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61.
An improved Ewing heat probe frame 总被引:3,自引:0,他引:3
The standard Ewing heat probe frame has been improved through the design of a new takedown model whose parts are held together by lynch pins. When a 600 lb (272 kg) unit of this type is taken apart, the heaviest single piece of the dismantled unit weighs only 75 lb (34 kg).This makes it feasible for one person to handle, transport, and assemble the new unit. A central, main support member of a heat probe using this frame can be suspended over the side of a research vessel while the heavier temperature recorder and ballast weights are attached by means of the quickaction lynch pins. This makes it possible to use this device on relatively small vessels which are not designed for coring work, having a minimum of free deck space and without launching platforms or hydraulic A-frame booms. 相似文献
62.
Frank Rske 《Ocean Modelling》2006,11(3-4):235-297
A global dataset based on the ECMWF Re-Analyses (ERA) is presented that can be used as surface boundary conditions for ocean models with sea-ice components. The definition of these conditions is based on bulk formulae. To study the mean ocean circulation, a mean annual cycle on a daily basis was constructed from ERA for all relevant parameters including wind stress. Continental runoff is considered by using information about the catchment areas of the rivers and about the main drainage basins. The bulk formulae were extended by using sea ice concentration.To estimate meridional heat transports (MHT) and to avoid any drift in ocean model simulations, the heat and fresh water budgets have been closed by applying an inverse procedure to fine-tune the fluxes towards observed transports. To improve the MHTs on the Southern Hemisphere the winds and the short wave radiation at southern higher latitudes should be corrected. Furthermore, tests were performed concerning short wave radiation which was increased in the tropics and decreased in the subsidence zones.The heat and fresh water fluxes are assessed by using a scheme of Macdonald and Wunsch based on hydrographic sections. The net heat fluxes of ERA and of the forcing dataset are consistent with the heat flux divergences and convergences estimated by this scheme except for parts of the South Atlantic and the Indian Ocean sector of the Southern Ocean where none of these datasets is consistent with these estimates. In the subtropical South Indian Ocean the forcing dataset is consistent with these estimates while ERA are not. The flux components of ERA and the forcing dataset were compared to several observational datasets (SRB, SOC, HOAPS, GPCP, and CMAP). For each component, at least one of these datasets (especially HOAPS) supports the effects of the inverse procedure and the bulk formulae almost globally with some regional exceptions: short wave radiation in the tropical oceans and the subtropical North Atlantic, latent heat flux at higher latitudes, and precipitation in the northern North Atlantic.Comparisons to the NCAR/NCEP Re-Analyses (NRA) (versions 1 and 2) and the ECHAM model in place of ERA lead to similar results. In the North Atlantic the net heat fluxes of the model based datasets approach the hydrographic estimate with increasing resolution. Applied to any ocean/sea-ice model and compared to ERA, the forcing dataset would induce only a relative small net sea-surface buoyancy loss.A comparison of the forcing dataset to measurements made using one buoy deployed in the western Pacific warm pool and five buoys deployed in the subduction region of the Northeast Atlantic shows that at the site of the first buoy the net heat fluxes of the forcing dataset are in poorer agreement than those of ERA. At the sites of two subduction buoys both datasets show the same level of agreement within the error bars specified. At the sites of the three remaining subduction buoys the forcing dataset shows a marginal improvement on ERA. 相似文献
63.
Jesper Raakjær Dao Manh Son Karl-Johan Stæhr Holger Hovgård Nguyen Thi Dieu Thuy Kristine Ellegaard Frank Riget Dang Van Thi Phung Giang Hai 《Marine Policy》2007
Vietnam is in the process of introducing adaptive management based on indicators and time-series to manage its marine fisheries. The development of indicator-based frameworks for fisheries management has accelerated in recent years. This article describes the suite of indicators being suggested or used in Vietnam including the data-collection system. The Vietnamese approach is supported by an institutional structure consisting of a multi-disciplinary advisory system to facilitate the process of using indicators and to introduce knowledge-based management. The article concludes by identifying current problems and weaknesses and by providing suggestions for future improvement of the system. 相似文献
64.
65.
Jan E. Vermaat Rene N. Rollon Cristina Day A. Lacap Claire Billot Filipe Alberto Hildie M.E. Nacorda Frank Wiegman Jorge Terrados 《Journal of Sea Research》2004,52(4):201
Flower and fruit production of the abundant, tall, long-lived, dioecious, surface-pollinating seagrass species Enhalus acoroides (L.) Royle were estimated at seven sites in the reef flats off Bolinao (NW Luzon, The Philippines) featuring different fragmentation of the seagrass meadows. Fragmentation of the seagrass meadow was quantified as cover of E. acoroides and all seagrass species present in 20×20 m plots. E. acoroides and overall seagrass cover were correlated positively. The proportion of female flowers of E. acoroides that developed a fruit increased sharply as overall seagrass cover was around 50%. Apparent sex ratio bore no relationship with overall seagrass cover. This threshold-type of relationship suggests that fragmentation of seagrass meadows can have a major effect on the reproductive output of this species. A possible mechanism underlying these results would be a non-linear increase of the efficiency of trapping the surface-dispersed pollen with increasing seagrass canopy density. This provides the first evidence based on real data that fragmentation can affect the population dynamics of seagrass species. 相似文献
66.
Atίla Özgüç 《Solar physics》1989,123(2):381-383
After re-examination of data presented by Verma (1984), some misuse of solar parameteres published in Solar Geophysical Data is presented. Consequently some conclusions made by Verma (1984, 1986) on about the longitudinal distribution of cool solar surges based on these misuses are discussed. 相似文献
67.
Christoph Förste Roland Schmidt Richard Stubenvoll Frank Flechtner Ulrich Meyer Rolf König Hans Neumayer Richard Biancale Jean-Michel Lemoine Sean Bruinsma Sylvain Loyer Franz Barthelmes Saskia Esselborn 《Journal of Geodesy》2008,82(6):331-346
The recent improvements in the Gravity Recovery And Climate Experiment (GRACE) tracking data processing at GeoForschungsZentrum
Potsdam (GFZ) and Groupe de Recherche de Géodésie Spatiale (GRGS) Toulouse, the availability of newer surface gravity data
sets in the Arctic, Antarctica and North-America, and the availability of a new mean sea surface height model from altimetry
processing at GFZ gave rise to the generation of two new global gravity field models. The first, EIGEN-GL04S1, a satellite-only
model complete to degree and order 150 in terms of spherical harmonics, was derived by combination of the latest GFZ Potsdam
GRACE-only (EIGEN-GRACE04S) and GRGS Toulouse GRACE/LAGEOS (EIGEN-GL04S) mean field solutions. The second, EIGEN-GL04S1 was
combined with surface gravity data from altimetry over the oceans and gravimetry over the continents to derive a new high-resolution
global gravity field model called EIGEN-GL04C. This model is complete to degree and order 360 and thus resolves geoid and
gravity anomalies at half- wavelengths of 55 km at the equator. A degree-dependent combination method has been applied in
order to preserve the high accuracy from the GRACE satellite data in the lower frequency band of the geopotential and to form
a smooth transition to the high-frequency information coming from the surface data. Compared to pre-CHAMP global high-resolution
models, the accuracy was improved at a spatial resolution of 200 km (half-wavelength) by one order of magnitude to 3 cm in
terms of geoid heights. The accuracy of this model (i.e. the commission error) at its full spatial resolution is estimated
to be 15 cm. The model shows a reduced artificial meridional striping and an increased correlation of EIGEN-GL04C-derived
geostrophic meridional currents with World Ocean Atlas 2001 (WOA01) data. These improvements have led to select EIGEN-GL04C
for JASON-1 satellite altimeter data reprocessing.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
68.
Efficient GOCE satellite gravity field recovery based on least-squares using QR decomposition 总被引:3,自引:0,他引:3
We develop and apply an efficient strategy for Earth gravity field recovery from satellite gravity gradiometry data. Our approach
is based upon the Paige-Saunders iterative least-squares method using QR decomposition (LSQR). We modify the original algorithm
for space-geodetic applications: firstly, we investigate how convergence can be accelerated by means of both subspace and
block-diagonal preconditioning. The efficiency of the latter dominates if the design matrix exhibits block-dominant structure.
Secondly, we address Tikhonov-Phillips regularization in general. Thirdly, we demonstrate an effective implementation of the
algorithm in a high-performance computing environment. In this context, an important issue is to avoid the twofold computation
of the design matrix in each iteration. The computational platform is a 64-processor shared-memory supercomputer. The runtime
results prove the successful parallelization of the LSQR solver. The numerical examples are chosen in view of the forthcoming
satellite mission GOCE (Gravity field and steady-state Ocean Circulation Explorer). The closed-loop scenario covers 1 month
of simulated data with 5 s sampling. We focus exclusively on the analysis of radial components of satellite accelerations
and gravity gradients. Our extensions to the basic algorithm enable the method to be competitive with well-established inversion
strategies in satellite geodesy, such as conjugate gradient methods or the brute-force approach. In its current development
stage, the LSQR method appears ready to deal with real-data applications. 相似文献
69.
This paper introduces a new method for GPS signal acquisition, which is based on the repeatability of successive code phase
measurements and the M-of-N search algorithm. The performance of the proposed method in terms of probability of signal detection
is similar to that of traditional methods, except that the calculation of the probability of detection does not rely on the
noise distribution or the Carrier-to-Noise ratio (C/N0). The code phase repeatability-based method is presented along with equations for probability of detection and probability
of false detection. If the distribution of the noise is known, it also provides an estimate of the C/N0. The proposed method is illustrated for coherent and non-coherent acquisition and C/N0 estimation. 相似文献
70.
Mirdita Zone ophiolites and associated sediments in Albania reveal Neotethys Ocean origin 总被引:1,自引:1,他引:0
Hans-Jürgen Gawlick Wolfgang Frisch Lirim Hoxha Paulian Dumitrica Leopold Krystyn Richard Lein Sigrid Missoni Felix Schlagintweit 《International Journal of Earth Sciences》2008,97(4):865-881
The Mirdita Ophiolite Zone in Albania is associated with widespread mélanges containing components of up to nappe-size. We
dated matrix and components of the mélange by radiolarians, conodonts, and other taxa. The components consist of radiolarites,
pelagic limestones and shallow-water limestones, all of Triassic age, as well as ophiolites. Triassic radiolarite as a primary
cover of ophiolite material proves Middle Triassic onset of Mirdita ocean-floor formation. The mélange contains a turbiditic
radiolarite-rich matrix (“radiolaritic flysch”), dated as Late Bajocian to Early Oxfordian. It formed as a synorogenic sediment
during west-directed thrusting of ophiolite and sediment-cover nappes representing ocean floor and underplated fragments of
the western continental margin. The tectonic structures formed during these orogenic events (“Younger Kimmeridian or Eohellenic
Orogeny”) are sealed by Late Jurassic platform carbonates. The geological history conforms with that of the Inner Dinarides
and adjoining areas; we therefore correlate the Mirdita-Pindos Ophiolite Zone with the Vardar Zone and explain its present
position by far-distance west-directed thrusting. 相似文献