Versuch einer meeresmorphologischen Deutung von Satelliten-Luftbildern

Zusammenfassung Während man schon seit einiger Zeit Satelliten-Luftbilder für Festlandsbereiche interpretierte, nahm man allgemein an, daß die Meere auf diesen Bildern von einem einheitlichen und undifferenzierten Schwarz wiedergegeben würden. Es stellte sich aber heraus, daß auf manchen Bildern im Bereich der Meere deutlich verschiedene Grautönungen zu erkennen sind, die die Vermutung aufkommen lassen, es könne hier ein primärer oder zumindest sekundärer Zusammenhang mit submarinen Strukturen bestehen und es müßten sich somit Satelliten-Luftbilder auch meeresmorphologisch auswerten lassen.Zur Prüfung dieser Möglichkeit wurden in der vorliegenden Arbeit aus einer Fülle von Aufnahmen 27 Satelliten-Luftbilder mit entsprechenden Seekarten und anderen Unterlagen verglichen. Es zeigten sich an einigen Stellen verblüffende Übereinstimmungen von gewissen Grautönungen mit bekannten submarinen Formen, während an vielen anderen Stellen zunächst nur unsichere Aussagen möglich sind. Vor allem läßt sich derzeit noch nicht entscheiden, ob und wieweit primäre oder sekundäre Zusammenhänge bestehen.Die zur Beurteilung der Satellitenbilder notwendigen technischen Angaben bezüglich des Aufnahme- und Übertragungsverfahrens werden kurz resumiert, ausführlicher wird darüber an anderen Stellen (vgl. Schrifttum) berichtet.Eine kritische Diskussion des Problems der Eindringtiefe von Licht in Wasser führte zu der Annahme, daß im Bereich des Sonnenreflexes größere Tiefen als bislang vermutet ausgeleuchtet werden und sich aus der Zusammenschau aus großer Höhe veränderte optische Bedingungen ergeben können, als wir sie gewohnt sind.Insgesamt sprechen die Ergebnisse dafür, daß die Aussagefähigkeit der Methode noch an technischen Mängeln und dergleichen leidet, im Prinzip aber doch neue Beiträge zur Ozeanographie erwarten läßt.

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Essay of an ocean-morphological interpretation of Satellite-air-Pictures

Summary While for some time, Satellite-air-Pictures have already been interpreted for evaluation in the continental sphere, it was generally assumed that the oceans in such pictures were shown in an uniform and undifferentiated black colour. However, it was concluded that on some of these photos, showing the oceans, greyish shades were clearly visible which fact led to the assumption that one is confronted here primarily or, at least, secondarily by a coherence with submarine structures and, therefore, Satellite-air-Photos could perhaps also be construed in an ocean-morphological way.In order to test such a possibility, 27 Satellite-air-Photos out of a lot of pictures have been compared with the respective sea-charts and other data. In some instances, amazing conformities of certain greyish hues with the known substratal forms got visible, while in many other spots, so far, only vague statements can be made. First of all, at this point, it cannot as yet be decided whether and how far a primary or secondary context exists.The necessary technical data for the evaluation of such Satellite-air-Photos, with reference to the receiving and transmitting procedures, will be summarized in short, yet reports in greater detail can be found in the comparable literature.A critical discussion of the problems of depth of light-penetration into the water led us to the assumption that in the sphere of sunreflexes greater depths than so far presumed can be reached and, by the synoptical view from enormous heights, completely changed optical conditions may result, than we are so far used until now.Altogether, the results prove that the capacity of this method is still suffering from technical shortcomings, principally however, new contributions to oceanography can be expected.

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Essai d'une exploitation des images par satellites pour la morphologie marine

Résumé Tandis que depuis quelque temps déjà on interprétait des images par satellites de zones continentales, il était admis en général que les mers, sur ces images, seraient rendues par un «noir» uniforme sans nuances. Mais en fait, sur plus d'une image, on peut reconnaître distinctement dans les zones maritimes diverses tonalités de gris qui donnent à penser qu'il pourrait y avoir là une relation de premier ou tout au moins de second ordre avec des structures sous-marines. Dans ces conditions des images par satellites devraient offrir un intérêt pour la morphologie marine.Afin de vérifier cette possibilité, dans la présente étude, on a comparé 27 images par satellites, tirées d'un grand nombre de prises de vues, avec les cartes marines correspondantes et d'autres documents. En quelques points apparuent des concordances surprenantes entre certains tons de gris et des formes sous-marines connues, tandis qu'en beaucoup d'autres endroits on ne peut encore rien préciser pour le moment. Avant tout, en l'état actuel des choses, on ne peut encore affirmer qu'il existe — et dans quelle mesure — des concordances d'ordre primaire ou secondaire.Les données techniques nécessaires pour l'appréciation des images par satellites en ce qui concerne les procédés de prises de vue et de transmission, sont résumées succinctement; elles sont traitées de façon plus détaillée ailleurs (voir bibliographie).Une discussion critique du problème de la profondeur de pénétration de la lumière dans l'eau, permet de supposer que dans la zone où pénètre la lumière solaire, des profondeurs plus grandes que celles admises jusqu'alors sont éclairées et aussi que de la «vue d'ensemble», de haute altitude, peuvent résulter des conditions optiques qui diffèrent de celles auxquelles nous sommes accoutumés.Dans l'ensemble les résultats montrent que les informations à attendre de la méthode, souffrent encore d'un insuffisance de moyens techniques et autres mais laisse entrevoir, en principe, de nouvelles contributions à l'océanographie.

     

High-Resolution Infrared Imaging of Neptune from the Keck Telescope

We present results of infrared observations of Neptune from the 10-m W. M. Keck I Telescope, using both high-resolution (0.04 arcsecond) broadband speckle imaging and conventional imaging with narrowband filters (0.6 arcsec resolution). The speckle data enable us to track the size and shape of infrared-bright features (“storms”) as they move across the disk and to determine rotation periods for latitudes −30 and −45°. The narrowband data are input to a model that allows us to make estimates of Neptune's stratospheric haze abundance and the size of storm features. We find a haze column density of ∼10⁶ cm⁻² for a haze layer located in the stratosphere, and a lower limit of 10⁷ cm⁻² and an upper limit of 10⁹ cm⁻² for a layer of 0.2 μm particles in the troposphere. We also calculate a lower limit of 7×10⁶ km² for the size of a “storm” feature observed on 13 October 1997.     

Keck Adaptive Optics Images of Uranus and Its Rings

We present adaptive optic images of Uranus obtained with the 10-m W. M. Keck II telescope in June 2000, at wavelengths between 1 and 2.4 μm. The angular resolution of the images is ∼0.06-0.09″. We identified eight small cloud features on Uranus's disk, four of which were in the northern hemisphere. The latter features are ∼1000-2000 km in extent and located in the upper troposphere, above the methane cloud, at pressures between 0.5 and 1 bar. Our data have been combined with HST data by Hammel et al. (2001, Icarus153, 229-235); the combination of Keck and HST data allowed derivation of an accurate wind velocity profile. Our images further show Uranus's entire ring system: the asymmetric ? ring, as well as the three groups of inner rings (outward from Uranus): the rings 6+5+4, α+β, and the η+γ+δ rings. We derived the equivalent I/F width and ring particle reflectivity for each group of rings. Typical particle albedos are ∼0.04-0.05, in good agreement with HST data at 0.9 μm.     

Numerical Homogenization of the Rigidity Tensor in Hooke''s Law Using the Node-Based Finite Element Method

Combining a geological model with a geomechanical model, it generally turns out that the geomechanical model is built from units that are at least a 100 times larger in volume than the units of the geological model. To counter this mismatch in scales, the geological data model's heterogeneous fine-scale Young's moduli and Poisson's ratios have to be upscaled to one equivalent homogeneous coarse-scale rigidity. This coarse-scale rigidity relates the volume-averaged displacement, strain, stress, and energy to each other, in such a way that the equilibrium equation, Hooke's law, and the energy equation preserve their fine-scale form on the coarse scale. Under the simplifying assumption of spatial periodicity of the heterogeneous fine-scale rigidity, homogenization theory can be applied. However, even then the spatial variability is generally so complex that exact solutions cannot be found. Therefore, numerical approximation methods have to be applied. Here the node-based finite element method for the displacement as primary variable has been used. Three numerical examples showing the upper bound character of this finite element method are presented.     

磁暴期间极光椭圆与极盖区电离层效应比较研究——F区负暴

联合利用EISCAT和E-Svalbard非相干散射雷达数据,研究l997年5月强磁暴期间向阳侧极盖与极光椭圆区电离层F区负暴.发现在磁暴主相和恢复相初期,极光椭圆和极盖区电离层都在大约l90km高度出现类似F1的峰,F2主峰完全消失,F区电子密度大幅度下降.但离子温度的变化在两个区域很不相同,在极光椭圆区大幅度升高,而在极盖区没有显著变化,反映出引起F区负暴的主要机制在两个区域不尽相同.强对流电场引起大气焦耳加热与离子增温而使O+离子消失的化学反应速率增大所导致的电离损失,对极光椭圆区负暴起主要作用;而输运过程,特别是持续长达数小时的沿场上行离子流,对极盖区负暴起重要作用.磁暴主相期间,当EISCAT雷达位于等离子体对流涡旋转换区下方时,在无焦耳加热与离子摩擦增温的情况下,观测到由顶部电离层O+离子沿场高速外流引起的F区电子密度耗空.     

Beef feedlots in southwestern Kansas: local change, perceptions, and the global change context

Cattle feedlots, some of which have a capacity of tens of thousands of head, have become a major driving force in the local economy and changing landscape of southwestern Kansas. The feedlot industry also is one of the region's most important sources of carbon-equivalent greenhouse gases. Changes to the beef industry are described, and the perceptions and attitudes of feedlot operators regarding climatic change issues and industrial change are analyzed based on a 1998 survey. The results indicate that a majority of feedlot respondents believe ‘global warming’ is mostly an unproven theory, and efforts to mitigate it are unwarranted.     

Setting Wildfire Evacuation Trigger Points Using Fire Spread Modeling and GIS

Warning communities in the path of an advancing wildfire is a challenging problem. Decision makers need the most current information available to determine who should evacuate, when they should leave and what type of order to issue (e.g. mandatory, recommended, voluntary). This paper presents a new method for delimiting wildfire evacuation trigger points using fire spread modeling and GIS. Using data on wind, topography, and fuel in conjunction with estimated evacuation time, a trigger buffer can be computed for a community whereby an evacuation is recommended if a fire crosses the edge of the buffer. A case study is presented for the Corral Canyon section of the 1996 Calabasas Fire near Malibu, California, USA. The paper concludes with a discussion of the strengths and weaknesses of this approach.     

Case 23 nomination of precursory seismic quiescence as a significant precursor

Conclusions Several cases of extremely strong quiescences have been investigated in great detail, and it was found that they are statistically highly significant and that they cannot be reasonably explained by catalog heterogeneity. Several additional cases of quantitatively measured quiescence have been documented. The method of measuring quiescence has progressed from using visual means to using a quantitative approach, and the understanding of the noise sources has significantly advanced during the last few years. Therefore I feel that quiescence is a real phenomenon and the method to detect it has matured to a point that is acceptable for the List of Significant Precursors, although considerably more work needs to be done to understand this parameter and its role in the earthquake generation process.     

The seasonal productivity cycle of phytoplankton and controlling factors in Lake Constance

Annual phytoplankton productivity in Lake Constance is about 300 g C m⁻², a value typical for mesoeutrophic lakes. Seasonal variations in phytoplankton biomass and productivity are exceptionally great because of a sequence of factors controlling the production process. During winter productivity is controlled by low energy inputs and high respiratory losses due to deep water column mixing. Biomass is low and water transparancy high. The spring phytoplankton growth is triggered by the thermal stabilization of the water column. The summer phytoplankton biomass maximum mainly depends on phosphorus availability. However, biomass yields comprise only 15–20% of values to be expected from the Redfield ratio because large proportions of POM are detritus and non-algal biota. Moreover, sedimentation during the second half of the year removes biomass from the euphotic zone. Water transparency and thus vertical distribution of algal photosynthesis is highly dependent on phytoplankton biomass. Self-shading causes considerably smaller seasonal variations in areal biomass and photosynthetic rates than in volume-based values. By light-shade adaptation effects of seasonal fluctuations in mean daily surface radiance fluxes on algal photosynthesis can to a significant extent be compensated for. At any given level of biomass daylength is the major determinant of daily production rates. Dedicated to Professor Elster on his 80th birthday.