Suspended sediment discharge of the Susquehanna river to Northern Chesapeake Bay, 1966 to 1976

Between 1966 and 1976, the Susquehanna River at Conowingo, Maryland, discharged approximately 50 million metric tons of suspended sediment to Northern Chesapeake Bay. About 40 million metric tons were discharged in two floods associated with hurricanes: Agnes (24–30 June 1972) and Eloise (26–30 September 1975). In the six years with complete records and no major floods, the Susquehanna River discharged 0.9±0.3 million metric tons of suspended sediment per year at Conowingo Dam. Aout 50 to 60 percent of the annual sediment discharge is usually floods, suspended sediment transport at Harrisburg, Pennsylvania, exceeds sediment discharge at Conowingo, Maryland, probably due to sediment deposition in the lower river and behind three hydroelectric dams.     

Cluster analysis of marine sediments and waste deposits in New York bight

Cluster analysis of some chemical characteristics of marine sediments and associated waste deposits in the New York Bight reveals the existence of four cluster facies. Cluster facies I is the sediment containing dredged wastes from New York Harbor. Cluster facies II is the widespread sand and gravel deposit of the continental shelf. Cluster facies III is the finergrained material in the Hudson Channel and the material accumulated in the sewage sludge disposal area. Cluster facies IV is not easily identified; it may correspond to some relict sedimentary feature in the area. Editor's Note: Ali is now with the Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543; Gross is now with Chesapeake Bay Institute. The Johns Hopkins University, Baltimore, Maryland 21218.     

Zum Umweltverhalten von Fluortensiden. Teil 2. Untersuchung der biochemischen Abbaubarkeit

In continuation of a publication on the behaviour of fluorotensides in aqueous solution there were tested four selected fluorotensides, among them a noniononic ethoxylated substance and three anion-active substances, in two different equipment with respect to their biochemical degradability. The BOD₅, the potassium permanganate consumption, the dry matter contents and the loss on ignition as well as the dehydrogenase test were used as parameters for judging the degradation behaviour. In all the four cases a high biochemical stability was found, so that they must be classified into the group C “biochemically not degradable or difficult to degrade” in agreement with the results found, according to the water pollutants catalogue.     

Physical Basis for Statistical Patterns in Complex Earthquake Populations: Models, Predictions and Tests

—Understanding the physics of earthquakes and the space-time patterns they produce is illuminated by the use of coarse-grained models and simulations that capture the basic physical processes, and that are amenable to analysis. We present a summary of ideas that describe the nucleation, growth, and arrest of earthquakes on individual faults. Under shear loading, we find that faults reside in a metastable state near a classical spinodal that governs the nucleation and growth of slip events. The roughness of an associated stress distribution field Σ(x, t) determines whether slip events are confined within the initial high stress patch, or break away and grow to become very large. We find a critical value of roughness that is associated with a first-order, "order–disorder" transition. We also give a number of predictions, examples and applications of these ideas, and indicate how they might be tested through systematic observational programs.     

Considerations concerning the non-rigid Earth nutation theory

This paper presents the reflections of the Working Group of which the tasks were to examine the non-rigid Earth nutation theory. To this aim, six different levels have been identified: Level 1 concerns the input model (giving profiles of the Earth's density and theological properties) for the calculation of the Earth's transfer function of Level 2; Level 2 concerns the integration inside the Earth in order to obtain the Earth's transfer function for the nutations at different frequencies; Level 3 concerns the rigid Earth nutations; Level 4 examines the convolution (products in the frequency domain) between the Earth's nutation transfer function obtained in Level 2, and the rigid Earth nutation (obtained in Level 3). This is for an Earth without ocean and atmosphere; Level 5 concerns the effects of the atmosphere and the oceans on the precession, obliquity rate, and nutations; Level 6 concerns the comparison with the VLBI observations, of the theoretical results obtained in Level 4, corrected for the effects obtained in Level 5.Each level is discussed at the state of the art of the developments.     

Latitudinal and longitudinal variation of a planetary atmosphere and the occultation experiment

The distribution of neutral and ionized particles about a planet depends, at any time, on angular coordinates (latitude and longitude) as well as altitude. Measurements of the Venusian and Martian atmospheres and ionospheres have been made by means of the ‘occultation’ experiment on-board the Mariner spacecrafts, and the same or similar experiment is planned for future missions to the planets. The conventional method of reducing the residual doppler data assumes spherical symmetry, in which the refractivity of the medium depends only on radius from the center of the planet, or altitude. It is shown that the neglect of angular dependence may introduce serious errors, even for media in which this dependence is slight compared to that in the radial direction, when the plane of motion of the spacecraft about the planet is inclined with respect to the direction of the Earth. The magnitude of the errors may be greatest for a planet such as Mercury and least for Jupiter, if planetary size and atmospheric temperature are the principal factors considered. Mars and Venus being intermediate. These results are most significant for an orbiter in which the orbital plane is inclined to obtain planetary coverage in a matter of months of measurements. Results of calculations for a particular model show that scale height measurements, and, thereby, atmospheric temperature, may be in error by a factor greater than 2 for inclined orbital configurations.     

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On the long-term stability of terrestrial reference frame solutions based on Kalman filtering

The Global Geodetic Observing System requirement for the long-term stability of the International Terrestrial Reference Frame is 0.1 mm/year, motivated by rigorous sea level studies. Furthermore, high-quality station velocities are of great importance for the prediction of future station coordinates, which are fundamental for several geodetic applications. In this study, we investigate the performance of predictions from very long baseline interferometry (VLBI) terrestrial reference frames (TRFs) based on Kalman filtering. The predictions are computed by extrapolating the deterministic part of the coordinate model. As observational data, we used over 4000 VLBI sessions between 1980 and the middle of 2016. In order to study the predictions, we computed VLBI TRF solutions only from the data until the end of 2013. The period of 2014 until 2016.5 was used to validate the predictions of the TRF solutions against the measured VLBI station coordinates. To assess the quality, we computed average WRMS values from the coordinate differences as well as from estimated Helmert transformation parameters, in particular, the scale. We found that the results significantly depend on the level of process noise used in the filter. While larger values of process noise allow the TRF station coordinates to more closely follow the input data (decrease in WRMS of about 45%), the TRF predictions exhibit larger deviations from the VLBI station coordinates after 2014 (WRMS increase of about 15%). On the other hand, lower levels of process noise improve the predictions, making them more similar to those of solutions without process noise. Furthermore, our investigations show that additionally estimating annual signals in the coordinates does not significantly impact the results. Finally, we computed TRF solutions mimicking a potential real-time TRF and found significant improvements over the other investigated solutions, all of which rely on extrapolating the coordinate model for their predictions, with WRMS reductions of almost 50%.