The status of measurement of the Mediterranean mean dynamic topography by geodetic techniques   总被引：1，自引：1，他引：0  

Philip L. Woodworth  Médéric Gravelle  Marta Marcos  Guy Wöppelmann  Chris W. Hughes 《Journal of Geodesy》2015,89(8):811-827

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Fine-Scale Characteristics of Temperature, Wind, and Turbulence in the Lower Atmosphere (0–1,300 m) Over the South Peruvian Coast     

Ben B. Balsley  Dale A. Lawrence  Ronald F. Woodman  David C. Fritts 《Boundary-Layer Meteorology》2013,147(1):165-178

We report results of preliminary high-resolution in situ atmospheric measurements through the boundary layer and lower atmosphere over the southern coast of Perú. This region of the coast is of particular interest because it lies adjacent to the northern coastal edge of the sub-tropical south-eastern Pacific, a very large area of ocean having a persistent stratus deck located just below the marine boundary layer (MBL) inversion. Typically, the boundary layer in this region during winter is topped by a quasi-permanent, well-defined, and very large temperature gradient. The data presented herein examine fine-scale details of the coastal atmosphere at a point where the edge of this MBL extends over the coastline as a result of persistent onshore flow. Atmospheric data were gathered using a recently-developed in-house constructed, GPS-controlled, micro-autonomous-vehicle aircraft (the DataHawk). Measured quantities include high-resolution profiles of temperature, wind, and turbulence structure from the surface to 1,300 m.  相似文献   

Quaternary glacial records in mountain regions：A formal stratigraphical approach     

P.D.Hughes P.L.Gibbard J.C.Woodward 《《幕》》2005,28(2):85-92

Glacial deposits in locally-glaciated mountain regions are often expressed through their surface form and the study of these deposits constitutes a major branch of geomorphology. Studies of glacial depositional records in mountain areas have often neglected formal stratigraphical procedure resulting in an ad hoc development of quasi-stratigraphical nomenclature. Here, a formal stratigraphical procedure is recommended, since this enables a systematic approach to the subdivision of glacial deposits in mountain regions. Moreover, such an approach facilitates, in some instances, the development of a formal chronostratigraphy that can be compared to regional and global geological time scales. This is important in locally-glaciated mountain regions where glacial deposits represent one of the most important records of cold stage environments. Given that glacial landforms represent a key component of the Quaternary record, maintaining a formal link between geomorphological and geological stratigraphical procedure is a fundamental requirement of a consistent and comparable stratigraphical framework.  相似文献   

Near-infrared laboratory spectra of solid H₂O/CO₂ and CH₃OH/CO₂ ice mixtures     

Max P. Bernstein  Dale P. Cruikshank  Scott A. Sandford 《Icarus》2005,179(2):527-534

We present near-IR spectra of solid CO₂ in H₂O and CH₃OH, and find they are significantly different from that of pure solid CO₂. Peaks not present in either pure H₂O or pure CO₂ spectra become evident when the two are mixed. First, the putative theoretically forbidden CO₂ (2ν₃) overtone near 2.134 μm (4685 cm⁻¹), that is absent from our spectrum of pure solid CO₂, is prominent in the spectra of H₂O/CO₂=5 and 25 mixtures. Second, a 2.74-μm (3650 cm⁻¹) dangling OH feature of H₂O (and a potentially related peak at 1.89 μm) appear in the spectra of CO₂-H₂O ice mixtures, but are probably not diagnostic of the presence of CO₂. Other CO₂ peaks display shifts in position and increased width because of intermolecular interactions with H₂O. Warming causes some peak positions and profiles in the spectrum of a H₂O/CO₂=5 mixture to take on the appearance of pure CO₂. Absolute strengths for absorptions of CO₂ in solid H₂O are estimated. Similar results are observed for CO₂ in solid CH₃OH. Since the CO₂ (2ν₃) overtone near 2.134 μm (4685 cm⁻¹) is not present in pure CO₂ but prominent in mixtures, it may be a good observational (spectral) indicator of whether solid CO₂ is a pure material or intimately mixed with other molecules. These observations may be applicable to Mars polar caps as well as outer Solar System bodies.  相似文献   

Estimating evapotranspiration for a temperate salt marsh,Newcastle, Australia     

C. E. Hughes  J. D. Kalma  P. Binning  G. R. Willgoose  M. Vertzonis 《水文研究》2001,15(6):957-975

Evapotranspiration was studied at a salt marsh site in the Hunter River estuary, NSW, Australia, during 1996–8. Estimates of actual evapotranspiration (E_a) were obtained for three sites using the eddy correlation method. These values were compared with results obtained with the Penman and Penman–Monteith equations, and with pan evaporation. The Penman–Monteith method was found to be most reliable in estimating daily and hourly evapotranspiration. Surface resistance values averaging 12 s m^?1 were derived from the eddy correlation estimates. Recent tidal flooding and rainfall were found to decrease surface resistance and increase E_a/E_p ratios. Estimates of evapotranspiration obtained using the Penman–Monteith method were shown to be sensitive to changes in surface resistance, canopy height and the method used to estimate net radiation from incoming solar radiation. These results underline the importance of accurately estimating such parameters based on site‐specific data rather than relying on empirical equations, which are derived primarily for crops and forests. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

The SCUBA 8-mJy survey – I. Submillimetre maps, sources and number counts     

S. E.Scott  M. J.Fox  J. S.Dunlop  S.Serjeant  J. A.Peacock  R. J.Ivison  S.Oliver  R. G.Mann  A.Lawrence  A.Efstathiou  M.Rowan-Robinson  D. H.Hughes  E. N.Archibald  A.Blain  M.Longair 《Monthly notices of the Royal Astronomical Society》2002,331(4):817-838

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Tracer dispersal by mid-ocean mesoscale eddies. Part I. Ensemble statistics     

Dale B. Haidvogel  Thomas Keffer 《Dynamics of Atmospheres and Oceans》1984,8(1):1-40

The rate at which, and the processes by which, a passive tracer is stirred and mixed in a turbulent mesoscale eddy field are examined for environmental parameters characteristic of a homogeneous mid-ocean region. The simulated, time-dependent eddy field is obtained by direct integration of the forced/damped barotropic vorticity equation; the dispersal of a spatially localized, instantaneous release of tracer (a “tracer spot”) within the evolving velocity field is subsequently computed from the advective-diffusive equation. An ensemble of 10 independent releases is used to determin the average spreading properties of the tracer spot.On an f-plane, the ensemble-averaged dispersal is approximately isotropic, and is associated with an effective diffusion rate substantially greater than that supported in the absence of turbulent advection. Quantitatively, the effective ensemble-averaged diffusivity is shown to be 0(UL), where U and L are characteristic velocity and length scales of the turbulent flow. This estimate is consistent with the traditional mixing length hypothesis. With the addition of β, the simulated flow field has substantial zonal anisotropy. Ensemble-averaged dispersal of tracer spots is similarly anisotropic, and the overall rate of tracer dispersal is substantially reduced over its f-plane value.Both with and without β, the initial rate at which maximum tracer concentration and total tracer variance decay are given by the approximate law exp[? αγt] where γ is the RMS rate of strain, and α is approximately constant at a value of 0.5. The heightened rate of variance loss over that associated with pure (subgridscale) diffusion is shown to be accommodated by the rapid transfer of tracer variance from the largest to the shortest scale tracer features, that is, by the rapid sharpening of tracer gradients by turbulent advection. A detailed examination of the dispersal of individual tracer realizations, and the associated question of tracer streakiness, is given in part II of this work (Keffer and Haidvogel, in preparation).  相似文献   

VLF waves in the magnetosphere     

A. R. W. Hughes 《Astrophysics and Space Science》1995,230(1-2):431-438

The study of VLF waves at ground based stations is an important source of information on particles trapped in the magnetosphere. By various techniques it is also possible to measure plasma densities, electric fields and monitor energetic particle injection. By studying the propagation of waves beneath the ionosphere it is possible to study particle precipitation from the magnetosphere. In this paper we summarise some of the techniques and results obtained from the study of VLF waves at the South African research station in Antarctica.  相似文献   

The Temperature and Salinity of the Surface Waters of the Irish Sea for the Period 1947-61     

P. Hughes 《Geophysical Journal International》1966,10(4):421-435

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A comprehensive model current system for high-latitude magnetic activity -II. The substorm component     

Gordon Rostoker  T. J. Hughes 《Geophysical Journal International》1979,58(3):571-581

Summary. In paper I of this series (Hughes & Rostoker) we have presented a composite model three-dimensional current system whose magnetic perturbation pattern is in good agreement with that observed at high latitudes during periods of moderate magnetospheric activity. In this paper we extend the model current system to demonstrate its ability to reproduce the magnetic perturbation pattern associated with the magnetospheric substorms. In agreement with previous workers, we find it necessary to include a region of intense equatorward current flow at the western edge of the westward travelling surge. For the particular substorm event presented in this paper, we find that the main eastward and westward electrojets intensified slightly before the appearance of the surge form, and we are able to evaluate quantitatively the amount of change involved.  相似文献