Acontribute to the informal theory of geological mineral samples     

Erwin L. Zodrow 《Mathematical Geology》1974,6(2):203

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Semidiurnal and Long-Period Components in Polar Motion Connected with the Triaxiality of Ellipsoids of Inertia of the Earth and Planets     

Molodensky  S.M.  Groten  E. 《Studia Geophysica et Geodaetica》2001,45(1):37-54

The influence of the Earth's inertia ellipsoid triaxiality, both on the motion of the Angular Velocity Vector with respect to Tisserand's reference frame (hereinafter – AVV,T), the motion of the same vector in Space (hereinafter – AVV,S) as well as on the motion of Tisserand's Reference Frame in Space (hereinafter – TRF,S) is considered. It is shown that the observable effects are as follows: (1) in all three types of motions (AVV,T), (AVV,S) and (TRF,S) there are significant (observable) semidiurnal components which may be detected by modern GPS- and VLBI-measurements. Additionally, there is a long-periodic perturbation of (TRF,S) motion which is rather small for the Earth, but may be significant for the other planets of the Solar System (if the triaxiality of the inertia ellipsoid is sufficiently large and whenever the orbital and diurnal rotations are synchronous and, at the points of equinoxes, the orientation of the planet's principal equatorial moments of inertia is invariable in space). For the case of the Earth, the results of our calculations are compared with the results of modern GPS-observations.  相似文献   

Advanced Physical Geodesy and Gravimetry by M. Pick,Ministry of Defence of the Czech Republic,Prague 2000, 276 pages,ISBN: 80-7278-020-4     

Groten  E. 《Studia Geophysica et Geodaetica》2001,45(1):103-104

Studia Geophysica et Geodaetica -  相似文献   

Morphology and curvature of delta slopes in Swiss lakes: lessons for the interpretation of clinoforms in seismic data   总被引：1，自引：0，他引：1  

Erwin W. Adams  Wolfgang Schlager  & Flavio S. Anselmetti 《Sedimentology》2001,48(3):661-679

Seismic surveys were conducted and bathymetric data obtained from four alpine lakes in Switzerland. The curvature of the delta slopes was analysed with mathematical equations. Linear or exponential profiles are observed, representing planar or concave morphologies respectively. Planar profiles are interpreted to represent sediment that rests at the angle-of-repose. The slope angle of these profiles shows a correlation with sediment calibre. Exponential profiles do not show a clear correlation between sediment calibre and slope angle; they do not rest at the angle-of-repose, and different kinds of sediment can rest at the same slope angle. At the transition from lower slope to toe- of-slope, the exponential equation fails to predict the present-day morphology. The toe-of-slope lies above the predicted trend. This is attributed to a drastic increase in turbidite deposition that provides additional sediment and raises the basin-floor profile above the predicted trend. The breaks between delta plain and slope are sharp, reflecting an abrupt change from transport by river flow and waves to gravity-driven transport. In these lakes, the base-level fluctuations relative to supply are small and insufficient to alter this sharp topographic break. The absence of sigmoidal profiles on the Swiss deltas is attributed to the high rate of progradation coupled with small fluctuations in base level.  相似文献   

Heat and momentum transport in an oak forest canopy     

Erwin Moritz 《Boundary-Layer Meteorology》1989,49(3):317-329

With the use of a sonic anemometer, vertical heat and momentum fluxes were measured at three different levels in an oak forest canopy. A quadrant analysis of the resulting data shows that approximately half of the transport occurs in extreme events lasting about 5 to 10% of the time. The partition of transport into momentum sweeps, bursts and interactions shows good agreement with existing data. The heat flux is analysed by observing the fluxes during the different momentum events and considering concurrent momentum and heat flux intensities by means of conditional probabilities. While low intensity (normal) events show similar probability distributions throughout the canopy, different structures appear at the three measurement heights for high intensity (extreme) events that can tentatively be explained by taking the temperature profile into account. This supports the idea that these events are coherent motions with scales comparable to the canopy height.  相似文献   

Late Holocene Moisture Changes in the Core Area of Arid Central Asia Reflected by Rock Magnetic Records of Glacier Lake Kalakuli Sediments in the Westernmost Tibetan Plateau and their Influences on the Evolution of Ancient Silk Road     

WU Xudong  LIU Xingqi  Erwin APPEL 《《地质学报》英文版》2020,94(3):658-667

The evolution of Ancient Silk Road(ASR) was deeply influenced by late Holocene moisture changes in Arid Central Asia(ACA). Nevertheless, controversies in Holocene moisture change pattern of ACA and poorly–constrained age models of related studies have made the discussion about late Holocene moisture changes in ACA and their influences on the evolution of ASR difficult. Recently, a high–resolution age model during the late Holocene was established for Kalakuli Lake, a small glacier lake located in the core area of ACA. A thorough rock magnetic investigation was carried out on Kalakuli Lake sediments based on this age model. The magnetic mineral assemblage of Kalakuli Lake sediments is still dominated by primary magnetite despite minor diagenetic effects. Comparisons of rock magnetic records to parameters previously used as indicator of glacier fluctuations suggest that clastic input to Kalakuli Lake was high(low) and magnetic grain size is relatively larger(smaller), when glaciers on Muztagh Ata advanced(retreated). The ARM/SIRM ratio, a magnetic grain size proxy, is directly related to lake hydrodynamics, which are ultimately controlled by glacier fluctuations on Muztagh Ata as the result of regional moisture changes. Late Holocene moisture changes indicated by the ARM/SIRM ratio are consistent with cool/wet and warm/dry oscillations indicated by the unweighted average of biomarker hydrogen isotopic data of the C_(26) and C_(28) n–alkanoic acids in a previous study about Kalakuli Lake, most moisture change records of the core area of ACA and winter insolation of the Northern Hemisphere, but opposite to Asian monsoon evolution. Given Asian monsoon and the westerlies are mutually inhibited, we propose that late Holocene moisture changes in the core area of ACA were controlled by the intensity of Asian monsoon versus the westerlies under the governance of solar insolation. Generally increased moisture since the late Holocene indicated by the ARM/SIRM ratio favored cultural exchange and integration between the western and the eastern Eurasia, which paved the way for the formation of ASR. Coincidence between significant increase in moisture at ～200 BC suggested by the ARM/SIRM ratio and the formation of ASR indicates moisture as an important factor that facilitated the formation of ASR. The onsets of three prosperity periods of ASR in the history generally correspond to periods when moisture was relatively high, nevertheless, stagnant periods of ASR do not coincide with periods when moisture was relatively low in the core area of ACA. Disorganized correlations between stagnant periods of ASR and moisture changes in the core area of ACA suggest that moisture is not the decisive factor influencing the evolution of ASR.  相似文献   

The excitation of the Chandler wobble     

S. K. Runcorn  G. A. Wilkins  E. Groten  H. Lenhardt  J. Campbell  R. Hide  B. F. Chao  A. Souriau  J. Hinderer  H. Legros  J. -L. Le Mouel  M. Feissel 《Surveys in Geophysics》1987,9(3-4):419-449

The cause- or causes-of the excitation of the Chandler wobble is one of the most intriguing problems in geophysics. As a result of one of the most valuable examples of an international programme, the positions of the pole have been determined since the late 19th century with remarkable accuracy. These data have always been accepted as of great importance in the study of the atmosphere, oceans and solid Earth. Recently, new techniques have greatly improved the accuracy with which the polar motion can be determined. Interpretation of the older data was made much more difficult because of their errors-for example the interesting suggestion that earthquakes were a cause of the excitation (by D. E. Smylie and L. Manshinha) could not be tested because their effects, if any, were lost in the noise. With the great improvement in the data it is now possible to suppose that comparable advances will be made in the theoretical interpretation. A discussion meeting at the Royal Astronomical Society on 8 May, 1987 on this topic was held and the following gives a short survey of this topic, consisting of brief summaries given by the speakers. This review is therefore a collective one which it is hoped will make more widely known these great technical advances and to fundamental interest of the phenomena of thepolar motion.  相似文献   

Comparison of geocentric orgins of global systems from uniformly distributed data     

H. Schaab  E. Groten 《Journal of Geodesy》1979,53(1):11-17

In contrast to tracking station fitting procedures where non-uniformly distributed data are applied to the determination of the relative locations of origins of specific coordinate systems (like GEM, SE etc.) uniformly distributed mean geoid values are used in an alternative approach. Those geoid data are obtained from sets of truncated spherical harmonic coefficients related to specific systems as GEM 8, SE IV, GRIM 2 etc. It is shown that relatively small (in general less than ±1 m) distances between the origin of GEM 8 and those of different other systems are found for recent models. The study corroborates the result obtained mainly in the US and reveals clear disagreement with previous investigations where separations between origins of the order of >10 m were detected.  相似文献   

    

Erwin Groten 《Journal of Geodesy》1975,49(1):41-56

The application of a Sartorius 4104 microbalance after Gast in vertical gradiometry was tested. A small mass of about 20 grams is suspended on thin fibers of different lengths Δℓ≤80 cm. From the weight difference of the small mass obtained at different levels along the plumb line the corresponding differences of gravity along the plumb line are inferred. The microbalance is mounted on a steal rack; measurements at constant low pressure (moderate vacuum) show the applicability of the balance as gravity difference sensor for field work. When environmental effects are further reduced (i,e, temperature is kept constant within ±0.1°C; pressure is controlled within 0.1 Torr etc.) the resolution of the balance can be fully exploited so a relative accuracy of ±10⁻⁹ should be feasible and for laboratory experiments should be of the order of a few parts in ±10⁻¹⁰. Vertical gravity gradients as observed on an improved moving platform with a LaCoste model G gravimeter are discussed. New possibilities of microgravimetry are pointed out. High precision observations and establishment of a system in an area of tectonic interest for detecting secular gravity changes are described. Paper presented at the meeting of the “International Gravity Commission”, Paris, September 1974.  相似文献   

The role of high-precision gravimetry in detecting and monitoring recent crustal movements in view of the African situation     

E. Groten 《Journal of Geodynamics》1987,7(3-4)

High precision relative gravimetry can play a dual role in the study of vertical recent crustal movemen: exploring and monitoring. A number of G-meters of LCR type have been calibrated over the full measurement range so that they can be used in almost any part of African. Recent high precision measurements in desert, tropical and subtropical zones reveal clearly that even under unfavorable climatical and transportation conditions precise gravity is available within ± 10 to 20 microgal accuracy.  相似文献