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  • 1
    Electronic Resource
    Electronic Resource
    Separation of liquid mixtures by using polymer membranes, V. Water-alcohol separation by pervaporation through poly(vinyl alcohol)-graft-poly(styrene-co-maleic anhydride) membranes (1994)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 219 (1994), S. 169-184 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Styrol/Maleinsäureanhydrid-Copolymeres (ST-co-MA), hergestellt aus Styrol und Maleinsäureanhydrid in Dimethylsulfoxid mit Azoisobutyronitril als Initiator, wurde durch eine Kondensationsreaktion auf Poly(vinylalkohol) (PVA) gepfropft. Die Strukturen der Produkte wurden mittels IR-Spektroskopie untersucht. Die Abhängigkeit der Pfropfterpolymerzusammensetzung, -viskosität und -ausbeute von der Konzentration der Reaktanden sowie die mechanischen Eigenschen von aus den Pfropfprodukten hergestellten Membranen wurden ermittelt. Bei der Untersuchung der Permeationseigenschaften zeigte sich, daß die Membranen bei allen Zusammensetzungen von Alkohol/Wasser-Gemischen bevorzugt für Wasser durchlässig sind. Mit steigendem PVA-Anteil in den Membranen und wachsendem Ethanolanteil der Alkohol/Wasser-Mischung nimmt die Durchlässigkeit ab und die Selektivität zu. Weiterhin wird der Einfluß der Größe der permeierenden Moleküle auf die Durchlässigkeit und Trenneigenschaften diskutiert.
    Notes: Graft copolymerization of styrene-maleic anhydride copolymer (ST-co-MA) onto poly(vinyl alcohol) (PVA) was carried out by a condensation-coupling reaction through esterification. The ST-co-MA copolymer was obtained by the copolymerization of MA and ST in dimethyl sulfoxide (DMSO), using azoisobutyronitrile as initiator. The structure of the reaction products was confirmed by infrared analysis. The dependence of composition, viscosity and yield of the graft terpolymers on the concentration of the reactants are presented in detail. Mechanical properties of membranes with different compositions were measured over a wide range of composition. It was found that water was permeated through the membranes preferentially in all ranges of feed compositions. The permeation decreased and the selectivity increased with increasing ethanol concentration in the feed and with increasing PVA content in the membrane. The effect of the molecular size of the permeating species on both permeation and separation is also discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1994.052190114
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  • 2
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    The IERS Special Bureau for the Oceans (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The oceans have a major impact on global geophysical processes of the Earth. Non-tidal changes in oceanic currents and ocean-bottom pressure have been shown to be a major source of polar motion excitation and also measurably change the length of the day. The changing mass distribution of the oceans causes the Earth's gravitational field to change and causes the center-of-mass of the oceans to change which in turn causes the center-of-mass of the solid Earth to change. The changing mass distribution of the oceans also changes the load on the oceanic crust, thereby affecting both the vertical and horizontal position of observing stations located near the oceans. Recognizing the important role that non-tidal oceanic processes play in Earth rotation dynamics and terrestrial reference frame definition, the International Earth Rotation Service has recently created a Special Bureau for the Oceans in order to facilitate research into these and other solid Earth geophysical processes affected by the oceans.
    Keywords: Oceanography
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  • 3
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    A Comparison Between the TOPEX/POSEIDON Data and a Global Ocean General Circulation (1995)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: The TOPEX/POSEIDON altimetric sea level observation during 1992-93 was used to validate the.
    Keywords: Oceanography
    Type: Journal of Geophysical Research - Oceans
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  • 4
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    Towards Estimating Global Ocean Circulation Combining TOPEX/Poseidon altimeter Data and an Ocean General Circulation Model (1995)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Oceanography
    Type: Towards Estimating Global Ocean Circulation Combining TOPEX/Poseidon altimeter Data and an Ocean General Circulation Model, International Association for the Physical Sciences of the Oceans
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  • 5
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    A Three-Dimensional Variational Data Assimilation Scheme for the Regional Ocean Modeling System: Implementation and Basic Experiments (2008)
    In:  Other Sources
    Details
    Publication Date: 2018-06-11
    Description: A three-dimensional variational data assimilation scheme for the Regional Ocean Modeling System (ROMS), named ROMS3DVAR, has been described in the work of Li et al. (2008). In this paper, ROMS3DVAR is applied to the central California coastal region, an area characterized by inhomogeneity and anisotropy, as well as by dynamically unbalanced flows. A method for estimating the model error variances from limited observations is presented, and the construction of the inhomogeneous and anisotropic error correlations based on the Kronecker product is demonstrated. A set of single observation experiments illustrates the inhomogeneous and anisotropic error correlations and weak dynamic constraints used. Results are presented from the assimilation of data gathered during the Autonomous Ocean Sampling Network (AOSN) experiment during August 2003. The results show that ROMS3DVAR is capable of reproducing complex flows associated with upwelling and relaxation, as well as the rapid transitions between them. Some difficulties encountered during the experiment are also discussed.
    Keywords: Oceanography
    Type: Journal Of Geophysical Research; Volume 113
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  • 6
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    Global monitoring of Sea Surface Salinity with Aquarius (2005)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: Aquarius is a microwave remote sensing system designed to obtain global maps of the surface salinity field of the oceans from space. It will be flown on the Aquarius/SAC-D mission, a partnership between the USA (NASA) and Argentina (CONAE) with launch scheduled for late in 2008. The objective of Aquarius is to monitor the seasonal and interannual variation of the large scale features of the surface salinity field in the open ocean. This will provide data to address scientific questions associated with ocean circulation and its impact on climate. For example, salinity is needed to understand the large scale thermohaline circulation, driven by buoyancy, which moves large masses of water and heat around the globe. Of the two variables that determine buoyancy (salinity and temperature), temperature is already being monitored. Salinity is the missing variable needed to understand this circulation. Salinity also has an important role in energy exchange between the ocean and atmosphere, for example in the development of fresh water lenses (buoyant water that forms stable layers and insulates water below from the atmosphere) which alter the air-sea coupling. Aquarius is a combination radiometer and scatterometer (radar) operating at L-band (1.413 GHz for the radiometer and 1.26 GHz for the scatterometer). The primary instrument,for measuring salinity is the radiometer which is able to detect salinity because of the modulation salinity produces on the thermal emission from sea water. This change is detectable at the long wavelength end of the microwave spectrum. The scatterometer will provide a correction for surface roughness (waves) which is one of the greatest unknowns in the retrieval. The sensor will be in a sun-synchronous orbit at about 650 km with equatorial crossings of 6am/6pm. The antenna for these two instruments is a 3 meter offset fed reflector with three feeds arranged in pushbroom fashion looking away from the sun toward the shadow side of the orbit to minimize sunglint. The mission goal is to produce maps of the salinity field globally once each month with an accuracy of 0.2 psu and a spatial resolution of 100 km. This will be adequate to address l&ge scale features of the salinity field of the open ocean. The temporal resolution is sufficient to address seasonal changes and a three year mission is planned to-collect sufficient data to look for interannual variation. Aquarius is being developed by NASA as part of the Earth System Science Pathfinder (ESSP) program. The SAC-D mission is being developed by CONAE and will include the space craft and several additional instruments, including visible and infrared cameras and a microwave radiometer to monitor rain and wind velocity over the oceans, and sea ice.
    Keywords: Oceanography
    Type: URSI General Assembly Meeting; Oct 23, 2005 - Oct 29, 2005; Dehli; India
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  • 7
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    Comparison of tropical pacific temperature and current simulations with two vertical mixing schemes embedded in an ocean general circulation model and reference to observations (1995)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The Pacanowski-Philander (PP) and Mellor-Yamada (MY) parameterization models of vertical mixing by turbulent processes were embedded in the Geophysical Fluid Dynamics Laboratory high-resolution ocean general circulation model of the tropical Pacific Ocean. All other facets of the numerical simulations were the same. Simulations were made for the 1987-1988 period. At the equator the MY simulation produced near-surface temperatures more uniform with depth, a deeper thermocline, a deeper core speed of the Equatorial Undercurrent, and a South Equatorial Current with greater vertical thickness compared with that computed with the PP method. Along 140 deg W, between 5 deg N and 10 deg N, both simulations were the same. Moored buoy current and temperature observations had been recorded by the Pacific Marine Environmental Laboratory at three sites (165 deg E, 140 deg W, 110 deg W) along the equator and at three sites (5 deg N, 7 deg N, 9 deg N) along 140 deg W. Simulated temperatures were lower than those observed in the near-surface layer and higher than those observed in the thermocline. Temperature simulations were in better agreement with observations compared to current simulations. At the equator, PP current and temperature simulations were more representative of the observations than MY simulations.
    Keywords: OCEANOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 100; C2; p. 2515-2522
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  • 8
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    A Comparison between the TOPEX/POSEIDON Data and a Global Ocean General Circulation Model during 1992-1993 (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-08-15
    Description: The TOPEX/POSEIDON altimetric sea level observation during 1992-1993 was used to validate the simulation made by a global ocean general circulation model (OGCM) forced by the daily wind stress and heat flux derived from the National Meteorological Center operational analysis. The OGCM is a version of the modular ocean model with a horizontal resolution of 2 deg longitude and 1 deg latitude and 22 levels in the vertical. The model simulation is compared to the observation at spatial scales of the order of 500 km and larger. Only the temporal variations are examined. The variability is composed primarily of the annual cycle and intraseasonal fluctuations (periods shorter than 100 days). The basic features of the annual cycle are simulated well by the model. Major discrepancies are found in the eastern tropical Pacific, as well as the eastern North Pacific and most of the interior of the North Atlantic. The culprit is suspected to be the inadequate heat forcing and mixing parameterizations of the model. Significant intraseasonal variability is found in the central North Pacific and the Southern Ocean. The simulation is highly correlated with the observation at periods from 20 to 100 days. The spatial scales are larger than 1000 km in many places. These variabilities are apparently the barotropic response of the ocean to wind forcing. The results of the study provide a basis for future assimilation of the data into the OGCM for improved description of the large-scale ocean variabilities.
    Keywords: Oceanography
    Type: Paper 95JC02260 , Journal of Geophysical Research (ISSN 0148-0227); 100; C12; 24,965-24,976
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  • 9
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    On the structure of the Southern Oscillation (1993)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A realistic oceanic general circulation model is forced with winds observed over the tropical Pacific between 1967 and 1979. The structure of the simulated Southern Oscillation is strikingly different in the western and eastern sides of the basin, because the principal interannual zonal-wind fluctuations are confined to the west and are in the form of an equatorial jet. This causes thermocline displacements to have maxima off the equator in the west (where the curl of the wind is large) but on the equator in the east. Zonal phase propagation, both on and off the equator, is at different speeds in the west and east. The phase pattern is complex, and there is, on interannual time scale, no explicit evidence of individual equatorial waves. These results lead to a modification of the 'delayed oscillator' mechanism originally proposed by Schopf and Suarez to explain a continual Southern Oscillation. The results also permit an evaluation of the various coupled ocean-atmosphere models that simulate the Southern Oscillation and indicate which measurements are necessary to determine which models are most relevant to reality.
    Keywords: OCEANOGRAPHY
    Type: Journal of Climate (ISSN 0894-8755); 6; 3; p. 450-469.
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  • 10
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    Sea surface height variability during 1986-1988 in the tropical Pacific Ocean (1993)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A description of the sea surface height variabilities during 1986-1988 in the tropical Pacific Ocean is presented on the basis of Geosat altimeter data and a tropical Pacific Ocean GCM (OGCM) forced with observed winds from Florida State University. Both data sets are validated against in situ sea-level measurements at 12 selected sea-level stations in the equatorial Pacific and were found to be in good agreement with these measurements with correlation coefficients of 0.69 for Geosat and 0.71 for OGCM. The Geosat altimeter data are capable of describing sea surface height variabilities during 1986-1988 in the tropical Pacific, in particular, the seasonal cycle, the 1987 El Nino and 1988 La Nina episodes, and the December 1986 equatorial Kelvin wave event. The OGCM-simulated surface dynamic height is found to be sensitive to different surface wind products.
    Keywords: OCEANOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 98; C4; p. 6947-6959.
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