Acceptance Speech for the V. M. Goldschmidt Medal     

Konrad B. Krauskopf 《Geochimica et cosmochimica acta》1983,47(5):982-983

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Martian Seasonal CO₂ Ice in Polygonal Troughs in Southern Polar Region: Role of the Distribution of Subsurface H₂O Ice     

Konrad J. KossackiWojciech J. Markiewicz 《Icarus》2002,160(1):73-85

The Mars Orbiter Camera onboard the Mars Global Surveyor has obtained several images of polygonal features in the southern polar region. In images taken during the end of the southern spring, when the surrounding surface is free of the seasonal frost, CO₂ ice still appears to be present within the polygonal troughs. In Earth's polar regions, polygons such as these are indicative of water ice in the ground below. We analyzed the seasonal evolution of the thermal state and the CO₂ content of these features. Our 2-D model includes condensation and sublimation of the CO₂ ice, a self consistent treatment of the variations of the thermal properties of the regolith, and the seasonal variations of the local atmospheric pressure which we take from the results of a general circulation model. We find that the residence time of seasonal CO₂ ice in troughs depends not only on atmospheric opacity and albedo of the CO₂ ice, but also and most significantly on the distribution of water ice in the regolith. Optical properties of the atmosphere and surface CO₂ ice can be independently obtained from observations. To date this is not true about the distribution of water ice below the surface. Our analysis quantifies the dependence of the seasonal cycle of the CO₂ ice within the troughs on the assumed distribution of the water ice below the surface. We show that presence of water ice in the ground at a depth smaller than the depth of the troughs reduces winter condensation rate of CO₂ ice. This is due to higher heat flux conducted from the water ice rich regolith toward the facets of the troughs.  相似文献   

Intramonthly Indices of the Pacific/North American Teleconnection Pattern and Temperature Regimes over the United States     

C. E. Konrad 《Theoretical and Applied Climatology》1998,60(1-4):11-19

Summary Previous work has examined relationships between the planetary scale Pacific North American (PNA) teleconnection pattern and regional scale mean temperature over portions of the United States, but analyses have been restricted to monthly values of these two variables. It is not clear if this is the most appropriate scale for relating PNA patterns to temperature. In this study, PNA indices are related to various aspects of temperature over a range of time scales spanning one month. To carry this out, standardized PNA indices are calculated for 6 time intervals ranging from 5 to 30 days over a period of 27 winter seasons. Standardized regional scale temperature anomalies are assessed over various regions of the United States and used to compute mean, maximum, and minimum temperature anomalies over the same 6 time intervals. Correlation matrices are then constructed to provide relationship characteristics between the PNA indices and temperature measures within the intramonthly time scale. Only the southeastern and northwestern regions of the United States display significant relationships between the PNA indices and temperature. Over the Southeast, temperature anomalies on short time scales relate most strongly to PNA indices computed over time intervals of 25 to 30 days; this is especially the case for the minimum temperature anomaly. The strongest relationships, however, are observed between the PNA index and temperature anomalies computed on a 20–25 day time interval. Over the Northwest, the relationships are not as strong and somewhat more varied. Most notably, moderate connections are found between the 30 day PNA index and minimum temperature anomalies computed over a 25 day period. Received August 18, 1997Revised November 28, 1997  相似文献   

A Servohydraulically-controlled Deformation Apparatus for Rock Deformation under Conditions of Ultra-high Pressure Metamorphism   总被引：5，自引：0，他引：5  

E. Rybacki  J. Renner  K. Konrad  W. Harbott  F. Rummel  B. Stöckhert 《Pure and Applied Geophysics》1998,152(3):579-606

—A deformation apparatus has been developed to study the mechanical behaviour of high pressure and ultra-high pressure metamorphic rocks. It is based on the conventional Griggs design and the molten salt cell concept introduced by H. E. Green II. Both, the axial loading and the confining pressure are servohydraulically controlled. Alternatively, a self-made multilayer pressure vessel or a commercial stripwound construction are used. The pressure cell is improved with respect to systems described previously by the use of different salt mixtures with low eutectic temperatures, by a mechanically stable arrangement of the thermocouples, and by an optimization of the frictional characteristics of the axial loading system. The apparatus has been successfully used in deformation experiments on cylindrical aragonite and coesite samples 3 to 4 mm in diameter and 6 to 10 mm in length at confining pressures up to 3.7 GPa and temperatures up to 1170°C.  相似文献   

Measuring galaxy potentials using shell kinematics     

Michael R. Merrifield  & Konrad Kuijken 《Monthly notices of the Royal Astronomical Society》1998,297(4):1292-1296

We show that the kinematics of the shells seen around some elliptical galaxies provide a new, independent means for measuring the gravitational potentials of elliptical galaxies out to large radii. A numerical simulation of a set of shells formed in the merger between an elliptical and a smaller galaxy reveals that the shells have a characteristic observable kinematic structure, with the maximum line-of-sight velocity increasing linearly as one moves inward from a shell edge. A simple analytic calculation shows that this structure provides a direct measure of the gradient of the gravitational potential at the shell radius. In order to extract this information from attainable data, we have also derived a complete distribution of line-of-sight velocities for material within a shell; comparing the observed spectra of a shell to a stellar template convolved with this distribution will enable us to measure the gradient of the potential at this radius. Repeating the analysis for a whole series of nested shells in a galaxy allows the complete form of the gravitational potential as a function of radius to be mapped out. The requisite observations lie within reach of the up-coming generation of large telescopes.  相似文献   

International agreement to stabilize climate: Lessons from the Montreal protocol     

Konrad Von Moltke 《Climatic change》1989,14(3):211-212

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Natural analogues for the transuranic actinide elements: An investigation in Minas Gerais,Brazil     

Merril Eisenbud  Konrad Krauskopf  Eduardo Penna Franca  Wayne Lei  Robert Ballad  Paul Linsalata  Kenkichi Fujimori 《Environmental Geology》1984,6(1):1-9

A highly weathered deposit of thorium and rare earth elements located near the summit of a hill in the state of Minas Gerais, Brazil, is being studied as an analogue for a radioactive waste repository that sometime in the distant future may be eroded to the surface or intruded by groundwater Thorium serves as an analogue for Pu⁴⁺, and La³⁺ as an analogue for Cm³⁺ and Am³⁺ The mobilization rate constants of the analogue elements by groundwater are so slow (of the order of 10⁻⁹ per year) as to suggest that essentially complete radioactive decay of the transuranic actinides would occur in place even under the relatively unfavorable conditions that exist at a site such as this  相似文献   

Climate-change impacts on sagebrush habitat and West Nile virus transmission risk and conservation implications for greater sage-grouse     

Anne Schrag  Sarah Konrad  Scott Miller  Brett Walker  Steve Forrest 《GeoJournal》2011,76(5):561-575

Greater sage-grouse (Centrocercus urophasianus) are threatened by loss of sagebrush habitat and the spread of West Nile virus throughout much of their range in North America; yet, future impacts of climate change on these potential stressors have not been addressed. Here, we aim to quantify the potential impacts of climate change on the distribution of climatically suitable habitat for sagebrush and on transmission risk for West Nile virus in the eastern portion of the species’ range. We used Maxent to model the current and future climatically suitable habitat for two dominant sagebrush species in the study area, and we used a degree-day model to predict future West Nile virus transmission risk under likely climate-change scenarios. Our models suggest that areas with the highest future suitability for sagebrush habitat will be found in southwestern Wyoming and north-central Montana. The degree-day model suggests that greater sage-grouse in western portions of the study area, which are generally higher in elevation than where West Nile virus currently occurs, will see increasing risk of transmission in the future. We developed a spatially explicit map of suggested management actions based on our predictions that will aid in conservation of the species into the coming decades.  相似文献   

International Congress and Trade fair on Geosciences and Technology k?ln (cologne), Germany, September 18–21, 1991     

Konrad Murr K?ln 《GeoJournal》1990,22(4):453

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Evolution of depressions on Comet 67P/Churyumov-Gerasimenko: Role of ice metamorphism     

Konrad J. Kossacki  Jacek Leliwa-Kopystyński  Slawomira Szutowicz 《Icarus》2006,184(1):221-238

This work is intended to investigate the influence of temperature-dependent metamorphism of ice on the shape of small depressions in the surface of cometary nuclei. We are mainly interested in the role of initial cohesivity of a nucleus. For this purpose we simulate sublimation of ice from the facets of initially cylindrical depressions in ice of different initial structure. The simulations account for the diurnal and orbital changes of insolation and its dependence on the current shape of the depressions. Our model includes heat transport in the cometary material and metamorphism of ice. We present the results obtained for the nucleus of the Comet 67P/Churyumov-Gerasimenko, target of the ESA cornerstone mission Rosetta.  相似文献