Absolute Calibration of the TOPEX/POSEIDON Altimeters using UK Tide Gauges, GPS, and Precise, Local Geoid-Differences   总被引：2，自引：0，他引：2  

Xiaojun Dong  Philip Woodworth  Philip Moore  Richard Bingley 《Marine Geodesy》2002,25(3):189-204

This article describes an "absolute" calibration of TOPEX/POSEIDON (T/P) altimeter bias using UK tide gauges equipped with Global Positioning System (GPS) receivers. The method is an extension of earlier work using the Newhaven tide gauge in the English Channel. However, the present analysis extends the research to a number of gauges around the UK and incorporates several improvements. The time-averaged TOPEX and POSEIDON biases are obtained with a precision of approximately 2 and 3 cm, respectively. The research complements work on bias determination by other groups in the T/P Science Working Team and can, in principle, be applied at other locations for which precise, local geoid-differences are available. The relatively sparse POSEIDON data set has been used as a test of our ability to perform an absolute calibration of upcoming Jason-1 altimetry as soon as possible after launch.  相似文献   

Ra and Ra in the mixing zones of the Pee Dee River-Winyah Bay, Yangtze River and Delaware Bay Estuaries     

Robert J. Elsinger  Willard S. Moore 《Estuarine, Coastal and Shelf Science》1984,18(6)

²²⁶Ra and ²²⁸Ra have non-conservative excess concentrations in the mixing zones of the Pee Dee River-Winyah Bay estuary, the Yangtze River estuary, and the Delaware Bay estuary. Laboratory experiments, using Pee Dee River sediment, indicate desorption of ²²⁶Ra to increase with increasing salinities up to 20‰. In Winyah Bay desorption from river-borne sediments could contribute almost all of the increases for both isotopes. Desorption adds only a portion of the excess ²²⁸Ra measured in the Yangtse River and adjacent Shelf waters and Delaware Bay. In the Yangtze River the mixing zone extends over a considerable portion of the Continental Shelf where ²²⁸Ra is added to the water column by diffusion from bottom sediments, while ²²⁶Ra concentrations decrease from dilution. Diffusion of ²²⁸Ra from bottom sediments in Delaware Bay primarily occurs in the upper part of the bay (< 22‰ water) where fine grained sediments predominate. A diffusive flux for ²²⁸Ra of 0·33 dpm cm⁻² year was determined for Delaware Bay.  相似文献   

Submarine groundwater discharge: A large, previously unrecognized source of dissolved iron to the South Atlantic Ocean   总被引：4，自引：5，他引：4  

Herbert L. Windom  Willard S. Moore  L. Felipe H. Niencheski  Richard A. Jahnke   《Marine Chemistry》2006,102(3-4):252-266

This paper reports the initial results of a study of groundwater and coastal waters of southern Brazil adjacent to a 240 km barrier spit separating the Patos Lagoon, the largest coastal lagoon in South America, from the South Atlantic Ocean. The objective of this research is to assess the chemical alteration of freshwater and freshwater–seawater mixtures advecting through coastal permeable sands, and the influence of the submarine discharge of these fluids (SGD) on the chemistry of coastal waters. Here we focus on dissolved iron in this system and use radium isotopic tracers to quantify SGD and cross-shelf fluxes. Iron concentrations in groundwaters vary between 0.6 and 180 μM. The influence of the submarine discharge of these fluids into the surf zone produces dissolved Fe concentrations as high as several micromolar in coastal surface waters. The offshore gradient of dissolved Fe, coupled with results for Ra isotopes, is used to quantify the SGD flux of dissolved Fe from this coastline. We estimate the SGD flux to be 2 × 10⁶ mol day^− 1 and the cross-shelf flux to be 3.2 × 10⁵ mol day^− 1. This latter flux is equal to about 10% of the soluble atmospheric Fe flux to the entire South Atlantic Ocean. We speculate on the importance of this previously unrecognized iron input to regional ocean production and on the potential significance of this source to understanding variations in glacial–interglacial ocean production.  相似文献   

A carbon and nitrogen flux model of mussel digestive gland epithelial cells and their simulated response to pollutants     

McVeigh A  Allen JI  Moore MN  Dyke P  Noble D 《Marine environmental research》2004,58(2-5):821-827

The mussel digestive gland epithelial cells provide a key interface between the organism and pollutants such as aromatic hydrocarbons. The simulation of their uptake and export mechanisms as well as an internal protein degradation pathway, and any subsequent disruption to any of them, has been undertaken. A computational model is described, which simulates the flow of carbon and nitrogen through a mussel's digestive cell. The model uses a compartmentalised view of the cell with inviolate 'pipelines' connecting each of the volume-variable partitions. Only the major physiological pathways relevant to the flow of either carbon or nitrogen or volume are modelled. Simulated response to hydrocarbon exposure is examined.  相似文献   

Significance of metallothioneins and lysosomes in cadmium toxicity and homeostasis in the digestive gland cells of mussels exposed to the metal in presence or absence of phenanthrene     

A. Viarengo  M.N. Moore  G. Mancinelli  A. Mazzucotelli  R.K. Pipe 《Marine environmental research》1985,17(2-4)

Metallothioneins and lysosomes are known to be involved in cellular detoxication and sequestration of certain metals^1–3 and both have been identified in this role in elimination of copper from marine mussels (Mytilus edulis/galloprovincialis).³ Cadmium (Cd), however, has been shown to persist in the cells of the digestive gland for long periods with only minimal elimination. An experiment was designed to test the effects of Cd on the fragility of lysosomal membranes in the digestive cells as a measure of cellular injury,^4,5 metallothionein content of the digestive gland and cadmium concentration in this organ. Phenanthrene was used also to destabilise lysosomal membranes⁶ in order to test if increased lysosomal fragility interfered with cadmium metabolism and detoxication. The results demonstrated that Cd induced metallothionein synthesis and that elimination of Cd was minimal after 28 days in clear seawater. Lysosomal fragility was initially increased but this effect was soon reversed, even with continued exposure to Cd. The lysosomal destabiliser, phenanthrene, did not appear to affect accumulation of Cd or levels of metallothionein.  相似文献   

Histopathological effects induced in Mytilus edulis by Mytilicola intestinalis and the histochemistry of the copepod intestinal cells     

Moore  M. N.; Lowe  D. M.; Gee  J. M. 《ICES Journal of Marine Science》1978,38(1):6-11

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Lysosomal reaction to xenobiotics in mussel hemocytes using BODIPY-FL-verapamil     

M. N. Moore  R. J. Wedderburn  D. M. Lowe  M. H. Depledge 《Marine environmental research》1996,42(1-4)

Many cellular and sub-cellular biomarkers associated with mussel (Mytilus edulis) digestive gland and kidney have been characterised. The lysosomal compartment of these tissues have been recognised as being particularly sensitive, exhibiting pollutant induced responses which could be potentially used as a ‘biomarker’. However, relatively few studies have investigated the lysosomal response within molluscan hemocytes. This study was conducted to test whether lysosomal reactions, in live hemocytes isolated from mussels, can be used as a biomarker of pollutant exposure and deleterious effect. Lysosomal responses to a number of hydrocarbons, including anthracene and phenanthrene, and to the amphiphilic heterocylic chemical, chlorpromazine, were examined. The supravital dye neutral red (NR) was used to examine lysosomal membrane fragility, following xenobiotic exposure. NR was also used to verify the lysosomal compartment as the reported accumulation site of a new molecular probe, BODIPY-FL-verapamil (BFLV). The use of BFLV, with confocal laser microscopy and image analysis enabled visualisation and quantification of lysosomal distribution and perturbation. BFLV showed that exposure of molluscan hemocytes to xenobiotics (20 ppb–10 ppm) induced the formation of pathologically enlarged lysosomes. The internal trafficking of lysosomes was shown to be severely compromised after exposure to chlorpromazine. Exposed molluscan hemocytes exhibited significantly reduced lysosomal retention times, for neutral red. Preliminary data is presented demonstrating the opportunity for these non-destructive biomarker techniques to detect pollution gradients in situ.  相似文献   

Heating and cooling of the thermal X-ray plasma in solar flares     

Ronald L. Moore  Dayton W. Datlowe 《Solar physics》1975,43(1):189-209

Characteristic times for heating and cooling of the thermal X-ray plasma in solar flares are estimated from the time profile of the thermal X-ray burst and from the temperature, emission measure and over-all length scale of the flare-heated plasma at thermal X-ray maximum. The heating is assumed to be due to magnetic field reconnection, and the cooling is assumed to be due to heat conduction and radiation. Temperatures and emission measures derived from UCSD OSO-7 X-ray flare observations are used, and length scales are obtained from Big Bear large-scale Hα filtergrams for 17 small (subflare to Class 1) flares. The empirical values obtained for the characteristic times imply (1) that flares are produced by magnetic field reconnection, (2) that conduction cooling of the thermal X-ray plasma dominates radiative cooling and (3) that reconnection heating and conduction cooling of the thermal X-ray plasma are approximately in balance at thermal X-ray maximum. This model in combination with the data gives estimates for the electron number density (10¹⁰–10¹¹ cm^?3) and the magnetic field strength (10–100 G) in the thermal X-ray plasma and for the total thermal energy generated in a subflare (≈ 10³⁰ erg for an Hα area ≈ 1 square degree) which agree with previous observational and theoretical estimates obtained by others.  相似文献   

Automatic solar image motion measurements     

Stirling A. Colgate  Elliott P. Moore 《Solar physics》1975,41(2):487-498

The solar seeing image motion has been monitored electronically and absolutely with a 25 cm telescope at three sites along the ridge at the southern end of the Magdalena Mountains west of Socorro, New Mexico. The uncorrelated component of the variations of the optical flux from two points at opposite limbs of the solar disk was continually monitored in 3 frequencies centred at 0.3, 3 and 30 Hz. The frequency band of maximum signal centred at 3 Hz showed the average absolute value of image motion to be somewhat less than 2 although wide variations from 20 to an extraordinarily quiet day of less than the measurement limit of 1/2 were observed. The observer estimates of combined blurring and image motion were well correlated with electronically measured image motion, but the observer estimates gave a larger value × 2 presumable because the electronic measurement gave only the uncorrelated motion of opposite limbs. Approximately 30% of the total solar time would allow spatial position measurements of solar features to a precision 2 and, from the visual estimates, blurring limited measurements to a precision 4.  相似文献   

X-ray and Hα observations of a filament-disappearance flare: An empirical analysis of the magnetic field configuration     

S. W. Kahler  D. F. Webb  R. L. Moore 《Solar physics》1981,70(2):335-350

A flare event occurred which involved the disappearance of a filament near central meridian on 29 August 1973. The event was well observed in X-rays with the AS & E telescope on Skylab and in H at BBSO. It was a four-ribbon flare involving both new and old magnetic inversion lines which were roughly parallel. The H, X-ray, and magnetic field data are used to deduce the magnetic polarities of the H brightenings at the footpoints of the brightest X-ray loops. These magnetic structures and the preflare history of the region are then used to argue that the event involved a reconnection of magnetic field lines rather than a brightening in place of pre-existing loops. The simultaneity of the H brightening onsets in the four ribbons and the apparent lack of an eruption of the filament are consistent with this interpretation. These observations are compared to other studies of filament disappearances. The preflare structures and the alignment of the early X-ray flare loops with the H filament are consistent with the schematic picture of a filament presented first by Canfield et al. (1974).  相似文献