Large-Scale Errors in ERS Altimeter Data

A method is described for mapping time-uncorrelated large-scale errors in satellite altimeter sea surface heights. Standard deviations of differences between pairs of successive measurements at track crossovers are computed, and the functional dependence of these deviations on absolute time difference is used to estimate the errors of individual measurements. This is first applied to all of ERS-1,2 altimeter data in the Pacific Ocean, yielding average errors of 3.2 cm in the deep ocean (>1 km) and 4.7 cm in the shallow seas (<1 km). The procedure is repeated for variable latitude bands, each with a full range of possible time differences, yielding a meridional profile of computed errors, ranging from 2.6 cm near the Antarctic continent (67–60S) and South Subtropical regions (25–5S) to 3.5 cm in the Antarctic Circumpolar Current (60–45S) and the Northern Hemisphere Subtropical and Subpolar Gyres. Finally, coarse-resolution maps of these errors are produced by subdividing the Pacific Ocean into latitude-longitude bins, each large enough to contain a sufficient number of samples for the functional fits. The larger errors are in Northwest and Subtropical Pacific, especially in South China Sea (4.3 to 4.5 cm) and off northern Australia (5.4 cm), while the smaller errors (2.5 to 3 cm) are in Northeast Pacific, central Tropical Pacific and near Antarctica in Southeast Pacific Ocean. These are lower bounds on altimeter errors, as they do not include contributions from time-correlated errors. We find that the computed error fields are not correlated with sea level standard deviations, thus disproving the notion that altimeter error variance can be scaled with the variance of sea surface height data.     

On computing ellipsoidal harmonics using Jekeli’s renormalization

Gravity data observed on or reduced to the ellipsoid are preferably represented using ellipsoidal harmonics instead of spherical harmonics. Ellipsoidal harmonics, however, are difficult to use in practice because the computation of the associated Legendre functions of the second kind that occur in the ellipsoidal harmonic expansions is not straightforward. Jekeli’s renormalization simplifies the computation of the associated Legendre functions. We extended the direct computation of these functions—as well as that of their ratio—up to the second derivatives and minimized the number of required recurrences by a suitable hypergeometric transformation. Compared with the original Jekeli’s renormalization the associated Legendre differential equation is fulfilled up to much higher degrees and orders for our optimized recurrences. The derived functions were tested by comparing functionals of the gravitational potential computed with both ellipsoidal and spherical harmonic syntheses. As an input, the high resolution global gravity field model EGM2008 was used. The relative agreement we found between the results of ellipsoidal and spherical syntheses is 10^?14, 10^?12 and 10^?8 for the potential and its first and second derivatives, respectively. Using the original renormalization, this agreement is 10^?12, 10^?8 and 10^?5, respectively. In addition, our optimized recurrences require less computation time as the number of required terms for the hypergeometric functions is less.     

Occurrence of synthetic musk compounds in surface,underground, waste and processed water samples in Belgrade,Serbia

This study assessed the state of waters in Belgrade regarding pollution with musk compounds as the target contaminants. Eleven of these compounds were alicyclic, two were macrocyclic, and one was polycyclic. Solid-phase microextraction was used for the isolation of these compounds from waste, surface and underground waters and from processed water prepared for drinking, while comprehensive orthogonal two-dimensional gas chromatography with mass spectrometry was used as the final analytical method. In wastewater samples, galaxolide was detected in concentrations of 1.13 and 0.40 μg/L, while in the Sava River and underground water its concentrations were 0.09 and 0.038 μg/L. The lowest concentrations of the investigated musk compounds were detected in underground water samples, indicating that this is the cleanest water of all the analyzed sources with respect to musk compounds. Comparing the results of musk compound concentrations determined in surface river water samples and clean river water samples utilized for drinking, a lower concentration of these compounds was detected in the clean river water samples. The majority of musk compounds were found in waters utilized for drinking. Based on the concentration values, we conclude that the analyzed waters are moderately polluted with these compounds.     

Über ein geregeltes Magnesitgefüge

Zusammenfassung Auf Grund der Gleichheit des c-Achsen-Diagramms von Magnesit mit synoptischen Diagrammen von Calcit und Dolomit-B-Tektoniten kann auch für Magnesit ein gleicher Translationsmechanismus mit Einregelung von in h01-Flächen angenommen werden.

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Summary On the basis of the equality of the c-axis diagram of magnesite with synoptic diagrams of B-tectonites of calcite and dolomite and identical mechanism of translation with preferred orientation of in h01-planes can be assumed.

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Mit 1 Textabbildung und 3 Gefügediagrammen im Text

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Herrn Professor Dr.F. Machatschki zum 70. Geburtstag gewidmet.     

Non—integrability of Hill's lunar problem

We prove that Hill's lunar problem does not possess a second analytic integral of motion, independent of the Hamiltonian. In order to obtain this result, we avoid the usual normalization in which the angular velocity of the rotating reference frame is put equal to unit. We construct an artificial Hamiltonian that includes an arbitrary parameter b and show that this Hamiltonian does not possess an analytic integral of motion for in an open interval around zero. Then, by selecting suitable values of , b and using the invariance of the Hamiltonian under scaling in the units of length and time, we show that the Hamiltonian of Hill's problem does not possess an integral of motion, analytically continued from the integrable two–body problem in a rotating frame.     

A Comparative Analysis of Favorability Mappings by Weights of Evidence,Probabilistic Neural Networks,Discriminant Analysis,and Logistic Regression

This study compares the performance of favorability mappings by weights of evidence (WOE), probabilistic neural networks (PNN), logistic regression (LR), and discriminant analysis (DA). Comparisons are made by an objective measure of performance that is based on statistical decision theory. The study further emphasizes out-of-sample inference, and quantifies the extent to which outcome is influenced by optimum variable discretization with classification and regression trees (CARTS).Favorability mapping methodologies are evaluated systematically across three case studies with contrasting scale and geologic information:

Non-hydrostatic model of airflow over irregular topography. Numerical experiment

Summary In this study a non-hydrostatic anelastic model, the theoretical basis of which was described in a previous study, is presented. The results of four computer experiments used for simulating the flow of neutrally and stably stratified air over irregular topography are shown and discussed. The impact of spatial boundary conditions on the resulting fields is also discussed.