Application of wavelet transformation to determine wavelengths and phase velocities of gravity waves observed by lidar measurements     

R. Werner  K. Stebel  G.H. Hansen  U. Blum  U.-P. Hoppe  M. Gausa  K.-H. Fricke 《Journal of Atmospheric and Solar》2007,69(17-18):2249

During the last two decades, important advances have been made in the investigation of gravity waves. However, more efforts are needed to study certain aspects of gravity waves. In the real atmosphere, gravity waves occur with different properties at different altitudes and, most often, simultaneously. In this case, when there is more than one dominant wave, the determination of gravity wave characteristics, such as the vertical wavelength and the phase velocity, is difficult. The interpretation of temperature perturbation plots versus the altitude and time as well as the application of the Fourier spectral analysis can produce errors.Exact knowledge of the wave characteristics is important both for determination of other characteristics, for example, the horizontal wave components, and for study of wave climatology. The wavelet analysis of vertical temperature profiles allows one to examine the wave's location in space. Up to now, gravity waves have been studied mainly by continuous wavelet transformation to determine dominant waves. We apply wavelet analysis to a time series of temperature profiles, observed by the ALOMAR ozone lidar at Andoya, Norway, and by the U. Bonn lidar system at ESRANGE, Sweden, both for determination of the dominant waves and for specifying the vertical wavelengths and the vertical component of the phase velocities. For this purpose, the wavelet amplitude spectra and the wavelet phase spectra are filtered and Hovmöller diagrams for dominant wavelengths are constructed. The advantage of this type of diagrams is that they give clear evidence for the localization of the dominant waves in space and time and for the development of their phase fronts.  相似文献   

Rainer Friedrich and Stefan Reis, editors: Tropospheric Ozone Abatement; Developing Efficient Strategies for the Reduction of Ozone Precursor Emissions in Europe     

Wolfgang Fricke 《Journal of Atmospheric Chemistry》2001,39(2):216-218

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The ALOMAR Rayleigh/Mie/Raman lidar: objectives, configuration, and performance     

U. von Zahn  G. von Cossart  J. Fiedler  K. H. Fricke  G. Nelke  G. Baumgarten  D. Rees  A. Hauchecorne  K. Adolfsen 《Annales Geophysicae》2000,18(7):815-833

We report on the development and current capabilities of the ALOMAR Rayleigh/Mie/Raman lidar. This instrument is one of the core instruments of the international ALOMAR facility, located near Andenes in Norway at 69°N and 16°E. The major task of the instrument is to perform advanced studies of the Arctic middle atmosphere over altitudes between about 15 to 90 km on a climatological basis. These studies address questions about the thermal structure of the Arctic middle atmosphere, the dynamical processes acting therein, and of aerosols in the form of stratospheric background aerosol, polar stratospheric clouds, noctilucent clouds, and injected aerosols of volcanic or anthropogenic origin. Furthermore, the lidar is meant to work together with other remote sensing instruments, both ground- and satellite-based, and with balloon- and rocket-borne instruments performing in situ observations. The instrument is basically a twin lidar, using two independent power lasers and two tiltable receiving telescopes. The power lasers are Nd:YAG lasers emitting at wavelengths 1064, 532, and 355 nm and producing 30 pulses per second each. The power lasers are highly stabilized in both their wavelengths and the directions of their laser beams. The laser beams are emitted into the atmosphere fully coaxial with the line-of-sight of the receiving telescopes. The latter use primary mirrors of 1.8 m diameter and are tiltable within 30° off zenith. Their fields-of-view have 180 rad angular diameter. Spectral separation, filtering, and detection of the received photons are made on an optical bench which carries, among a multitude of other optical components, three double Fabry-Perot interferometers (two for 532 and one for 355 nm) and one single Fabry-Perot interferometer (for 1064 nm). A number of separate detector channels also allow registration of photons which are produced by rotational-vibrational and rotational Raman scatter on N₂ and N₂+O₂ molecules, respectively. Currently, up to 36 detector channels simultaneously record the photons collected by the telescopes. The internal and external instrument operations are automated so that this very complex instrument can be operated by a single engineer. Currently the lidar is heavily used for measurements of temperature profiles, of cloud particle properties such as their altitude, particle densities and size distributions, and of stratospheric winds. Due to its very effective spectral and spatial filtering, the lidar has unique capabilities to work in full sunlight. Under these conditions it can measure temperatures up to 65 km altitude and determine particle size distributions of overhead noctilucent clouds. Due to its very high mechanical and optical stability, it can also employed efficiently under marginal weather conditions when data on the middle atmosphere can be collected only through small breaks in the tropospheric cloud layers.  相似文献   

宁芜盆地火山-次火山岩的锆石U-Pb年龄、Hf同位素组成及其地质意义   总被引：40，自引：23，他引：17  

侯可军  袁顺达 《岩石学报》2010,26(3):888-902

宁芜火山盆地是长江中下游重要的火山盆地之一,在盆地内自下而上依次发育龙王山组、大王山组、姑山组和娘娘山组火山岩和若干个同源次火山岩或小侵入岩体。本文对宁芜盆地火山-次火山岩进行了详细的锆石U-Pb年龄和Hf同位素地球化学研究。研究结果表明,大王山组粗安岩锆石U-Pb年龄为130.3±0.9Ma,姑山组两个粗安岩锆石U-Pb年龄分别为128.2±1.3Ma和128.5±1.8Ma,另外三个侵入岩年龄分别为127.1±1.2Ma、128.3±0.6Ma和128.2±1.0Ma,均为早白垩纪。综合前人成果,认为长江中下游地区火山盆地内火山活动的时限在135～124Ma之间,不存在侏罗纪岩浆活动。宁芜盆地火山岩和侵入岩的锆石176Hf/177Hf值在0.282502～0.282673范围内,εHf(t)变化为-6.9～-0.7,显示岩浆源自于岩石圈富集地幔部分熔融并在上升过程中受地壳物质的混染,为岩石圈伸展环境的产物。  相似文献   

Morphology and dynamics of the intertidal floodplain along the Amazon tidal river     

Aaron T. Fricke  Charles A. Nittrouer  Andrea S. Ogston  Daniel J. Nowacki  Nils E. Asp  Pedro W. M. Souza Filho 《地球表面变化过程与地形》2019,44(1):204-218

Depositional environments along the tidal river downstream of Óbidos have been proposed as important sinks for up to one third of the sediment discharge from the Amazon River. However, the morphology of the intertidal floodplain and the dynamics of sediment exchange along this reach have yet to be described. River-bank surveys in five regions along the Amazon tidal river reveal a distinct transition in bank morphology between the upper, central and lower reaches of the tidal river. The upper tidal-river floodplain is defined by prominent natural levees that control the transfer of water and sediment between the mainstem Amazon River and its floodplain. Greater tidal influence in the central tidal river suppresses levee development, and tidal currents increase sediment transport into the distal parts of the floodplain. In the lower tidal river, the floodplain morphology closely resembles marine intertidal environments (e.g. mud flats, salt marshes), with dendritic tidal channels incising elevated vegetated flats. Theory, morphology and geochronology suggest that the dynamics of sediment delivery to the intertidal floodplain of the Amazon tidal river vary along its length due to the relative influence and coupling of fluvial and tidal dynamics. © 2018 John Wiley & Sons, Ltd.  相似文献   

Beiträge der Berliner Sternwarte zu Erkenntnissen auf dem Gebiet der klassischen Astronomie     

W. Fricke 《Astronomische Nachrichten》1983,304(1):1-6

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Friedrich Wilhelm Bessel (1784–1846)     

Fricke  Walter 《Astrophysics and Space Science》1985,110(1):11-19

May I first express my warmest thanks to the organizers of the Conference for having invited me to present a brief bibliographic report on the great astronomer F. W. Bessel. You have given me a welcome opportunity to express an appreciation of Bessel's work which has marked the beginning of research on the motion of stars and which was pioneer work on astrometric binaries and on the determination of stellar distances. Bessel has established the first celestial coordinate system which approximates an inertial system, and my colleagues and I at Heidelberg in establishing an improved fundamental reference system, the FK5, have had to review again some of Bessel's pioneer contributions to this field, and such contributions shall be mentioned later. My talk shall be divided into the following parts: (1) Bessel's course of life and family; (2) Education in astronomy in Bremen; (3) Fundamenta Astronomiae; (4) Fundamental observations at the Königsberg Observatory (or according to S. Newcomb (1906): the German School of Astrometry); (5) 61 Cygni; (6) Bibliography of Bessel's original works.Communication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wilhelm Bessel (1784–1846).  相似文献   

Oxygen and hydrogen isotope evidence for meteoric water infiltration during mylonitization and uplift in the Ruby Mountains-East Humboldt Range core complex,Nevada     

Henry C. Fricke  Stephen M. Wickham  James R. O'Neil 《Contributions to Mineralogy and Petrology》1992,111(2):203-221

Stable isotope analyses of rocks and minerals associated with the detachment fault and underlying mylonite zone exposed at Secret Creek gorge and other localities in the Ruby-East Humboldt Range metamorphic core complex in northeastern Nevada provide convincing evidence for meteoric water infiltration during mylonitization. Whole-rock ¹⁸O values of the lower plate quartzite mylonites (95% modal quartz) have been lowered by up to 10 per mil compared with structurally lower, compositionally similar, unmylonitized material. Biotite from these rocks has D values ranging from -125 to -175, compared to values of -55 to-70 in biotite from unmylonitized rocks. Mylonitized leucogranites have large disequilibrium oxygen isotope fractionations ( ^{quartz-feldspar} up to 8 per mil) relative to magmatic values ( ^{quartz-feldspar}1 to 2 per mil)). Meteoric water is the only major oxygen and hydrogen reservoir with an isotopic composition capable of generating the observed values. Fluid inclusion water from unstrained quartz in silicified breccia has a D value of-119 which provides a plausible estimate of the D of the infiltrating fluid, and is similar to the isotopic composition of present-day and Tertiary local meteoric water. The quartzite mylonite biotites would have been in equilibrium with such a fluid at temperatures of 480–620° C, similar to independent estimates of the temperature of mylonitization. The relatively high temperatures required for isotopic exchange between quartz and water, the occurrence of fluid inclusion trails and deformed veins in quartzite mylonites, and the spatial association of the low-¹⁸O, low-D rocks with the shear zone all constrain isotopic exchange to the mylonitic (plastic) deformation event. These observations suggest thata significant amount of meteoric water infiltrated the shear zone during mylonitization to depths of at least 5 to 10 km below the surface. The depth of penetration of meteoric fluids into the lower plate mylonites was at least 70 meters below the detachment fault. In contrast, the upper-plate unmylonitized fault slices are dominated by brittle fracture and are often intensely veined (carbonates) or silicified (volcanic rocks and breccias). The fluids associated with the veining and silicification were also meteoric as evidenced by low ¹⁸O values of the veins, which are often 10 per mil lower than the adjacent carbonate matrix, and the exceptionally low ¹⁸O values (down to-4.4) of the breccias. Several previous studies have documented the infiltration of meteoric fluids into the brittley deformed upper plate rocks of core complexes, but this study provides convincing evidence that surface fluids have penetrated lower plate rocks undergoing plastic deformation. It is proposed that infiltration took place as the shear zone began the transition from plastic flow to brittle fracture while the lower plate rocks were being uplifted. During this period, plastic flow and brittle fracture were operating simultaneously, perhaps allowing upper plate meteoric fluids to be seismically pumped down into the lower plate mylonites.  相似文献   

Recent anomalies of mean temperature of 12 consecutive months – Germany, Europe, Northern Hemisphere     

Z. W. Kundzewicz  F.-W. Gerstengarbe  H. Österle  P. C. Werner  W. Fricke 《Theoretical and Applied Climatology》2009,95(3-4):417-422

Anomalies of mean air temperature of 12 consecutive months were detected recently at a number of spatial scales: from local via national and continental, to hemispheric. At all these spatial scales, pre-2007 records were exceeded by considerable margins. The recent rise in the mean temperature of 12 consecutive months at several scales has remained largely unnoticed, because the 12-month means are seldom analyzed. Broad attention is typically focused on monthly, seasonal and annual temperatures. Analysis of shifted 12-month periods helps spot peculiar 12-month episodes with remarkable temperature anomalies that do not coincide with a calendar year. Introducing 12-month running mean temperatures into the global warming debate can prove useful.  相似文献   

西藏南部晚始新世打拉埃达克质花岗岩及其构造动力学意义   总被引：9，自引：7，他引：2  

谢克家  曾令森  刘静  高利娥 《岩石学报》2010,26(4):1016-1026

打拉二云母花岗岩岩体位于雅拉香波穹隆的东南,侵入到中生代以前的变质岩系(眼球状花岗质片麻岩和石榴黑云母片麻岩)和特提斯沉积岩(页岩和砂岩)中,主要由石英、斜长石、钾长石、黑云母和白云母组成,形成于～44.3Ma。打拉二云母花岗岩地球化学特征表明:打拉花岗岩具有高Al_2O_3(16.0%～17.0%)、Na_2O/K_2O(1.2)以及A/CNK比值(1.05),表明打拉花岗岩为富钠过铝质花岗岩;轻稀土(LREE)富集,重稀土(HREE)相对亏损,HREE中的Ho到Lu元素有变平的特征((Ho/Lu)_N=1.11～1.46);具有微弱或无Eu异常,Eu/Eu~*=0.87～0.95;较高的初始Sr同位素比值(~(87)Sr/~(86)Sr(i)=0.71754～0.71785)和较低的初始Nd比值(ε_(Nd)(i)=-9.15～-12.4)。打拉花岗岩具有高Sr含量(为355×10~(-6)～416×10~(-6))和Sr/Y的比值(59.1～71.5)、高La/Yb比值、低Y及HREE亏损的特征,与埃达克质花岗岩类似。上述特征表明打拉花岗岩是在较高压力条件下,以角闪岩为主的深部岩石部分熔融的结果。  相似文献