Moisture origin and stable isotope characteristics of precipitation in southeast Siberia     

Svetlana S. Kostrova  Hanno Meyer  Francisco Fernandoy  Martin Werner  Pavel E. Tarasov 《水文研究》2020,34(1):51-67

The paper presents oxygen and hydrogen isotopes of 284 precipitation event samples systematically collected in Irkutsk, in the Baikal region (southeast Siberia), between June 2011 and April 2017. This is the first high-resolution dataset of stable isotopes of precipitation from this poorly studied region of continental Asia, which has a high potential for isotope-based palaeoclimate research. The dataset revealed distinct seasonal variations: relatively high δ¹⁸O (up to −4‰) and δD (up to −40‰) values characterize summer air masses, and lighter isotope composition (−41‰ for δ¹⁸O and −322‰ for δD) is characteristic of winter precipitation. Our results show that air temperature mainly affects the isotope composition of precipitation, and no significant correlations were obtained for precipitation amount and relative humidity. A new temperature dependence was established for weighted mean monthly precipitation: +0.50‰/°C (r² = 0.83; p <.01; n = 55) for δ¹⁸O and +3.8‰/°C (r² = 0.83, p < 0.01; n = 55) for δD. Secondary fractionation processes (e.g., contribution of recycled moisture) were identified mainly in summer from low d excess. Backward trajectories assessed with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicate that precipitation with the lowest mean δ¹⁸O and δD values reaches Irkutsk in winter related to moisture transport from the Arctic. Precipitation originating from the west/southwest with the heaviest mean isotope composition reaches Irkutsk in summer, thus representing moisture transport across Eurasia. Generally, moisture transport from the west, that is, the Atlantic Ocean predominates throughout the year. A comparison of our new isotope dataset with simulation results using the European Centre/Hamburg version 5 (ECHAM5)-wiso climate model reveals a good agreement of variations in δ¹⁸O (r² = 0.87; p <.01; n = 55) and air temperature (r² = 0.99; p <.01; n = 71). However, the ECHAM5-wiso model fails to capture observed variations in d excess (r² = 0.14; p < 0.01; n = 55). This disagreement can be partly explained by a model deficit of capturing regional hydrological processes associated with secondary moisture supply in summer.  相似文献   

Analytical theories of satellite motion constructed with a new package of formula manipulation and compared with numerical integration     

O. Meyer  B. Reichhoff  M. Schneider 《Celestial Mechanics and Dynamical Astronomy》2000,76(2):121-129

Specialized to the Lie series based perturbation method of Kirchgraber and Stiefel (1978) a new computer algebra package called ANALYTOS has been developed for constructing analytical orbital theories either in noncanonical or canonical form. We present results on the (extended) Main Problem of orbital theory of artificial earth satellites and related issues. The order of the solutions achieved is generally one order higher than those known from literature. Moreover, the analytical orbits have been checked succesfully against precise numerical ephemerides. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Radiation Fog Prediction Using a Simple Numerical Model   总被引：1，自引：0，他引：1  

W. D. Meyer  G. V. Rao 《Pure and Applied Geophysics》1999,155(1):57-80

—A simple one-dimensional numerical-analytical model was developed by Meyer and Rao (1995) to predict the onset of radiation fog. The model computes radiative cooling and turbulent diffusion of heat and vapor through the lower boundary layer and produces heat and vapor fluxes at the soil–atmosphere interface. The model is designed for Air Force forecasters who have access to a personal computer, an early evening surface observation of the dry bulb and dewpoint temperature, wind speed, the lapse rate in the upper boundary layer, and the previous 24-h precipitation amount. These initial data are used to predict the diurnal variation of the dry bulb and dewpoint temperatures at 10 m above the surface. In accordance with conventional synoptic observing practices, fog is defined as a restriction of the surface visibility generally to less than 1000 m. Fog is assumed to occur in the model predictions when the dewpoint depression falls to less than 1°C. Observations, from several Air Force bases for selected days when fog was observed to occur, were used to test the model. The present model with default parameters appears to predict the onset of fog slightly ahead of its occurrence. Better verification results are expected when site-relevant parameters are used in model predictions.  相似文献   

Olivine-rich units in the Fongen–Hyllingen Intrusion, Norway: implications for magma chamber processes     

Gurli B. Meyer  J. Richard Wilson 《Lithos》1999,47(3-4):157-179

The Fongen–Hyllingen Intrusion (FHI) is considered to have crystallised from stratified magma residing in a bowl-shaped magma chamber. Seven olivine-rich units, representing the most primitive cumulates in the central part of the intrusion, are associated with compositional reversals and are interpreted as having formed at the lowest part of the magma chamber floor. Based on phase-relationships, the crystallisation order is explained in terms of magma mixing and fractional crystallisation. Repeated influxes of small volumes of dense, primitive magma at the base of the chamber had a major impact on the crystallising assemblage on the local floor and a decreasing effect towards the flanks of the chamber. This was due to the small volume of replenishing magma, the geometry of the chamber and the consequent restriction of magma mixing to the deepest part of the chamber where the new magma was emplaced. It is estimated that the chamber floor sloped as little as 1–2°, but this was sufficient to give widely different cumulate sequences near the bottom of the chamber and on the flanks.  相似文献   

Book reviews     

Manfred Bauer  Elmar R. Reiter 《Meteorology and Atmospheric Physics》1999,69(3-4):239-242

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Deep-seated gravitational slope deformation (DSGSD) and slow-moving landslides in the southern Tien Shan Mountains: new insights from InSAR,tectonic and geomorphic analysis     

Kanayim Teshebaeva  Helmut Echtler  Bodo Bookhagen  Manfred Strecker 《地球表面变化过程与地形》2019,44(12):2333-2348

We investigated deep-seated gravitational slope deformation (DSGSD) and slow mass movements in the southern Tien Shan Mountains front using synthetic aperture radar (SAR) time-series data obtained by the ALOS/PALSAR satellite. DSGSD evolves with a variety of geomorphological changes (e.g. valley erosion, incision of slope drainage networks) over time that affect earth surfaces and, therefore, often remain unexplored. We analysed 118 interferograms generated from 20 SAR images that covered about 900 km². To understand the spatial pattern of the slope movements and to identify triggering parameters, we correlated surface dynamics with the tectono-geomorphic processes and lithologic conditions of the active front of the Alai Range. We observed spatially continuous, constant hillslope movements with a downslope speed of approximately 71 mm year⁻¹ velocity. Our findings suggest that the lithological and structural framework defined by protracted deformation was the main controlling factor for sustained relief and, consequently, downslope mass movements. The analysed structures revealed integration of a geological/structural setting with the superposition of Cretaceous–Paleogene alternating carbonatic and clastic sedimentary structures as the substratum for younger, less consolidated sediments. This type of structural setting causes the development of large-scale, gravity-driven DSGSD and slow mass movement. Surface deformations with clear scarps and multiple crest lines triggered planes for large-scale deep mass creeps, and these were related directly to active faults and folds in the geologic structures. Our study offers a new combination of InSAR techniques and structural field observations, along with morphometric and seismologic correlations, to identify and quantify slope instability phenomena along a tectonically active mountain front. These results contribute to an improved natural risk assessment in these structures. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd  相似文献   

Geology of Fortrose and eastern Inverness District. Memoir for 1:50 000 Geological Sheet 84W (Scotland) by T.P. Fletcher,C.A. Auton,A.J. Highton,J.W.Merritt,S. Robertson and K.E. Rollin. British Geological Survey,Keyworth, Nottingham 1996 (137pp). £50 ISBN 0-11-884511-X     

Klaus-Dieter Meyer 《第四纪科学杂志》1998,13(3):282-282

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The celestial mechanics approach: theoretical foundations   总被引：4，自引：3，他引：1  

Gerhard Beutler  Adrian Jäggi  Leoš Mervart  Ulrich Meyer 《Journal of Geodesy》2010,84(10):605-624

Gravity field determination using the measurements of Global Positioning receivers onboard low Earth orbiters and inter-satellite measurements in a constellation of satellites is a generalized orbit determination problem involving all satellites of the constellation. The celestial mechanics approach (CMA) is comprehensive in the sense that it encompasses many different methods currently in use, in particular so-called short-arc methods, reduced-dynamic methods, and pure dynamic methods. The method is very flexible because the actual solution type may be selected just prior to the combination of the satellite-, arc- and technique-specific normal equation systems. It is thus possible to generate ensembles of substantially different solutions—essentially at the cost of generating one particular solution. The article outlines the general aspects of orbit and gravity field determination. Then the focus is put on the particularities of the CMA, in particular on the way to use accelerometer data and the statistical information associated with it.  相似文献   

Environmental Perception,Sense of Place,and Residence Time in the Okavango Delta,Botswana     

Amelia C. Eisenhart  Kelley A. Crews Meyer  Brian King  Kenneth R. Young 《The Professional geographer》2019,71(1):109-122

Integral to the geographic discipline are cross-cultural analyses, many of which use languages outside of the researcher’s own. There are few analyses, however, that address issues of translation that are inherently geographic; namely, that language is understood as a manifestation of place and culture. This article argues that the results of environmental interviews must be interpreted through a lens that evaluates how the translation of a word, or even a concept, is understood differentially based on one’s sense of place. Interviews were conducted in three of the Etsha villages situated in the Okavango Delta, Botswana, comparing perceptions of changes in both the local area and the flooding regime. Findings show qualitatively and quantitatively how residents perceive environmental change in light of their residential histories and their production of place. These results highlight that environmental change in an area is perceived in the context of previous residences, including the length of time spent in residence and the environmental characterization of that place. The process of interviewing regarding such change, especially when translation is necessary, should therefore proceed by incorporating inquiries about previous residences and the environments of those areas to correctly contextualize environmental change in a particular area.  相似文献   

Scientific detector workshop 2022 on-sky performance verification of near-infrared e−APD technology for wavefront sensing and demonstration of e−APD pixel performance to improve the sensitivity of large science focal planes     

Gert Finger  Frank Eisenhauer  Reinhard Genzel  Christopher Mandla  Ian Baker  Domingo Alvarez  Antonio Amorim  Wolfgang Brandner  Christophe Dupuy  Casey Deen  Derek Ives  Leander Mehrgan  Manfred Meyer  Karin Perraut  Guy Perrin  Jörg Stegmeier  Christian Straubmeier  Harald J. Weller  Vincent Isgar 《Astronomische Nachrichten》2023,344(8-9):e20230069

Near-infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry require the development of high-speed sensors. Because of the high speed, a large analog bandwidth is required. The short exposure times result in small signal levels which require noiseless detection. Both requirements cannot be met by state-of-the-art conventional CMOS technology of near-infrared arrays as has been attempted previously. A total of five near-infrared SAPHIRA 320 × 256 pixel HgCdTe e⁻APD arrays have been deployed in the wavefront sensors and in the fringe tracker of the VLTI instrument GRAVITY. The current limiting magnitude for coherent exposures with GRAVITY is m_k = 19, which is made possible with ADP technology. New avalanche photo-diode array (APD) developments since GRAVITY include the extension of the spectral sensitivity to the wavelength range from 0.8 to 2.5 μm. After GRAVITY a larger format array with 512 × 512 pixels has been developed for both AO applications at the ELT and for long integration times. Since dark currents of <10⁻³ e⁻/s have been demonstrated with 1Kx1K e⁻APD arrays and 2Kx2K e⁻APD arrays have already been developed, the possibilities and adaptations of e⁻APD technology to provide noiseless large-format science-grade arrays for long integration times are also discussed.  相似文献