Levelling co-located GNSS and tide gauge stations using GNSS reflectometry     

Alvaro Santamaría-Gómez  Christopher Watson  Médéric Gravelle  Matt King  Guy Wöppelmann 《Journal of Geodesy》2015,89(3):241-258

  相似文献   

Monument-antenna effects on GPS coordinate time series with application to vertical rates in Antarctica     

Matt?A.?KingEmail author  Michael?Bevis  Terry?Wilson  Bjorn?Johns  Frederick?Blume 《Journal of Geodesy》2012,86(1):53-63

We examine the electromagnetic coupling of a GPS antenna–monument pair in terms of its simulated affect on long GPS coordinate time series. We focus on the Earth and Polar Observing System (POLENET) monument design widely deployed in Antarctica and Greenland in projects interested particularly in vertical velocities. We base our tests on an absolute robot calibration that included the top ~0.15 m of the monument and use simulations to assess its effect on site coordinate time series at eight representative POLENET sites in Antarctica over the period 2000.0–2011.0. We show that the neglect of this calibration would introduce mean coordinate bias, and most importantly for velocity estimation, coordinate noise which is highly sensitive to observation geometry and hence site location and observation period. Considering only sub-periods longer than 2.5 years, we show vertical site velocities may be biased by up to ±0.4 mm/year, and biases up to 0.2 mm/year may persist for observation spans of 8 years. Changing between uniform and elevation-dependent observation weighting alters the time series but does not remove the velocity biases, nor does ambiguity fixing. The effect on the horizontal coordinates is negligible. The ambiguities fixed series spectra show noise between flicker and random walk with near-white noise at the highest frequencies, with mean spectral indices (frequencies <20 cycles per year) of approximately −1.3 (uniform weighting) and −1.4 (elevation-dependent weighting). While the results are likely highly monument specific, they highlight the importance of accounting for monument effects when analysing vertical coordinate time series and velocities for the highest precision and accuracy geophysical studies.  相似文献   

The settler's plot: how stories take place in New Zealand – By Alex Calder     

Matt Henry 《New Zealand geographer》2012,68(1):71-72

  相似文献   

A relativistically smeared spectrum in the neutron star X-ray binary 4U 1705−44: looking at the inner accretion disc with X-ray spectroscopy     

T. Di Salvo  A. D'Aí  R. Iaria  L. Burderi  M. Dov&#;iak  V. Karas  G. Matt  A. Papitto  S. Piraino  A. Riggio  N. R. Robba  A. Santangelo 《Monthly notices of the Royal Astronomical Society》2009,398(4):2022-2027

Iron emission lines at 6.4–6.97 keV, identified with fluorescent Kα transitions, are among the strongest discrete features in the X-ray band. These are therefore one of the most powerful probes to infer the properties of the plasma in the innermost part of the accretion disc around a compact object. In this paper, we present a recent XMM–Newton observation of the X-ray burster 4U 1705−44, where we clearly detect a relativistically smeared iron line at about 6.7 keV, testifying with high statistical significance that the line profile is distorted by high-velocity motion in the accretion disc. As expected from disc reflection models, we also find a significant absorption edge at about 8.3 keV; this feature appears to be smeared, and is compatible with being produced in the same region where the iron line is produced. From the line profile, we derive the physical parameters of the inner accretion disc with large precision. The line is identified with the Kα transition of highly ionized iron, Fe  xxv , the inner disc radius is   R _in= 14 ± 2  R _g  (where R _g is the Gravitational radius,   GM / c ²  ), the emissivity dependence from the disc radius is   r ^{−2.27±0.08}  , the inclination angle with respect to the line of sight is   i = 39°± 1°  . Finally, the XMM–Newton spectrum shows evidences of other low-energy emission lines, which again appear broad and their profiles are compatible with being produced in the same region where the iron line is produced.  相似文献   

Newsprint Mills in Australia: A story of shifting optimum location     

Matt Bradshaw 《The Australian geographer》2001,32(2):241-257

The focus in this paper is on the shifting optimum location for a newsprint mill in Australia, factors influencing this shift, and the implications for a particular manufacturing site that is becoming increasingly outdated and out-of-place. Shipping times and schedules for high-volume, high-density tonnages of commodities such as newsprint have altered insufficiently over the last 60 years to affect competitive relations among various newsprint manufacturers around the world. With sea transport held roughly constant, changes in other aspects of the international newsprint industry can be investigated as part of unpacking the concept of globalisation. Globalisation for the former Australian Newsprint Mills Ltd meant becoming more open to new and closer competition, as well as becoming more exposed to acquisition by increasingly transnational enterprises. In the global newsprint industry at least, the world is less a smaller place than a more open one, with tonnes of newsprint moving at similar speeds to 60 years ago but among different and changing locations in terms of geography, ownership and market preference.  相似文献   

Zr and Nb partition coefficients: Implications for the genesis of mare basalts,KREEP and sea floor basalts     

I.S. McCallum  M.P. Charette 《Geochimica et cosmochimica acta》1978,42(6):859-869

  相似文献   

The impact of urban areas on the deposition of air toxics to adjacent surface waters: A mass budget of PCBs in Lake Michigan in 1994     

John Offenberg  Matt Simcik  Joel Baker  Steven J. Eisenreich 《Aquatic Sciences - Research Across Boundaries》2005,67(1):79-85

  相似文献   

Choice of optimal averaging radii for temporal GRACE gravity solutions, a comparison with GPS and satellite altimetry   总被引：3，自引：0，他引：3  

Matt King  Philip Moore  Peter Clarke    David Lavallée 《Geophysical Journal International》2006,166(1):1-11

  相似文献   

Paleomagnetism of Middle Proterozoic mafic intrusions and Upper Proterozoic (Nankoweap) red beds from the Lower Grand Canyon Supergroup, Arizona     

Arlo B. Weil  John W. Geissman  Matt Heizler  Rob Van der Voo 《Tectonophysics》2003,375(1-4):199

Paleomagnetic data from lavas and dikes of the Unkar igneous suite (16 sites) and sedimentary rocks of the Nankoweap Formation (7 sites), Grand Canyon Supergroup (GCSG), Arizona, provide two primary paleomagnetic poles for Laurentia for the latest Middle Proterozoic (ca. 1090 Ma) at 32°N, 185°E (dp=6.8°, DM=9.3°) and early Late Proterozoic (ca. 850–900 Ma) at 10°S, 163°E (dp=3.5°, DM=7.0°). A new ⁴⁰Ar/³⁹Ar age determination from an Unkar dike gives an interpreted intrusion age of about 1090 Ma, similar to previously reported geochronologic data for the Cardenas Basalts and associated intrusions. The paleomagnetic data show no evidence of any younger, middle Late Proterozoic tectonothermal event such as has been revealed in previous geochronologic studies of the Unkar igneous suite. The pole position for the Unkar Group Cardenas Basalts and related intrusions is in good agreement with other ca. 1100 Ma paleomagnetic poles from the Keweenawan midcontinent rift deposits and other SW Laurentia diabase intrusions. The close agreement in age and position of the Unkar intrusion (UI) pole with poles derived from rift related rocks from elsewhere in Laurentia indicates that mafic magmatism was essentially synchronous and widespread throughout Laurentia at ca. 1100 Ma, suggesting a large-scale continental magmatic event. The pole position for the Nankoweap Formation, which plots south of the Unkar mafic rocks, is consistent with a younger age of deposition, at about 900 to 850 Ma, than had previously been proposed. Consequently, the inferred 200 Ma difference in age between the Cardenas Basalts and overlying Nankoweap Formation provides evidence for a third major unconformity within the Grand Canyon sequence.  相似文献   

Reconstruction of urban stormwater contamination of an estuary using catchment history and sediment profile dating     

Andrew Swales  R. Bruce Williamson  Laurence F. Van Dam  Morag J. Stroud  Matt S. McGlone 《Estuaries and Coasts》2002,25(1):43-56

Cores were collected from the length of Pakuranga estuary, a small urban estuary in Auckland, New Zealand, to determine sedimentation and contaminant history, and in particular the impact of urbanization. Catchment sediment loads for the most recent history (1953–1995), including urbanization since 1960, were reconstructed using the landcover history and soil erosion modeling. Pollen and¹⁴C dating and pre-urban landcover history were used to reconstruct early estuary sedimentation (i.e., post-3000 yr BP to 1960). Heavy metal concentrations, particle size,¹³⁷Cs, pollen, and catchment sediment loads were all needed to disentangle the complex estuarine response to urbanization.¹³⁷Cs profiles did not reflect the historical fallout pattern, but deposition of¹³⁷Cs-labelled eroded catchment soil, coinciding with peaks in urban construction. Temporal variations in stormwater¹³⁷Cs concentrations are likely due to varying contributions from¹³⁷Cs-rich topsoil and¹³⁷Cs-poor subsoils. A similar pattern was observed in heavy-metal concentrations and attributed to street runoff rather than topsoil being diluted by metal-poor subsoils. Dating of the sediment profiles showed that during urbanization sedimentation rates in the tidal creek and estuary were higher than sedimentation rates associated with past agricultural landuse and the original forest landcover. Urbanization has brought about substantial environmental changes in the upper estuary through continued infilling of shallow, intertidal areas, contamination by heavy metals to levels of ecological concern, sediment textural changes, and rapid mangrove colonization of formerly bare intertidal sediments.  相似文献