Heat flow and age of the Gulf of Oman     

I. Hutchison  K.E. Louden  R.S. White  R.P. von Herzen 《Earth and Planetary Science Letters》1981

We present the results of twenty heat flow stations in the Gulf of Oman which are used to infer the first reliable age estimates for the basin. A mean surface heat flux of 42.6±3.6 mW m^?2 exhibits no significant regional variation. After correction for thick and rapidly deposited sediments this yields an age of 70 to 100 Ma according to oceanic thermal models. This age is also consistent with the sediment corrected basement depths of 5.5–6.0 km and with formation during the Cretaceous quiet zone. The latter can explain the absence of magnetic sea-floor spreading lineations. Heat flow measurements are also used to confirm the presence of gas hyrdate layers. The measured thermal gradient yields a depth for the solid to free gas phase transition which is the same as that deduced from “bright spots” seen on seismic reflection profiles.  相似文献   

Measurement of the Primary Production of Phytoplankton in the Aquatic Environment During the Solar Eclipse     

B. B. Jana  U. K. De 《洁净——土壤、空气、水》1981,9(5):599-602

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Competition for the general cargo transports of Sweden's foreign trade     

Christopher von Schirach-Szmigiel 《GeoJournal》1981,2(2):133-146

The object of the paper is to analyze changes in modal and port allocation of general cargo flows in Sweden's foreign trade between 1960 and 1976. It summarizes some results of a forthcoming report on the project Tendencies in Liner Shipping financed by the Transport Research Delegation, Stockholm.  相似文献   

Detecting rift basins in the Evans Ice Stream region of West Antarctica using airborne gravity data     

Philip C. Jones  Ashley C. Johnson  Ralph R. B. von Frese  Hugh Corr 《Tectonophysics》2002,347(1-3)

A total of 11,500 line km of aerogravity data have been used to construct an free-air gravity anomaly map for the Antarctic region that may contain the microplate boundary between the Haag Nunataks block and southern Antarctic Peninsula. Along-line free-air gravity anomaly data resolved wavelengths of 9 km or greater with better than 5 mGal accuracy. Coincident radio echo soundings provided data to construct a digital terrain model. The gravity effect of the terrain was calculated by Gauss–Legendre quadrature (GLQ) and spectrally correlated with the free-air gravity data. Terrain-correlated free-air anomalies related to possible isostatic imbalances of the crust were separated from terrain-decorrelated anomalies that may reflect intra-crustal density contrasts. Subtracting terrain-correlated free-air anomalies from the gravity effects of the terrain yielded compensated terrain gravity effects (CTGE) that were used to model the Moho by inversion. The results indicate moderate but significant crustal thinning below the Evans Ice Stream that is consistent with an extensional origin for the deep, wide, steep-sided trough that contains the ice stream as well as the continued elevation of the footwall flank of the basin. Changes along the axis of the rift, both in the gravity anomaly field and the distribution of Moho topography, can be explained by processes associated with continental lithospheric extension. Subsequently, many of the features produced by extension have been modified by glacial erosion and the sub-ice topography and gravity data reflect this.  相似文献   

Atmospheric input of nitrogen into the North Sea: ANICE project overview     

Gerrit de Leeuw  Leo Cohen  Lise Marie Frohn  Gary Geernaert  Ole Hertel  Bjarne Jensen  Tim Jickells  Laura Klein  Gerard J. Kunz  Soren Lund  Marcel Moerman  Frank Müller  Britta Pedersen  Knut von Salzen  K. Heinke Schlünzen  Michael Schulz  Carsten A. Skjth  Lise-Lotte Sorensen  Lucinda Spokes  Susanne Tamm  Elisabetta Vignati 《Continental Shelf Research》2001,21(18-19)

The aim of the atmospheric nitrogen inputs into the coastal ecosystem (ANICE) project is to improve transport–chemistry models that estimate nitrogen deposition to the sea. To achieve this, experimental and modelling work is being conducted which aims to improve understanding of the processes involved in the chemical transformation, transport and deposition of atmospheric nitrogen compounds. Of particular emphasis within ANICE is the influence of coastal zone processes. Both short episodes with high deposition and chronic nitrogen inputs are considered in the project. The improved transport–chemistry models will be used to assess the atmospheric inputs of nitrogen compounds into the European regional seas (the North Sea is studied as a prototype) and evaluate the impact of various emission reduction strategies on the atmospheric nitrogen loads. Assessment of the impact of atmospheric nitrogen on coastal ecosystems will be based on comparisons of phytoplankton nitrogen requirements, other external nitrogen inputs to the ANICE area of interest and the direct nitrogen fluxes provided by ANICE. Selected results from both the experimental and modelling components are presented here. The experimental results show the large spatial and temporal variability in the concentrations of gaseous nitrogen compounds, and their influences on fluxes. Model calculations show the strong variation of both concentrations and gradients of nitric acid at fetches of up to 25 km. Aerosol concentrations also show high temporal variability and experimental evidence for the reaction between nitric acid and sea salt aerosol is provided by size-segregated aerosol composition measured at both sides of the North Sea. In several occasions throughout the experimental period, air mass back trajectory analysis showed connected flow between the two sampling sites (the Weybourne Atmospheric Observatory on the North Norfolk coast of the UK and Meetpost Noordwijk, a research tower at 9 km off the Dutch coast). Results from the METRAS/SEMA mesoscale chemistry transport model system for one of these cases are presented. Measurements of aerosol and rain chemical composition, using equipment mounted on a commercial ferry, show variations in composition across the North Sea. These measurements have been compared to results obtained with the transport–chemistry model ACDEP which calculates the atmospheric inputs into the whole North Sea area. Finally, the results will be made available for the assessment of the impact of atmospheric nitrogen on coastal ecosystems.  相似文献   

Tracer experiment with sulfur hexafluoride to quantify the vertical transport in a meromictic pit lake     

Christoph von Rohden  Johann Ilmberger 《Aquatic Sciences - Research Across Boundaries》2001,63(4):417-431

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Groundwater study in the Piedmont zone of Mechi Mahananda interfluve in Darjiling district,West Bengal using remote sensing techniques     

M. M. Jana  M. Dutta 《Journal of the Indian Society of Remote Sensing》1996,24(1):43-52

The Mechi-Mahananda interfluve is a transitional area between the hills and the plains and exhibits a wide range of topographical variations. The drainage system of the area has a close relationship with lithology and landforms. The rivers originating in the hills attain a braiding character and have well developed alluvial fans. Piedmont plain covers a large area and has high ground water potential. The river terraces and flood plains also have high potentialities of ground water targeting. Fluctuation of water table is very high in the upper piedmont plain dependent upon the proximity to the drainage lines.  相似文献   

High resolution simulation of a flow past the Pyrenees     

K. von der Emde  Ph. Bougeault 《Meteorology and Atmospheric Physics》1997,62(1-2):1-8

Summary A hydrostatic model is applied to a case study from the Pyrenean field experiment PYREX. The results from this simulation are compared with measurements, with the aim to evaluate the model behaviour in the case of a flow past a steep orography. The initial and boundary data, which were used for the simulation, were produced with the T213 reassimilation system at Reading by the European Center for Medium-Range Weather Forecasts (ECMWF). The comparison of the results with observations show that the local wind systems are captured reasonably well by the model. In particular the evolution of two counter rotating eddies in the lee of the Pyrenean mountain range are simulated correctly in space and time. Also the calculated orographic drag and vertical wave momentum flux agreed well with the measurements.With 15 Figures  相似文献   

European Observation Network: Ground - Based Support for Gamma-Ray Satellites     

René Hudec  Pavel Spurný  Jan Florián  Jaroslav Boček  Miloš Tichý  Jana Tichá  Libor Vyskočil  Wolfgang Wenzel  Scott Barthelmy  Thomas Cline  Niels Gehrels  Gerald Fishman  Chryssa Kouveliotou  Charles Meegan  Asen Mutafov 《Experimental Astronomy》1997,7(4):319-323

We present first preliminary results obtained with the European Observation Network consisting of 9 observatories in the Czech Republic, Germany and Bulgaria. We also discuss related problems such as the background of unknown variable stars and suggest a strategy for work in this area.  相似文献   

A theoretical model of altitudinal distribution of sodium atom     

P. K. Jana  S. K. Midya 《Earth, Moon, and Planets》1995,71(1-2):147-152

It has been well accepted that sodium is a minor constituent in the upper atmosphere. The possible formation and destruction processes of sodium has been considered and the following results are obtained:(i) An empirical equation has been established for calculation of the concentration of sodium for different altitude and time.(ii) It is confirmed that the rate constant for the reaction NaO + O₂ Na + O₃ is temperature dependent. The activation energy for this reaction is 70.88 Kcals/mole.  相似文献