Analysis of a giant lightning storm on Saturn     

G. Fischer  W.S. Kurth  M.L. Kaiser  A. Lecacheux  D.A. Gurnett 《Icarus》2007,190(2):528-544

On January 23, 2006, the Cassini/RPWS (Radio and Plasma Wave Science) instrument detected a massive outbreak of SEDs (Saturn Electrostatic Discharges). The following SED storm lasted for about one month and consisted of 71 consecutive episodes. It exceeded all other previous SED observations by Cassini as well as by the Voyagers with regard to number and rate of detected events. At the same time astronomers at the Earth as well as Cassini/ISS (Imaging Science Subsystem) detected a distinctive bright atmospheric cloud feature at a latitude of 35° South, strongly confirming the current interpretation of SEDs being the radio signatures of lightning flashes in Saturn's atmosphere. In this paper we will analyze the main physical properties of this SED storm and of a single small SED storm from 2005. The giant SED storm of 2006 had maximum burst rates of 1 SED every 2 s, its episodes lasted for 5.5 h on average, and the episode's periodicity of about 10.66 h exactly matched the period of the ISS observed cloud feature. Using the low frequency cutoff of SED episodes we determined an ionospheric electron density around ¹⁰⁴ cm⁻³ for the dawn side of Saturn.  相似文献   

Retrieval of land surface temperature and emissivity from satellite data: Physics, theoretical limitations and current methods     

Prasanjit Dash  Frank-M Göttsche  Folke-S Olesen  Herbert Fischer 《Journal of the Indian Society of Remote Sensing》2001,29(1-2):23-30

Remote sensing from satellites is the only means to obtain land surface temperature (LST) and emissivity on a larger scale. LST has many applications, e.g., in radiation budget experiments and global warming, and desertification studies. Over the last decades, substantial amount of research was dedicated towards extracting LST and emissivity from surface-leaving radiance and de-coupling the two from each other. This paper provides the physical basis, discusses theoretical limitations, and gives an overview of the current methods for space-borne passive sensors operating in the infrared range, e.g., NOAA-AVHRR, Meteosat, ERS-ATSR, TERRA-MODIS, and TERRA-ASTER. Atmospheric effects on estimated LST are described and atmospheric-correction using a radiative transfer model (RTM) is explained. The methods discussed are the single channel method, the split window techniques (SWTs), and the multi-angle method.  相似文献   

Lowermost mantle anisotropy beneath the Pacific: Imaging the source of the Hawaiian plume     

Matthew J. Fouch  Karen M. Fischer  Michael E. Wysession 《Earth and Planetary Science Letters》2001,190(3-4):167-180

We utilized recordings of seismic shear phases provided by several North American broadband seismometer arrays to provide unique constraints on shear wave anisotropy beneath the northern and central Pacific Ocean. Using a new analysis method that reduces measurement errors and enables the analysis of a larger number of available waveforms, we examined relative travel times of teleseismic S and Sdiff that sample a large area of lowermost mantle structure. The results of this study provide evidence for small-scale lateral and depth variations in shear wave anisotropy for a broad region of the lowermost mantle beneath the Pacific Ocean. In particular, we image a localized zone of anomalously strong anisotropy whose strength increases toward the top of D″ beneath Hawaii. Our results, combined with a previous study of V_P/V_SH ratios, indicate that ancient subducted slab material may be responsible for observations beneath the northern Pacific, while lenses or layers of core–mantle boundary reaction products or partial melt, oriented by horizontal inflow of mantle material to the Hawaiian plume source, can explain observations beneath the central Pacific.  相似文献   

Combined analysis and test of earthquake-resistant circuit breakers     

Edward G. Fischer  William M. Daube 《地震工程与结构动力学》1976,4(3):231-244

Following the severe earthquake damage at San Fernando in 1971, it became of technical and perhaps psychological importance to demonstrate that properly re-designed electrical equipment is able to withstand even worse transient vibration phenomena which can be produced in an earthquake simulator laboratory. This has been accomplished for one column of a 500 kV gas circuit breaker and the test results are used to qualify the much larger original 3-column assembly by means of a computer-aided structural analysis. Since the equipment exhibited some closely spaced, cross-coupled modes of vibration, a valuable comparison could be obtained between the effects produced by El Centro 1940 ground acceleration and those for a more purposeful sine beat vibration input. The latter can be adjusted to produce definite stresses and fatigue effects in specific parts of the equipment due to quasi-resonance response.  相似文献   

Book reviews     

Gaston Fischer  E. Klingelé  P. D. Phillips 《Pure and Applied Geophysics》1980,119(4):888-892

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Quasitrapped protons (E p =1–11 MeV) nearL=4 registered by intercosmos-13 satellite     

Ivan Kimák  Karel Kudela  P. V. Vakulov  Reviewer S. Fischer 《Studia Geophysica et Geodaetica》1982,26(2):207-211

Summary Data obtained from apparatus detecting energetic particles on low altitude polar orbiting satellite Intercosmos-13 show enhancement of quiasitrapped proton flux (E_p=1–11 MeV) near L=4 in comparison with both and lower L. This phenomenon persists during intervals with low level of geomagnetic activity. Possibility of influence of false pulses on the result is discussed.  相似文献   

Ion whistlers in mid-latitude trough of light ions     

Jaroslava Bošková  František Jiříček  Reviewer S. Fischer 《Studia Geophysica et Geodaetica》1982,26(3):295-299

Summary In the set of VLF data from the Interkosmos-14 satellite (launched on 11 December 1975 with apogee height of 1707 km, perigee 345 km and inclination 74°) as received in direct telemetry transmissions at the Observatory Panská Ves (Czechoslovakia), ion cyclotron whistlers were found at unusually high geomagnetic latitudes. These whistlers indicate a marked decrease of proton density in the close vicinity of the satellite with increasing geomagnetic latitude. It appeared, moreover, that proton whistlers at higher geomagnetic latitudes even sensitively reflected the rapid changes of plasma parameters within the region of the mid-latitude trough of light ions.  相似文献   

Airborne microorganisms: Their occurrence,distribution and dependence on environmental factors — Especially on organic compounds of air-pollution     

Priv.-Doz. Dr. med. H. Rüden  Prof. Dr. med. E. Thofern  Dr. med. P. Fischer  Dr. Ing. U. Mihm 《Pure and Applied Geophysics》1978,116(2-3):335-350

For a period of approximately six months the concentrations of airborne microorganisms were determined by the uptake of their day-characteristic at local places differing by the extent of air pollution. By simultaneously recording the meteorological parameters as temperature, relative humidity, direction and velocity of wind and intensity of solar radiation, it was intended to find out the relationship between these factors and the viability of airborne microorganisms. The present data show an oscillation of the concentration counts over a wide range and seem not yet to depend on the local situation of air pollution.In a further series of experiments the atmospheric aerosol <10 m was collected on air-filters. The decreased substances were extracted from the filter material by aqueous and organic solutants and tested for their antimicrobial activities. In this context the seasonal dependence of the microbicidal activity of organic compounds of aerosol is discussed.  相似文献   

Geometrische und elektrostatische Berechnungen am Quarz- und am Cristobalit-Typ. I. Modelle mit AB4-Tetraedern der Symmetrie\bar 43m     

Dr. R. Fischer  Prof. Dr. J. Zemann 《Mineralogy and Petrology》1975,22(1):1-14

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Beobachtungen zur Phänologie eines Alpentales     

Burkhard Frenzel  Hermann Fischer 《Theoretical and Applied Climatology》1957,8(2):231-256

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