Neuere Veröffentlichungen     

F. Nusser  H. Gabler  Otto Pratje  P. Christoph 《Ocean Dynamics》1951,4(1-2):74-77

Ohne Zusammenfassung  相似文献   

I/I ratios in Scottish coastal surface sea water: Geographical and temporal responses to changing emissions     

Christoph Schnabel  Valérie Olive  Mariko Atarashi-Andoh  Andrew Dougans  Robert M. Ellam  Stewart Freeman  Colin Maden  Martin Stocker  Hans-Arno Synal  Lukas Wacker  Sheng Xu 《Applied Geochemistry》2007

This work constitutes the first survey of I isotope ratios for Scottish sea water including the first data for the west of Scotland. These data are of importance because of the proximity to the world’s second largest emission source of ¹²⁹I to the sea, the Sellafield nuclear reprocessing plant, because of the increasing importance of the sea to land transfer of ¹²⁹I and also as input data for dose estimates based on this pathway of ¹²⁹I. ¹²⁹I/¹²⁷I ratios in SW Scotland reached 3 × 10⁻⁶ in 2004. No strong variation of I isotope ratios was found from 2003 to 2005 in Scottish sea waters. Iodine isotope ratios increased by about a factor of 6 from 1992 to 2003 in NE Scotland, in agreement with the increase of liquid ¹²⁹I emissions from Sellafield over that time period. It is demonstrated that ¹²⁹I/¹²⁷I ratios agree better than ¹²⁹I concentrations for samples from similar locations taken in very close temporal proximity, indicating that this ratio is more appropriate to interpret than the radionuclide concentration.  相似文献   

The system H₂O-NaCl. Part I: Correlation formulae for phase relations in temperature-pressure-composition space from 0 to 1000 °C, 0 to 5000 bar, and 0 to 1 X_NaCl     

Thomas Driesner  Christoph A. Heinrich 《Geochimica et cosmochimica acta》2007,71(20):4880-4901

Realistic simulations of fluid flow in geologic systems have severely been hampered by the lack of a consistent formulation for fluid properties for binary salt-water fluids over the temperature-pressure-composition ranges encountered in the Earth’s crust. As the first of two companion studies, a set of correlations describing the phase stability relations in the system H₂O-NaCl is developed. Pure water is described by the IAPS-84 equation of state. New correlations comprise the vapor pressure of halite and molten NaCl, the NaCl melting curve, the composition of halite-saturated liquid and vapor, the pressure of vapor + liquid + halite coexistence, the temperature-pressure and temperature-composition relations for the critical curve, and the compositions of liquid and vapor on the vapor + liquid coexistence surface. The correlations yield accurate values for temperatures from 0 to 1000 °C, pressures from 0 to 5000 bar, and compositions from 0 to 1 X_NaCl (mole fraction of NaCl). To facilitate their use in fluid flow simulations, the correlations are entirely formulated as functions of temperature, pressure and composition.  相似文献   

Retrieval of mixing height and dust concentration with lidar ceilometer   总被引：4，自引：2，他引：4  

Christoph Münkel  Noora Eresmaa  Janne Räsänen  Ari Karppinen 《Boundary-Layer Meteorology》2007,124(1):117-128

The Vaisala ceilometers CT25K and CL31 are eye-safe single lens lidar systems reporting attenuated backscatter profiles; they often operate 24 h a day in fully automated, hands-off operation mode. These profiles can be used for more than just cloud-base height determination. In dry weather situations, there is a fairly good correlation between the ceilometer near-range backscatter and in situ PM10 concentration readings. The comparison of mixing height values based on soundings and on ceilometer backscattering profiles indicates that ceilometers are suitable instruments for determining the convective mixing height. Its enhanced optics and electronics enables the CL31 ceilometer to detect fine boundary-layer structures whose counterparts are seen in temperature profiles.  相似文献   

Analysis of Low-Frequency Turbulence Above Tall Vegetation Using a Doppler Sodar     

Christoph Thomas  Jens-Christopher Mayer  Franz X. Meixner  Thomas Foken 《Boundary-Layer Meteorology》2006,119(3):563-587

This study applies acoustic sounding to observe coherent structures in the roughness sublayer (RSL) above tall vegetated surfaces. Data were collected on 22 days during two separate field experiments in summer 2003. A quality control scheme was developed to ensure high data quality of the collected time series. The data analysis was done using both discrete and continuous wavelet transform. The flow in the RSL was found to be a superposition of dynamic Kelvin–Helmholtz instabilities and convective mixing. The characteristic time scales for coherent structures resulting from the dynamic instabilities were observed to be approximately 20–30 s while thermal eddies have much larger time scales of 190–210 s. The degree of vertical coherency in the RSL increases with the flow evolving from neutral to near-convective conditions. This increase in the degree of organisation is attributed to the evolution of attached thermal eddies. The coherent structures resulting from instabilities were found to be present throughout the RSL but do not contribute to the increased vertical coherency. An alternative conceptual approach for the definition of the RSL is proposed, which yields its maximum vertical extent to five times the canopy height.  相似文献   

A Case Study on the Effects of Heterogeneous Soil Moisture on Mesoscale Boundary-Layer Structure in the Southern Great Plains, U.S.A. Part I: Simple Prognostic Model     

Ankur R. Desai  Kenneth J. Davis  Christoph J. Senff  Syed Ismail  Edward V. Browell  David R. Stauffer  Brian P. Reen 《Boundary-Layer Meteorology》2006,119(2):195-238

The atmospheric boundary-layer (ABL) depth was observed by airborne lidar and balloon soundings during the Southern Great Plains 1997 field study (SGP97). This paper is Part I of a two-part case study examining the relationship of surface heterogeneity to observed ABL structure. Part I focuses on observations. During two days (12–13 July 1997) following rain, midday convective ABL depth varied by as much as 1.5 km across 400 km, even with moderate winds. Variability in ABL depth was driven primarily by the spatial variation in surface buoyancy flux as measured from short towers and aircraft within the SGP97 domain. Strong correlation was found between time-integrated buoyancy flux and airborne remotely sensed surface soil moisture for the two case-study days, but only a weak correlation was found between surface energy fluxes and vegetation greenness as measured by satellite. A simple prognostic one-dimensional ABL model was applied to test to what extent the soil moisture spatial heterogeneity explained the variation in north–south ABL depth across the SGP97 domain. The model was able to better predict mean ABL depth and variations on horizontal scales of approximately 100 km using observed soil moisture instead of constant soil moisture. Subsidence, advection, convergence/divergence and spatial variability of temperature inversion strength also contributed to ABL depth variations. In Part II, assimilation of high-resolution soil moisture into a three-dimensional mesoscale model (MM5) is discussed and shown to improve predictions of ABL structure. These results have implications for ABL models and the influence of soil moisture on mesoscale meteorology  相似文献   

Freshwater pulses in the eastern Arctic Ocean during Saalian and Early Weichselian ice-sheet collapse     

Jochen Knies  Christoph Vogt 《Quaternary Research》2003,60(3):243-251

Improved multiparameter records from the northern Barents Sea margin show two prominent freshwater pulses into the Arctic Ocean during MIS 5 that significantly disturbed the regional oceanic regime and probably affected global climate. Both pulses are associated with major iceberg-rafted debris (IRD) events, revealing intensive iceberg/sea ice melting. The older meltwater pulse occurred near the MIS 5/6 boundary (∼131,000 yr ago); its ∼2000 year duration and high IRD input accompanied by high illite content suggest a collapse of large-scale Saalian Glaciation in the Arctic Ocean. Movement of this meltwater with the Transpolar Drift current into the Fram Strait probably promoted freshening of Nordic Seas surface water, which may have increased sea-ice formation and significantly reduced deep-water formation. A second pulse of freshwater occurred within MIS 5a (∼77,000 yr ago); its high smectite content and relatively short duration is possibly consistent with sudden discharge of Early Weichselian ice-dammed lakes in northern Siberia as suggested by terrestrial glacial geologic data. The influence of this MIS 5a meltwater pulse has been observed at a number of sites along the Transpolar Drift, through Fram Strait, and into the Nordic Seas; it may well have been a trigger for the North Atlantic cooling event C20.  相似文献   

Book Review     

Christoph  Clauser 《Geophysical Journal International》2003,153(2):508-509

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Wei-Chyung Wang, Ivar S. A. Isaksen (eds): Atmospheric Ozone as a Climate Gas, General Circulation Model Simulations     

Christoph Brühl 《Journal of Atmospheric Chemistry》1998,30(2):313-314

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Dissipation and mixing in a coastal jet: A Baltic Sea case study     

Christoph Zülicke  Eberhard Hagen  Adolf Stips 《Aquatic Sciences - Research Across Boundaries》1998,60(3):220-235

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