Dichte und Lichtbrechung der Moldavite von Něchov

In this experimental work I studied the correlation of the specific gravity and index of refraction at 19 moldavites from a finding place in Nchov. This place is in the south of Bohemia, in a district of eské Budjovice (Budweis). The reason for this work was the extraordinary declaration of the correlation of the specific gravity and index of refraction at one moldavite from Nchov that is: d=2,395 and n _D =1,5033.These declarations were settled by Nováek. The results of these measurings have shown that the linear correlation of the specific gravity and index of refraction of the moldavites from other finding places are characteristic also for these ones. The definition of this correlation at 19 pieces of moldavites from Nchov shows also this linear character in the measuring of values d=2,355–2,395 and n _D =1,4870–1,4950.In this work there were settled also some other dates of unity (so-called in couple-moldavites). But we must not oversee certain vaccilations of the declaration at the moldavites from Nchov, as at those from other finding places. The secularity of these declarations about the moldavites of Nchov lies also therein, that the avarage value of the correlation of specific gravity and index of refraction of this finding place is higher than those of other places.

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Herrn Dr. Walter Weiskirchner, Dozent an der Universität Tübingen, danke ich herzlich für die freundliche Durchsicht der Arbeit.     

Kontinuierliche Messungen von Atmosphärischen Kondensationskernen

Ohne Zusammenfassung     

Erfahrungen mit dem automatischen Kondensationskernzähler

Zusammenfassung Es wird über Erfahrungen mit einem früher an dieser Stelle beschriebenen automatischen Kondensationskernzähler berichtet und speziell die Abhängigkeit der gemessenen Kernzahl von Expansionsgrad, Temperatur und relativer Feuchtigkeit untersucht, sowie die Einstellung einer konstanten Empfindlichkeit beschrieben.

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Summary Experiments are reported with the automatic condensation nuclei counter, which has already been described in this review. Adjustment for a constant sensitivity is described. The dependence of the number of nuclei upon the degree of expansion, temperature and relative humidity is especially studied.

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Résumé L'article rapporte des expériences faites avec un compteur automatique de noyaux de condensation, qui auparavant déjà a été décrit dans cette revue. Il examine en particulier la dépendance du nombre des noyaux mesuré du degré d'expansion, de la température et de l'humidité relative et décrit aussi la mise au point d'une sensibilité constante.

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Mit 6 Textabbildungen.     

Daily Weather Observations in Sixteenth-Century Europe

Thirty-two weather diaries written in astronomical calendars in central Europe in the late fifteenth and sixteenth centuries are presented and discussed. Systematic weather observations were promoted by the rise of planetary astronomy and its application in astro-meteorology. The practice of keeping weather diaries spread from Cracow (Poland) to Ingolstadt (Germany) and from there to other universities. The data obtained from these sources provided the backbone for setting up series of precipitation indices for Poland, Germany and Switzerland. Monthly statistics of days with precipitation, snowfall and frost were computed by counting the relevant entries in the most important diaries. The results were compared with either those obtained from instrumental measurements in the same place or with those from modern instrumental measurements in a neighbouring place. The final results show that autumn was considerably colder in the early sixteenth century. April was considerably drier and July was wetter during the period 1508-1531 than during 1901-1960. In order to highlight the impact of weather patterns on grain prices in a year of crisis, the timing of wet and dry spells in southern Poland and southern Germany is compared for the year 1529. Winters became 1.7°C colder from 1564 to 1576 and the month of July tended to be wetter than in 1901-1960. Details noted in the diaries kept between 1585 and 1600 by the astronomers Brahe (near Copenhagen) and Fabricius (in the Ostfriesland region of northwestern Germany) closely agree. It rained more often in June and July and temperatures dropped. The winter months were more frequently dominated by winds from easterly directions, the frequency of snowfall was higher and a deficit occurred in precipitation. This points to a higher frequency of high pressure in the Fennoscandian area with cold air advection from the east or northeast.     

Amplitude Response of a LCR Gravimeter with Feedback at Periods of Microseisms and Earthquake Waves

The amplitude response of a LCR gravimeter with the SRW-E feedback was determined on a vertical vibrating platform. The ink-pen recorder was connected parallel with the digital voltmeter input to obtain an analog response of the gravimeter to the harmonic motion of the base with a peak-to-peak amplitude of 10 m and periods excited in an interval of 4 - 10 s as by the ground motion of meteorological microseisms, and in the interval 10 -100 s as by surface waves of distant strong earthquakes. In the first interval, an unexpected maximum of the amplitude response was observed with the double amplitude of apparent 6,5 Gal (6.5 × 10 _–8 m/s ² ) at a period of 4.8 s, and a baseline shift with the amplitude of–64Gal was observed at the same period. The value of this direct component cannot be separated from the effect of the Earth's gravity field. In the second interval, the amplitude response of the gravimeter displayed one expected maximum at a period of 40 s with the double amplitude of 8.1Gal. At the usual level of microseisms with a peak-to-peak amplitude of up to 2 m the fluctuation of the gravimeter on the direct baseline shifted by –4.9 Gal was estimated at 1 Gal. With typical Rayleigh surface waves with periods of 20 s and double amplitudes of up to 100 m, the fluctuation reached 67 Gal.     

Differences between Mean Sea Levels for the Pacific,Atlantic and Indian Oceans From Topex/Poseidon Altimetry

Geopotential values W of the mean equipotential surfaces representing the mean ocean topography were computed on the basis of four years (1993 - 1996) TOPEX/POSEIDON altimeter data: W = 62 636 854.10m ² s ^–2 for the Pacific (P), W = 62 636 858.20m ² s ^–2 for the Atlantic (A), W = 62 636 856.28m ²s^–2 for the Indian (I) Oceans. The corresponding mean separations between the ocean levels were obtained as follows: A – P = – 42 cm, I– P = – 22 cm, I – A = 20 cm, the rms errors came out at about 0.3 cm. No sea surface topography model was used in the solution.     

Long transequatorial interconnecting loops of the new solar cycle

We study two long transequatorial loops connecting high-latitude regions of the new solar cycle. These loops (with lengths of 47 and 61 heliographic degrees) provide evidence that the upper length limit of 37° found by Chase et al. (1976) from Skylab data was determined simply by the typical distances between northern and southern active regions during the period of Skylab observations. We find strong support for the idea that these long interconnecting loops originate through reconnection of field lines extending from the two active regions towards and beyond the equator, and confirm the earlier finding by Canfield, Pevtsov, and McClymont (1996) that only field lines from active regions with the same chirality reconnect. As we are not aware of any longitudinal (E–W) loops of comparable lengths, we suggest that it is mainly the solar differential rotation which drives the reconnection of latitudinal (N–S) field lines.     

Adaptive neuro-fuzzy inference system coupled with shuffled frog leaping algorithm for predicting river streamflow time series

ABSTRACT

Accurate runoff forecasting plays a key role in catchment water management and water resources system planning. To improve the prediction accuracy, one needs to strive to develop a reliable and accurate forecasting model for streamflow. In this study, the novel combination of the adaptive neuro-fuzzy inference system (ANFIS) model with the shuffled frog-leaping algorithm (SFLA) is proposed. Historical streamflow data of two different rivers were collected to examine the performance of the proposed model. To evaluate the performance of the proposed ANFIS-SFLA model, six different scenarios for the model input–output architecture were investigated. The results show that the proposed ANFIS-SFLA model (R² = 0.88; NS = 0.88; RMSE = 142.30 (m³/s); MAE = 88.94 (m³/s); MAPE = 35.19%) significantly improved the forecasting accuracy and outperformed the classic ANFIS model (R² = 0.83; NS = 0.83; RMSE = 167.81; MAE = 115.83 (m³/s); MAPE = 45.97%). The proposed model could be generalized and applied in different rivers worldwide.     

A hyperspectral experiment over tropical forests based on the EO-1 orbit change and PROSAIL simulation

ABSTRACT

We designed a unique hyperspectral experiment from the Earth Observing One (EO-1) orbit change to evaluate solar illumination effects over tropical forests in Brazil. Ten nadir-viewing Hyperion images collected over a fixed site and period of the year (July to August) were selected for analysis. We evaluated variations in reflectance and in 16 narrowband vegetation indices (VIs) with increasing solar zenith angle (SZA) from the pre-drift (2004–2008) to the EO-1 drift period (2011–2016). To detect changes in reflectance and shadows, we applied spectral mixture analysis (SMA) and principal component analysis (PCA) and calculated the similarity spectral angle (θ) between the vegetation spectra measured with variable SZA. The magnitude of the illumination effects was also evaluated from change-point analysis and nonparametric Mann-Whitney U tests applied over the time series. Finally, we complemented our experiment using the PROSAIL model to simulate the VIs variation with increasing SZA resultant from satellite drift. The results showed significant changes in Hyperion reflectance and VIs, especially when the EO-1 crossed the study area at earlier times and larger SZA in 2015 (9:05 a.m.; SZA = 59°) and 2016 (8:30 a.m.; SZA = 67°). Compared to the pre-drift period (10:30 a.m.; SZA = 45°), the SZA differences of 14° (2015) and 22° (2016) increased the shade fractions and decreased the vegetation brightness. PCA separated the pre-drift and drift reflectance datasets, showing shifts in scores due to changes in brightness. θ increased with SZA, indicating changes in the shape of the vegetation spectra with drift. For most VIs, the change-point analysis indicated 2015 (SZA = 59°) as the predominant year of detected changes. Compared to the EO-1 original orbit, the Plant Senescence Reflectance Index (PSRI), Anthocyanin Reflectance Index (ARI) and Structure Insensitive Pigment Index (SIPI) presented the largest positive changes during drift, while the Photochemical Reflectance Index (PRI), Visible Atmospherically Resistant Index (VARI) and Enhanced Vegetation Index (EVI) had the largest negative changes. The effect size of the illumination geometry on these VIs was large, as indicated by increasing values of the Cohen’s r metric toward 2016. The anisotropy of the Hyperion VIs was generally consistent with that from PROSAIL in the simulated pre-drift and drift periods. Focusing on structural indices, it affected the relationships between VIs and simulated leaf area index (LAI) at large SZA.     

Hydration shell structures in a LiI solution at elevated temperature and pressure: a molecular dynamics study

Molecular dynamics simulations of a 0.55 molal aqueous LiI solution have been performed at 508 K and 308 K and a density of 1.05 g/cm³. The structural changes resulting from increased temperature and pressure are discussed.