排序方式： 共有7条查询结果，搜索用时 15 毫秒
1
1.
An experimental method to investigate submarine bedform signatures at the sea surface is described. The study area was the Lister Tief in the German Bight of the southeastern North Sea, a semienclosed tidal basin with asymmetric and very large sand waves. In-situ and remote measurements of surface roughness were obtained simultaneously. An X-band wave monitoring radar, an oceanographic multisensor sea surface buoy, an acoustic Doppler current profiler, and a standard echo sounder were operated on and from board a research vessel while drifting along the tidal channel 相似文献
2.
A map depicting predicted classes of soil magnetic susceptibility in Angola was produced. The map is based on a classification
system for the susceptibility of tropical soils set up by the authors and a 1:2,000,000 scale FAO soil map. Statistical data
of two large groups of parent rock—ultrabasic, basic and intermediate igneous rocks on the one hand and acid igneous rocks
and some slightly metamorphosed rocks and clastic sediments on the other—had been linked to three associated degrees of weathering.
These determining factors were used to classify Angolan soils, and the overall method is semi-quantitative. The resulting
map shows that easily available pedological information as given by FAO soil maps is generally appropriate to predict soil
magnetic susceptibility. Potential metal detector performance failures may be predicted. The resulting information is a useful
tool for planning the use of appropriate techniques in landmine clearance operations. 相似文献
3.
4.
Summary Quantitative sunglitter radiance modulations at the ocean surface due to internal waves were calculated applying a simple
first order theory. The results have been compared with the image data of internal wave signatures northeast of Nantucket
Shoals off the coast of Massachusetts, U.S.A., taken by the Earth Terrain Camera (ETC) during the Skylab mission. The maximum
magnitudes of sunglitter radiance modulations predicted by the theory are comparable to the satellite image data. The extreme
values of calculated modulations depend only weakly on the wavelength of the internal wave signature. This is consistent with
the analysed ETC data. On the other hand, the shapes of simulated and measured image intensity transects across an internal
wave packet are different. This may possibly be explained by the assumed idealized sinusoidal type of thermocline used in
the calculations. The theory predicts that sunglint signatures of internal waves are advected relative to positions of extreme
slope regions of the thermocline due to currents.
Strahldichtemodulation des Sonnenglitzerns durch interne Wellen
Zusammenfassung Quantitative Strahldichtemodulationen des Sonnenglitzerns an der Meeresoberfl?che durch interne Wellen werden unter Verwendung einer einfachen ersten Ordnungstheorie berechnet. Die Ergebnisse werden mit Bilddaten von internen Wellensignaturen nord?stlich von Nantucket Shoals vor der Küste von Massachusetts, U.S.A., verglichen, die w?hrend der Skylab-Mission von der Erdbeobachtungskamera (ETC) aufgenommen wurden. Die Werte der maximalen Strahldichtemodulation des Sonnenglitzerns, die von der Theorie vorhergesagt werden, sind mit den Satellitenbilddaten vergleichbar. Die Extremwerte der berechneten Modulationen h?ngen nur schwach von der Wellenl?nge der internen Wellensignaturen ab. Dieses stimmt mit den analysierten ETC Daten überein. Auf der anderen Seite sind die Kurvenverl?ufe zwischen den simulierten und gemessenen Bildintensit?tsprofilen entlang eines internen Wellenpaketes unterschiedlich. Dieses kann m?glicherweise durch den angenommenen idealisierten sinusf?rmigen Typ der Thermokline erkl?rt werden, der für die Berechnungen verwendet wurde. Die Theorie macht die Vorhersage, da? Signaturen des Sonnenglitzerns von internen Wellen durch Str?mungen advektiert werden relativ zu den Positionen der extremen Neigungsregionen der Thermokline.相似文献
5.
6.
Dissolved organic matter dynamics during the spring snowmelt at a boreal river valley mire complex in Northwest Russia 
下载免费PDF全文
下载免费PDF全文 Armine Avagyan Benjamin R. K. Runkle Nina Hennings Hannes Haupt Tarmo Virtanen Lars Kutzbach 《水文研究》2016,30(11):1727-1741
Boreal mire landscapes are rich in soil carbon and significantly contribute to the carbon input of aquatic ecosystems. They are composed of different mesoscale ecohydrological subunits, whose individual contributions to the water and carbon export of mire catchments are not well understood. The spring snowmelt period is the major hydrological event in the annual water cycle of the boreal regions and strongly influences the carbon flux between the terrestrial and aquatic systems. The aim of this study was (1) to provide a conceptual understanding of the spatial and temporal dynamics of the surface water chemistry along a swamp forest‐fen‐bog gradient during the snowmelt period, (2) to quantify the exported dissolved organic carbon (DOC) content in the runoff and (3) to identify the ecohydrological landscape unit that contributes most to DOC export during the snowmelt period in a heterogeneous mire complex in Northwest Russia. The highest DOC concentrations were detected in the swamp forest, and the lowest concentrations were observed at the treeless bog by the end of the snowmelt period (swamp forest: 37–43 mg l?1, bog: 13–17 mg l?1). During the spring snowmelt period, a significant amount (~1.7 g C m?2) of DOC was transferred by the ~74 mm of runoff from the catchment into the river. Variability in the thawing periods led to differences in the relative contributions of each ecohydrological zone to the carbon export measured at a stream channel draining the studied part of the mire complex. An increased understanding of the variation in DOC concentrations and contributions from the mesoscale ecohydrological subunits to carbon export can help to predict the potential regional loss of DOC based on land cover type under climate change. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
7.
1