their strikes differ by about 30°. The combination styles of the strike-slip fault surface ruptures along the NE-NEE direction can be merged into 3 categories, including en-echelon, bifurcation and parallel patterns. The scales of the fault surface ruptures with the same structural style could be obviously different in different areas, which results in significant changes in the widths of deformation zone, from tens of meters to hundreds of meters. En-echelon distributed surface rupture(section)can appear as a combination belt of meter-scale to dozens of meter-scale shear fracture with bulge and compressional shear fractures, and also can be characterized by the combination of the left-step en-echelon tensile shear fractures with a length of more than one hundred meters. The step-overs between surface rupture sections are clearly different in sizes, which can be dozens of meters, hundreds of meters to several kilometers. The spacing between parallel surface ruptures can be several meters, dozens of meters to several kilometers. Besides, as one of the prominent characteristics, the seismic surface ruptures caused by the Karkoura earthquake broke through the known distribution pattern of active faults. The surface ruptures can occur either on the previously thought inactive or unmapped faults, or break through the distribution range of previously realized active faults in the striking or lateral direction. The basic features about the distribution and widths of the surface ruptures induced by the 2016 M_W7.8 Karkoura earthquake, New Zealand presented in this paper might be helpful for understanding some seismic problems such as complex corresponding relationship between the active faults and the deep seismogenic structure, and the necessary measurements for engineering crossing active faults.  相似文献   

A survey of Earth strain tides in Great Britain     

Russ Evans  John Beavan  Roger Bilham  Geoffrey King 《Geophysical Journal International》1979,57(1):119-135

Summary . We report 35 measurements of Earth strain tides at 16 near-surface sites in Great Britain. This is the first widespread survey undertaken specifically to examine the problem of the inhomogeneity of elastic strain fields near the Earth's surface. Some sites were instrumented intensively in order to examine variations of tidal admittance over distances of several hundred metres, while measurements from single instruments at other sites were compared with theoretically predicted strain tides. After allowing for cavity and topographic effects, our data show variations of up to 50 per cent in tidal admittance. We interpret such large anomalies as being due to variations in the regional elastic parameters of wavelength about a 100 m or less. The data indicate that strain measurements from single instrument sites must be interpreted with caution.  相似文献