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

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.     

The GRECOS operating system of the GCT

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.     

Combined influence of PDO and ENSO on northern Andean glaciers: a case study on the Cotopaxi ice-covered volcano,Ecuador

This paper describes the application of remote sensing in monitoring the fluctuations in one of the mountain glaciers in the Ecuadorean Andes during the past few decades using ASTER, EO-1 ALI, Landsat MSS, TM and ETM + images. Satellite images were used to calculate the snow line altitudes (SLAs) during the period 1979–2013. Cotopaxi ice covered volcano was studied as representative of Ecuadorian glaciers in the eastern cordillera. Precipitation and air temperature data from various gauging stations within the range of 30 km from the study site and monthly discharge and water level data from a gauging station were also utilized in this study. Anomalies in precipitation and temperature were found to be slightly different in the Cotopaxi region compared to nearby Antizana in the same cordillera and Chimborazo region in the western cordillera. An attempt to correlate the El Niño—southern oscillation phenomenon with the glacier fluctuations in Ecuadorian Andes was done successfully. Cold and warm regimes of Pacific Decadal Oscillation is also considered. The calculated glacier fluctuations obtained were similar to that performed on the nearby Antizana 15 in the eastern cordillera during 1995–2002. Precipitation and temperature anomalies were similar with Antizana 15. It is evident from the research that SLAs were highly fluctuated between the period of occurrence of El Niño and La Niña events. It is also seen that the glacier fluctuations show a negative mass balance trend in during the warm regime of Pacific Decadal Oscillation during the past three decades. Glaciated areas were advanced during the La Nina events in the cold regime of PDO during 1998–2002.     

Catchment precipitation processes in the San Francisco valley in southern Ecuador: combined approach using high-resolution radar images and in situ observations

The precise estimation of precipitation quantities in tropical mountain regions is in great demand by ecological and hydrological studies, due to the heterogeneity of the rainfall distribution and the lack of meteorological station data. This study uses radar images and ground station data to provide the required high-resolution precipitation maps. Also wind data are taken into account, due to its influence on the precipitation formation and to demonstrate the relation between synoptic wind, topography and the precipitation distribution inside small mountain valleys. The study analyses the rainfall distribution and amounts of 4 days inside the San Francisco Valley, a small catchment in the tropical Andes of southern Ecuador, representing different seasons and the typical atmospheric flows, which are correlated to the annual precipitation map. The results show that the rainfall distribution and amounts are generally defined by the wind direction and velocity, besides the topographic location in relation to the main barriers and pathways. The dominant wind direction causes a division of the catchment in a wetter eastern and a dryer western part. Moreover, the annual seasons are reversed; the main rainy season for the eastern part occurs between June and August, while the western part reaches the precipitation maximum between January and March. This may have influence on the species composition at the different slopes and the annual hydrological cycle inside the catchment.     

The Glueckstadt Graben of the North-German Basin: new insights into the structure from 3D and 2D gravity analyses

The structure of the Glueckstadt Graben has been investigated by use of 3D gravity backstripping technique and by 2D gravity and magnetic modelling. Subtracting the gravity effects of the Meso-Cenozoic sediments together with Permian salt reveals a positive residual anomaly within the Glueckstadt Graben. This anomaly includes two local maxima over the Westholstein and Eastholstein Troughs. The 2D gravity models point to the presence of a high-density body within the lower crust of the Glueckstadt Graben. In addition, the results of 2D magnetic modelling indicate that the central part of the high-density body is overlain by an area with high susceptibility. Most probable, the formation of this high-density body is a result of complex poly-phase tectonic history of the study area. Finally, the results of gravity modelling indicate that Permian salt is not homogeneous. 3D gravity analysis and, especially, 2D gravity modelling have distinguished the differences in degree of salt saturation in salt-rich bodies, and elucidate the proportion of Rotliegend salt.     

Strain localization due to structural in-homogeneities in the Central European Basin System

The large-scale crustal deformations observed in the Central European Basin System (CEBS) are the result of the interplay between several controlling factors, among which lateral rheological heterogeneities play a key role. We present a finite-element integral thin sheet model of stress and strain distribution within the CEBS. Unlike many previous models, this study is based on thermo-mechanical data to quantify the impact of lateral contrasts on the tectonic deformation. Elasto-plastic material behaviour is used for both the mantle and the crust, and the effects of the sedimentary fill are also investigated. The consistency of model results is ensured through comparisons with observed data. The results resemble the present-day dynamics and kinematics when: (1) a weak granite-like lower crust below the Elbe Fault System is modelled in contrast to a stronger lower crust in the area extending north of the Elbe Line throughout the Baltic region; and (2) a transition domain in the upper mantle is considered between the shallow mantle of the Variscan domain and the deep mantle beneath the East European Craton (EEC), extending from the Elbe Line in the south till the Tornquist Zone. The strain localizations observed along these structural contrasts strongly enhance the dominant role played by large structural domains in stiffening the propagation of tectonic deformation and in controlling the basin formation and the evolution in the CEBS.     

Synoptisch-luftelektrische Daueruntersuchungen im Hochgebirge im Dienste der Meteorologie

Zusammenfassung Zur Erforschung von Beziehungen zwischen luftelektrischen Phänomenen in verschiedenen Höhenstufen und zahlreichen meteorologischen Vorgängen wurden seit einigen Jahren im Alpenbereich Dauerregistrierungen des statischen luftelektrischen Feldes ausgeführt. Es dienten hierzu das StationspaarOberstdorf (815 m) undNebelhorn (1930 m) im Allgäu sowie die StationenGarmisch-Partenkirchen (705 m),Eibsee (1000 m),Riffelriss (1640 m) undZugspitze (2963 m) im Wetter-steingebirge. — Anhand von typischen Kurvenbeispielen werden folgende Beziehungen besprochen: 1)Untersuchungen von Lokaleffekten an den Tal- Hang- und Gipfelstationen, ausgelöst durch:a) verschiedene Aerosole (Staub, Rauch, Dunst, Nebel usw.);b) orographisch bedingte Windsysteme (Berg-Talwind, Hangwind);c) Föhnerscheinungen. — 2)Synoptisch-Luftelektrische Beobachtungen, und zwar:a) Verhalten des luftelektrischen Feldes über und unter Inversionsschichten, Dunstgrenzen und Konvektionsgrenzen zum Studium des Verhaltens der Grundschicht (Schneider-Carius);b) Erforschung der vertikalen Ladungsverteilung in stratiformer Bewölkung (Untersuchungen über polarisierte Wolkenschichten);c) Erforschung der vertikalen Ladungsverteilung in Turbulenzbewölkung zum Studium des elektrischen Aufbaus von Schauer- und Gewitterwolken unter Berücksichtigung ihrer zeitlichen Entwicklung;d) Studien über den vertikalen Luftmassenaustausch;e) Studien über das Verhalten des luftelektrischen Feldes bei Niederschlägen verschiedener Art insbesondere bei Phasenwechsel.

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Summary In order to investigate the relations between atmospheric electric phenomena in different altitudes and various meteorological processes, continuous automatical recordings of the statical atmospheric potential gradient have been performed in the alpine region since several years. — Two stations in the Allgäu Mountains:Oberstdorf (815 m) andNebelhorn (1930 m) and four stations in the Wetterstein Mountains:Garmisch-Partenkirchen (705 m),Eibsee (1000 m),Riffelriss (1640 m) andZugspitze (2963 m) serve to this purpose. — Using typical curves, we demonstrate the results of the study of the following problems: 1) Local effects at both valley stations and mountain stations, caused bya) various aerosols (dust, smoke, vapour, fog, etc.),b) winds, conditioned by orographical circumstances,c) foehn; 2) Synoptical problems of the atmospheric electricity:a) the behaviour of the atmospheric potential gradient both above and below inversions and superior limits of convection in order to study the status of the fundamental layer of the atmosphere («Grundschicht»,Schneider-Carius),b) the vertical variation of the electric charge in sheet clouds (polarisations of sheet clouds),c) the vertical variation of electric charge in shower and thunderstorm clouds in order to study their electric structure and chronologic development.d) vertical exchange of air masses,e) the behaviour of the atmospheric potential gra- dient during various forms of precipitation, especially if there is a change of the phase.

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Vortrag gehalten auf der 3. Internationalen Tagung für Alpine Meteorologie in Davos, April 1954.