Readout Techniques for Drift and Low Frequency Noise Rejection in Infrared Arrays     

Gert Finger  Reinhold J. Dorn  Alan W. Hoffman  Hamid Mehrgan  Manfred Meyer  Alan F. M. Moorwood  Joerg Stegmeier 《Experimental Astronomy》2002,14(2):117-127

Three different methods are presented to subtract thermal drifts and low-frequency noise from the signal of infrared array. The first is dead pixels with open Indium bumps, the second is reference output as implemented on the Hawaii2 multiplexer, and the third is dark pixels to emulate reference cells having a capacity connected to the gate of the unit cell field-effect transistor (FET). The third method is the most effective and yields a reduction in readout noise from15.4–9.4 erms. A novel method will be described to extend this readout technique to the Aladdin 1 K × 1 K InSb array. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Tritium profiles in the Weddell Sea     

Reinhold Bayer  Peter Schlosser 《Marine Chemistry》1991,35(1-4)

Tritium data were collected between 1985 and 1987 on several cruises of the German research icebreaker “Polarstern” to the Weddell Sea. Maximum tritium concentrations in the surface waters are of the order of 200 mTU. The minimum values observed in the Weddell Sea Deep Water at about 1000 m depth are about 15–40 mTU. The bottom waters show tritium concentrations of about 70–100 mTU in the central gyre, increasing to about 120 mTU in the northwestern corner of the Weddell Sea. The overflowing Ice Shelf Water observed on the continental slope west of the Filchner Depression has tritium concentrations close to those of the surface waters, indicating rapid renewal of this water mass. The data reflect the rapid renewal of the bottom waters in the northwestern corner of the Weddell Sea and the mixing of bottom water from this boundary current into the bottom waters of the central Weddell Gyre.  相似文献   

The distribution of tritium and CFCs in the Weddell Sea during the mid-1980s     

Manfred Mensch  Reinhold Bayer  John L. Bullister  Peter Schlosser  Ray F. Weiss 《Progress in Oceanography》1996,38(4):377-388

Transient tracer data (tritium, CFC11 and CFC12) from the southern, central and northwestern Weddell Sea collected during Polarstern cruises ANT III-3, ANT V-2/3/4 and during Andenes cruise NARE 85 are presented and discussed in the context of hydrographic observations. A kinematic, time-dependent, multi-box model is used to estimate mean residence times and formation rates of several water masses observed in the Weddell Sea.Ice Shelf Water is marked by higher tritium and lower CFC concentrations compared to surface waters. The tracer signature of Ice Shelf Water can only be explained by assuming that its source water mass, Western Shelf Water, has characteristics different from those of surface waters. Using the transient nature of tritium and the CFCs, the mean residence time of Western Shelf Water on the shelf is estimated to be approximately 5 years. Ice Shelf Water is renewed on a time scale of about 14 years from Western Shelf Water by interaction of this water mass with glacial ice underneath the Filchner-Ronne Ice shelf. The Ice Shelf Water signature can be traced across the sill of the Filchner Depression and down the continental slope of the southern Weddell Sea. On the continental slope, new Weddell Sea Bottom Water is formed by entrainment of Weddell Deep Water and Weddell Sea Deep Water into the Ice Shelf Water plume. In the northwestern Weddell Sea, new Weddell Sea Bottom Water is observed in two narrow, deep boundary currents flowing along the base of the continental slope. Classically defined Weddell Sea Bottom Water (θ ≤ −0.7°C) and Weddell Sea Deep Water (−0.7°C ≤ θ ≤ 0°C) are ventilated from the deeper of these boundary currents by lateral spreading and mixing. Model-based estimates yield a total formation rate of 3.5Sv for new Weddell Sea Bottom Water (θ = −1.0°C) and a formation rate of at least 11Sv for Antarctic Bottom Water (θ = −0.5°C).  相似文献   

The GRECOS operating system of the GCT     

Axel D. Wittmann  Reinhold Kroll 《Astrophysics and Space Science》1990,171(1-2):357-359

The computer operating system of the Gregory Coudé Telescope (GCT) at Observatorio del Teide is described. The GRECOS command language provides the user with a flexible means of operating both telescope and spectrograph, to execute complex measuring sequences, and to handle and display his observational data.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.  相似文献   

Geochemical and isotope data from the Acatlán Volcanic Field, western Trans-Mexican Volcanic Belt: Origin and evolution     

Guadalupe Maldonado-Snchez  Peter Schaaf 《Lithos》2005,82(3-4):455-470

The Quaternary Acatlán Volcanic Field (AVF) is located at the western edge of the Trans-Mexican Volcanic Belt (TMVB). This region is related to the subduction of the Pacific Cocos and Rivera plates beneath the North American plate since the late Miocene. AVF rocks are products of Pleistocene volcanic activity and include lava flows, domes, erupted basaltic andesite, trachyandesite, trachydacite, and rhyolite of calc–alkaline affinity. Most rocks show depletion in high field-strength elements and enrichment in large ion lithophile elements and light rare earth elements as is typical for magmas in subduction-related volcanic arcs. ⁸⁷Sr/⁸⁶Sr values range from 0.70361 to 0.70412, while Nd values vary from +2.3 to +5.2. Sr–Nd isotopic data plot along the mantle array. On the other hand, lead isotope compositions (²⁰⁶Pb/²⁰⁴Pb=18.62–18.75, ²⁰⁷Pb/²⁰⁴Pb=15.57–15.64, and ²⁰⁸Pb/²⁰⁴Pb=38.37–38.67) give evidence for combined influences of the upper mantle, fluxes derived from subducted sediments, and the upper continental crust involved in magma genesis at AVF. Additionally δ¹⁸O whole rock analyses range from +6.35‰ in black pumice to +10.9‰ in white pumice of the Acatlán Ignimbrite. A fairly good correlation is displayed between Sr as well as O isotopes and SiO₂ emphasizing the effects of crustal contamination. Compositional and isotopic data suggest that the different AVF series derived from distinct parental magmas, which were generated by partial melting of a heterogeneous mantle source.  相似文献   

El Ventorrillo,a paleostructure of Popocatépetl volcano: insights from geochronology and geochemistry     

G. Sosa-Ceballos  J. L. Macías  F. García-Tenorio  P. Layer  P. Schaaf  G. Solís-Pichardo  J. L. Arce 《Bulletin of Volcanology》2015,77(10):1-20

  相似文献   

The Juchatengo complex: an upper-level ophiolite assemblage of late Paleozoic age in Oaxaca,southern Mexico     

Grajales-Nishimura  José Manuel  Ramos-Arias  Mario Alfredo  Solari  Luigi  Murillo-Muñetón  Gustavo  Centeno-García  Elena  Schaaf  Peter  Torres-Vargas  Ricardo 《International Journal of Earth Sciences》2018,107(3):1005-1031

International Journal of Earth Sciences - The Juchatengo complex (JC) suite is located between the Proterozoic Oaxacan complex to the north and the Xolapa complex to the south, and was amalgamated...  相似文献   

A simulation model of how life history strategies mediate pollution effects on fish populations     

W. E. Schaaf  D. S. Peters  L. Coston-Clements  D. S. Vaughan  C. W. Krouse 《Estuaries and Coasts》1993,16(4):697-702

Pollution effects on fish populations were estimated with a simulation model, using Leslie matrices. Results from changing only first-year survival rate (S_o) have already been published (Schaaf et al. 1987). This paper explores the effects of perturbing both S_o and the adult survival rate (S_i) for 12 spatial-temporal stocks. Most stocks examined are more sensitive to permanent change in S_i than to changes in S_o. The relative importance of these two rates in determining the population growth rate (λ) depends upon the age distribution of the expected lifetime egg production of age i females (V_i). In turn, the vector V_i, as measured by its mean and standard deviation, is shown to vary among geographic or temporal stocks of a single species. Hence, we quantify the impact on population size of destroying a fixed percentage of habitat, relative to where and when it occurs (i.e., relative impact on S_i and S_o). For example, destroying 1% of the Atlantic menhaden habitat would reduce λ by 0.8% and the population by 8.0% in 10 yr, if the impact affected only adults (e.g., offshore in winter). If the 1% habitat destruction all occurred in the estuaries, affecting juveniles as well, λ would be reduced by almost 5%, and in 10 yr drive the population down to 58% of its former equilibrium. We show that knowledge of the mean and variance of the age distribution of V_i permits prediction of relative sensitivity among species to pollution. Within species, this knowledge of V_i permits comparison of the effects of impacting different life stages and at different times and places.  相似文献   

Element budgets of pine stands on lignite and pyrite containing mine soils     

Martin Gast  Wolfgang Schaaf  Joerg Scherzer  Rudolf Wilden  Bernd U. Schneider  Reinhard F. Hüttl 《Journal of Geochemical Exploration》2001,73(2):196

To analyze the development of pine ecosystems on lignite and pyrite containing mine soils, four pine stands with ages of 3–35 years were investigated in a chronosequence approach. Bulk precipitation, throughfall and soil solution in depths of 20, 40, 70 and 100 cm were studied over a three-year period to determine element fluxes in these forest ecosystems on extreme acidic and saline soils.Element budgets are controlled by the processes induced by pyrite oxidation such as intensive weathering of primary minerals, precipitation and leaching of secondary phases.Despite low water fluxes, element outputs can reach extraordinary high values due to very high concentrations in the soil solution. Although element outputs decrease drastically with stand age, respectively, site age, they exceed those of comparable pine stands on non-mine sites. Nitrogen release from the lignite fraction represents a special characteristic of the examined substrates. Nitrogen losses beneath the rooted zone can be 34 kg N ha⁻¹ yr⁻¹ in 100 cm depth. Element input and output in the examined ecosystems are far from balance. Closed cycling of nutrients seems to be recognizable in the case of potassium.  相似文献   

Das luftelektrische Erscheinungsbild des Südföhns in den Nordalpen nach synoptisch-klimatologischen Untersuchungen im Wettersteingebirge 1955 bis 1959     

Reiter  Reinhold 《Meteorology and Atmospheric Physics》1960,12(1):72-124

Zusammenfassung Die Arbeit bringt alle Erfahrungen über Föhn in luftelektrischer Hinsicht, die im Laufe von fünf Jahren durch Registrierungen, Messungen und Beobachtungen vor allem im Raum des Wettersteingebirges bei Garmisch-Partenkirchen gewonnen wurden. Es stand hierfür ein Netz von sieben ständig betriebenen Stationen zur Verfügung, zwei weitere Stationen wurden 1958 während einer zweimonatigen Exkursion auf dem Zugspitzplatt (2600 m NN) unterhalten. Diese neun Stationen lagen in einigermaßen gleichmäßiger Höhenstaffelung zwischen 675 und 2963 m NN. Ihre Basisentfernungen waren relativ gering. Alle neun Stationen registrierten den luftelektrischen Potentialgradienten, vier der sieben ständigen sowie eine der beiden vorübergehenden Stationen registrierten zusätzlich den luftelektrischen Leitungsstrom. Als weitere Elemente des Komplexes Luftelektrizität und Aerosol wurden registriert bzw. gemessen: positive und negative Kleinionen, positive und negative Luftleitfähigkeit, natürliche und künstliche Radioaktivität der Luft, Kondensationskerne (Aitkenkerne), Luftverunreinigung, Spitzenstrom und Atmospherics. Ein tragendes Grundprinzip der Arbeit ist die synoptische Verwertung der Daten des relativ dichten und auch in die Vertikale reichenden Stationsnetzes, mit dessen Hilfe ein dreidimensionaler Ausschnitt der Atmosphäre überschaubar wird. Die Einheitlichkeit der verwendeten Methoden sowohl in der räumlichen als auch in der über Jahre gehenden zeitlichen Erstreckung trägt zur Festigung der Ergebnisse und Schlüsse bei.Aus dem Beobachtungsmaterial wird abgeleitet, daß Föhnlagen sich nicht dadurch auszeichnen, daß sich bestimmte luftelektrische Einzelgrößen dabei besonders oder außergewöhnlich verhalten würden. Typisch für den Föhn ist vielmehr ein ganz bestimmter Akkord der luftelektrischen (und meteorologischen) Elemente, wobei sich innerhalb des Stationsnetzes wiederum typische Variationen bemerkbar machen.Luftelektrisch gesehen, konnten zwei Föhntypen unterschieden werden: Bei Typ I sind die Kurven des Potentialgradienten und des Leitungsstromes sehr glatt, der Potentialgradient ist anhaltend erniedrigt, die Werte des Leitungsstromes und der Kleinionendichte sind erhöht. Kennzeichnend für Föhntyp II ist ein extrem unruhiger Verlauf der Potentialgradient- und Leitungsstromkurven bei stark erhöhten Werten an den Talstationen; er ist immer mit dem Vorkommen von Schneefegen an den Gebirgskämmen mehr oder weniger weit südlich der Registrierstationen gekoppelt. Häufig besteht bei Föhntyp II eine Bodeninversion.Für beide Föhntypen werden repräsentative Einzelbeispiele gebracht. Außerdem wurde das gesamte Beobachtungsmaterial der Jahre 1955 bis 1958 statistisch verarbeitet, um für die sieben Stationen, d. i. im Schnitt durch die Atmosphäre bis rund 3000 m NN, das luftelektrische und meteorologische Bild eines mittleren Föhntages für beide Typen abzuleiten. Die bei Föhn gesammelten Ergebnisse sind übrigens nicht nur zur Erweiterung unserer Vorstellungen über den Föhn an sich von Bedeutung, sondern geben auch Hinweise zu anderen geophysikalischen Problemen, so etwa auf dem Gebiet der Wolkenphysik (z. B. durch die Erfahrungen hinsichtlich der Ladungstrennung beim Zusammenprall und Zerbrechen von Eiskristallen), zur Frage der atmosphärischen elektrischen und elektromagnetischen Wellenvorgänge (durch Registrierungen von Stationen, die sich gerade in der Grenzschicht zwischen Föhn und positiv geladener, schwingender Inversionsoberseite befinden) sowie zur Frage des Ionisationsgleichgewichtes und der Beziehungen zwischen Kleinionen- und Kondensationskerndichte, denn in der Föhnströmung sind ja die Kondensationskerndichten besonders niedrig und außerdem ist—in den Nordalpen—die natürliche Luftradioaktivität während des Föhns erhöht.Bioklimatische Gesichtspunkte werden lediglich angedeutet.

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Summary In this paper the author summarizes data, results of evaluations, and experiences in the field of atmospheric electricity, as far as connected with foehn situations. The observations were mainly made in the region of Garmisch-Partenkirchen (Wetterstein Mountains, Northern Alps) and cover a period of five years. Seven recording stations with heights between 675 and 2963 m above sea-level were operated permanently, two further stations were operated on the Zugspitzplatt (2600 m) during two months in 1958. All the nine stations have relatively small distances from each other. At each of the nine stations the atmospheric electrical potential gradient was recorded, at four of the permanent stations and at one of the temporary stations the air-earth current was recorded, too. Further there were recorded or measured positive and negative small ions, positive and negative conductivity, natural and artificial radioactivity of the air, condensation nuclei, air pollution, point discharge current, and sferics. A characteristic of this investigation is that a dense network of stations extending also in the vertical direction yields a synopsis of a small three-dimensional portion of the atmosphere, and that uniformly without interruptions through years.It is pointed out that a foehn situation is not distinguished by a special or extraordinary behaviour of single atmospheric electrical elements, but by a typical accord of the atmospheric electrical and meteorological elements, with typical spatial variations of them within the network.From the point of view of atmospheric electricity two main types of foehn were found: Type I shows lowered and smooth potential gradient curves at all stations, further increased and smooth curves of conduction current, increased concentrations of small ions, etc. Foehn of Type II, amongst other characteristics, shows increased and extremely agitated curves of potential gradient and conduction current at the valley stations. Type II is observed when there is drifting snow at the mountain ridges south of the recording stations and mainly in cases where the foehn current does not reach the bottom of the valley.Both types are illustrated here by examples. Beyond this, the data obtained at the seven permanent stations during four years were reduced to average foehn days of both types. The observations made during foehn, however, have interest not only for our knowledge of this weather situation itself but give results which are also important for studies on cloud physics (experience on charge separations caused by breaking and impact in drifting snow), on atmospheric electric and electromagnetic waves (records of stations just being in the boundary layer between foehn current and positively charged upper surface of an inversion), for the investigation of the ionization equilibrium and of the relations between the concentrations of small ions and condensation nuclei (there are special conditions because of the low concentrations of condensation nuclei in the foehn current and because of the increased natural radioactivity of air during foehn in our region), etc.Bioclimatological points of view are mentioned, only.

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Résumé La présente étude groupe les résultats obtenus depuis cinq ans au sujet de l'aspect électrique du foehn grâce à des mesures faites dans la région du Wetterstein près de Garmisch-Partenkirchen où se trouvait un réseau de 7 stations fixes ainsi que 2 stations installées pendant une excursion de deux mois au Zugspitzplatt (2600 m.). Ces 9 postes étaient répartis entre 675 et 2693 m. et se trouvaient peu éloignés les uns des autres; tous enregistraient le gradient de potentiel, 5 le courant de conductibilité en sus. En outre on enregistrait ou mesurait: les petits ions positifs et négatifs, la conductibilité positive et négative, la radioactivité naturelle et artificielle de l'air, les noyaux de condensation, la pollution et les parasites. Le principe de base est l'utilisation des données du point de vue synoptique. L'uniformité des méthodes et leur application à longue échéance donne du poids aux résultats.On constate que les situations de foehn ne se distinguent pas par des valeurs extraordinaires des différentes grandeurs de l'électricité de l'air. Les éléments électriques et météorologiques présentent entre eux, par foehn, un accord caractéristique, tandis qu'à l'intérieur du réseau il y a des variations typiques. On peut distinguer deux types de foehn. Type I avec courbe lisse du gradient de potentiel et du courant de conductibilité; le gradient de potentiel est anormalement faible, le courant de conductibilité est accru ainsi que la densité des petits ions. Type II avec marche très agitée du gradient de potentiel et du courant (valeurs accrues aux stations basses); le foehn de type II est toujours accompagné de chasse-neige sur les crêtes au Sud; il y a souvent inversion au sol.Exemples des deux types de foehn. En outre tout le matériel d'observation des années 1955 à 1958 a été traité de façon à obtenir une image de l'état moyen de l'atmosphère jusqu'à 3000 m. pour les deux types. Les résultats trouvent également leur application à d'autres problèmes tels que la rupture de charge par heurts et bris de cristaux, les phénomènes concernant les ondes électromagnétiques, l'équilibre d'ionisation, la relation entre les petits ions et la densité des noyaux de condensation. Les points de vue biologiques ne sont qu'esquissés.

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The research reported in this document has been sponsored in part by the Geophysics Research Directorate of the Air Force Cambridge Research Center, Air Research and Development Command, United States Air Force, under Contract AF 61 (514)-732-C, AF 61 (514)-949 and AF 61 (052)-55, through the European Office, ARDC.Die Auswertungen der Schönwetter-Registrierungen wurden durch Sachbeihilfen seitens der Deutschen Forschungsgemeinschaft möglich gemacht.Die Luftradioaktivitätsmessungen wurden aus Zuschüssen des Bundesministeriums für Atomkernenergie und Wasserwirtschaft an das Institut für Gesteinskunde der Universität München bestritten.  相似文献