Funkpeilungen des ersten künstlichen Erdsatelliten Sputnik

Zusammenfassung Die am 16. und 17. Oktober 1957 auf der Frequenz 20,005 MHz durchgeführten Funkpeilungen nach dem ersten künstlichen Erdsatelliten Sputnik werden mitgeteilt. Dabei ist insbesondere bei den mit dem Doppelkanal-Sichtfunkpeiler erhaltenen photographisch registrierten Ergebnissen charakteristisch, daß reine Strichpeilungen erhalten wurden. Bei den verschiedenen Beobachtungsserien wurden sowohl Linksauswanderungen als auch Rechtsaus-wanderungen der Peilungen über Winkelbereiche zwischen etwa 4° und 171° beobachtet. Diesen Peilungen nach einem außerhalb der Ionosphäre befindlichen Kurzwellensender wurden Peilungen nach zwei auf annähernd gleicher Frequenz wie der Satellit sendenden Funkstationen in sehr großer Entfernung, die beide die für kohärente Wellen charakteristische elliptische Aufspaltung zeigen, gegenübergestellt.

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Radio bearings taken from the first artificial satellite of the earth, Sputnik

Summary Information is given about the radio bearings taken from the first satellite Sputnik on 16th and 17th October 1957 on a frequency of 20,005 Mc. A special feature is that the results obtained by application of the twinchannel visual direction finder are pure line indications. The different series of observations show a variation of the bearings in a clockwise direction as well as in an anticlockwise direction, covering angles between circ. 4° and 171°. These bearings for a shortwave transmitter beyond the ionosphere were compared with bearings for two very distant stations on nearly identical frequencies which both show the elliptical split being characteristic of coherent waves.

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Relèvements pris pour le premier satellite artificiel de la terre, Sputnik

Résumé Le rapport présent a pour objet les relèvements pour le premier satellite de la terre Sputnik pris sur la fréquence de 20,005 Mc/s le 16 et le 17 octobre 1957. Les résultats obtenus à l'aide du radiogoniomètre visuel à deux canaux et au moyen des enregistrements photographiques se caractérisent par le fait que les relèvements apparaissent toujours en forme de trace. Au cours des différentes séries d'observations les relèvements étaient soumis à des variations vers la droite et vers la gauche couvrant des angles de 4° à 171° environ. Ces relèvements pour un émetteur à ondes courtes qui se trouve en dehors de la ionosphère ont été comparés à ceux de deux stations-radio à très grande distance qui travaillent à peu près sur la même fréquence que le satellite lui-même. Les relèvements pour ces deux stations se présentent en forme d'ellipse, trait caractéristique de la réception d'ondes cohérentes.

     

Funkeigenpeilung,ihre Vorteile und ihre Grenzen

Zusammenfassung Die vom Nautiker grundsätzlich bevorzugte Eigenpeilung erhält bei Einsatz des Sichtfunkpeilers an Bord erweiterte Anwendungsmöglichkeiten (größere Reichweiten, Peilmöglichkeit bei Störsendern und starken atmosphärischen Störungen, kompaßunabhängige Zielfahrt und Standortsbestimmung). Für die Erzielung größter Reichweiten und für Dämmerungs- und Nachtpeilungen ist man beim heutigen Stand der Technik noch auf Fremdpeilungen mit Adcockpeilern angewiesen. Im Grenzwellenbereich können optimale Peilergebnisse auch nur durch Fremdpeilungen mit Adcockpeilern erzielt werden. Für die Aufgaben, bei denen auf Eigenpeilungen im Grenzwellengebiet nicht verzichtet werden kann, ist die Verwendung von Sichtfunkpeilern von besonderem Vorteil.

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Radio sell-bearings, their advantages and limitations

Summary The applicability of self-bearings (which are, on principle, preferred by navigators) is greatly extended by using the Visual Direction Finder on board ships (longer ranges; possibility to take bearings even in the presence of interfering transmitters and atmospherics; possibility of homing and position finding independent of the compass). For obtaining maximum ranges and for taking bearings during the dark and twilight hours, it is still necessary at the present state of technics, to take bearings from the ground by means of Adcock systems. Also in the wave band between 100 and 200 m (coastal band), optimum results can be obtained only with the aid of ground bearings by means of Adcock direction finders. For such problems which require self-bearings in the coastal band, it is of particular advantage to employ Visual Direction Finders.

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Radiogoniométrie de bord — Avantages et limites

Résumé Les navigateurs préfèrent en général la radiogoniométrie de bord à la goniométrie au sol. Un goniomètre cathodique offre des possibilités tout à fait nouvelles à la goniométrie de bord, c. à. d. portées plus étendues — radio-goniométrie même en présence d'émetteurs perturbateurs ou de parasites atmosphériques — navigation vers un but indépendamment du compas — détermination du point de navire. A l'état actuel de la technique on est encore obligé d'employer la radiogoniométrie au sol au moyen d'appareils Adcock pour obtenir les plus grandes portées possibles et pour la goniométrie nocturne. En outre, ce n'est qu'en se servant de la radiogoniométrie Adcock au sol qu'on a dans la gamme d'ondes minima des portées maxima. Dans les cas où on ne peut pas renoncer dans la gamme des ondes minima à la radiogoniométrie de bord l'emploi du goniomètre cathodique est particulièrement avantageux.

     

Sensitivity of boreal forests to possible climatic warming

General circulation models indicate substantial CO₂ warming in high latitudes. In these regions, which include the boreal coniferous forests, the activity of ecosystems is largely controlled by temperature. The effective temperature sum (degree-days) is used in this study for describing the regional variability in the productivity of boreal ecosystems. Although the concept is simple, it takes into account two basic factors: the length of the growing season and the day-to-day level of activity of the ecosystem. This study examines which areas in the boreal coniferous forests would be most sensitive to a possible climatic warming. The data used in the study are for Finland.A regression is estimated between regional forest growth rate and effective temperature sum. A climatic warming is assumed and the corresponding growth response is calculated, using the regression, for northern and southern areas, and for maritime and continental areas. The response is expressed in terms of (i) absolute increase in growth (grams per m² per year) and (ii) relative increase in growth. The results indicate that a given climatic warming would yield the greatest absolute increase in growth in warm (i.e. southern) and maritime parts of the biome. In terms of the relative growth response the sensitivity would increase northward and toward maritime areas.     

Climate change,the monsoon,and rice yield in India

Recent research indicates that monsoon rainfall became less frequent but more intense in India during the latter half of the Twentieth Century, thus increasing the risk of drought and flood damage to the country’s wet-season (kharif) rice crop. Our statistical analysis of state-level Indian data confirms that drought and extreme rainfall negatively affected rice yield (harvest per hectare) in predominantly rainfed areas during 1966–2002, with drought having a much greater impact than extreme rainfall. Using Monte Carlo simulation, we find that yield would have been 1.7% higher on average if monsoon characteristics, especially drought frequency, had not changed since 1960. Yield would have received an additional boost of nearly 4% if two other meteorological changes (warmer nights and lower rainfall at the end of the growing season) had not occurred. In combination, these changes would have increased cumulative harvest during 1966–2002 by an amount equivalent to about a fifth of the increase caused by improvements in farming technology. Climate change has evidently already negatively affected India’s hundreds of millions of rice producers and consumers.     

Observation of snowfall with a low-power FM-CW K-band radar (Micro Rain Radar)

Quantifying snowfall intensity especially under arctic conditions is a challenge because wind and snow drift deteriorate estimates obtained from both ground-based gauges and disdrometers. Ground-based remote sensing with active instruments might be a solution because they can measure well above drifting snow and do not suffer from flow distortions by the instrument. Clear disadvantages are, however, the dependency of e.g. radar returns on snow habit which might lead to similar large uncertainties. Moreover, high sensitivity radars are still far too costly to operate in a network and under harsh conditions. In this paper we compare returns from a low-cost, low-power vertically pointing FM-CW radar (Micro Rain Radar, MRR) operating at 24.1?GHz with returns from a 35.5?GHz cloud radar (MIRA36) for dry snowfall during a 6-month observation period at an Alpine station (Environmental Research Station Schneefernerhaus, UFS) at 2,650?m height above sea level. The goal was to quantify the potential and limitations of the MRR in relation to what is achievable by a cloud radar. The operational MRR procedures to derive standard radar variables like effective reflectivity factor (Z _e) or the mean Doppler velocity (W) had to be modified for snowfall since the MRR was originally designed for rain observations. Since the radar returns from snowfall are weaker than from comparable rainfall, the behavior of the MRR close to its detection threshold has been analyzed and a method is proposed to quantify the noise level of the MRR based on clear sky observations. By converting the resulting MRR-Z _e into 35.5?GHz equivalent Z _e values, a remaining difference below 1?dBz with slightly higher values close to the noise threshold could be obtained. Due to the much higher sensitivity of MIRA36, the transition of the MRR from the true signal to noise can be observed, which agrees well with the independent clear sky noise estimate. The mean Doppler velocity differences between both radars are below 0.3?ms^?1. The distribution of Z _e values from MIRA36 are finally used to estimate the uncertainty of retrieved snowfall and snow accumulation with the MRR. At UFS low snowfall rates missed by the MRR are negligible when comparing snow accumulation, which were mainly caused by intensities between 0.1 and 0.8 mm?h^?1. The MRR overestimates the total snow accumulation by about 7%. This error is much smaller than the error caused by uncertain Z _e?Csnowfall rate relations, which would affect the MIRA36 estimated to a similar degree.     

Risk-based characterisation of an urban building site

The evaluation of the underground soil stratigraphy is a key aspect in geotechnical site characterisation. However, these means of site exploration are only pinholing subsoil conditions and expert knowledge is needed to understand subsoil conditions in order to build a reliable geological-geotechnical model. This contribution employs a geostatistical simulation methodology for the simulation of random fields representing geological uncertainty. This combines borehole data and expert knowledge via a mathematical framework. Moreover a risk-based site characterisation scheme is developed for urban site characterisation. This novel characterisation scheme offers additional insight into the effects of large-scale, geological spatial variability by using fragility curves to quantify these effects.     

Integrated scenarios of acidification and climate change in Asia and Europe

Two integrated assessment models, one for climate change on a global scale (IMAGE 2) and another for the regional analysis of the impacts of acidifying deposition (RAINS), have been linked to assess the impacts of reducing sulphur emission on ecosystems in Asia and Europe. While such reductions have the beneficial effect of reducing the deposition of acidifying compounds and thus the exceedance of critical loads of ecosystems, they also reduce the global level of sulphate aerosols and thus enhance the impact of increased emissions of greenhouse gases, and consequently increase the risk of potential vegetation changes. The calculations indicate that about 70% of the ecosystems in Asia would be affected by either acid deposition or climate change in the year 2100 (up from 20% in 1990) for both sulphur emission scenarios (controlled and uncontrolled), whereas in Europe the impacted area would remain at a level of about 50%, with a dip early next century. More generally, the effects of reducing sulphur emissions and thus enhancing climate change would about balance for the Asian region, whereas for Europe the desirable impact of sulphur emission reductions would greatly outweigh its undesirable effects.     

Inter‐ and intra‐colonial genotypic diversity in hermatypic hydrozoans of the family Milleporidae

Genetic diversity is the basis for adaptation and therefore of primary scientific interest, especially in species that are threatened by anthropogenic challenges, e.g. climate change and/or pollution. Coral reefs are among the most threatened but also the most diverse ecosystems and have therefore been studied quite extensively. So far, most investigations have focused on scleractinian corals while the equally important reef builders, the hydrozoans, have been less considered. Here we provide the first study of genotypic variability as well as intra‐colonial genetic variability, the co‐occurrence of more than one genotype within a single colony, in Milleporidae based on microsatellites. We analysed two geographically distinct populations from the Millepora dichotoma complex, one from the Red Sea and one from the Great Barrier Reef. Additionally, a population of Millepora platyphylla was analysed from French Polynesia. We compared microsatellite multilocus genotypes and cytochrome c oxidase subunit I haplotypes for each of the three field sites to detect levels of genotypic diversity at the intra‐ and inter‐specific levels. Furthermore, we examined all species for the occurrence of intra‐colonial genetic variability, a recently described mechanism in scleractinian corals that might enhance the adaptive potential of sessile organisms. We found both species and all field sites to be genotypically variable. Twelve mitochondrial haplotypes and 27 multilocus microsatellite genotypes were identified. In addition, intra‐colonial genetic variability was detected in the M. dichotoma complex from the Great Barrier Reef as well as in M. platyphylla from French Polynesia. All of the intra‐colonial genetically variable colonies consisted of one main genotype and a second divergent genotype caused by somatic mutations (mosaicism). Our study proves that Milleporidae are genetically variable and that the phenomenon of intra‐colonial genetic variability also occurs in this important reef‐building family.