Improvement of the photometric sunspot index and changes of thedisk-integrated sunspot contrast with time     

Claus Fröhlich  Judit M. Pap  Hugh S. Hudson 《Solar physics》1994,152(1):111-118

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Temporal trends of dissolved weathering products released from a high Arctic coal mine waste rock pile in Svalbard (78°N)     

Jens Søndergaard  Bo Elberling  Gert Asmund  Claus Gudum  Karl Martin Iversen 《Applied Geochemistry》2007

It is well known that oxidation of sulphide-containing coal mine waste has considerable environmental impacts due to generation of acid mine drainage (AMD) containing high dissolved metal concentrations. This study is the first to evaluate seasonal trends in the release of AMD from high arctic coal mine waste rock. Runoff from an abandoned coal mine waste pile in Svalbard (78°N) was studied during the entire 3–4 month period with running water in 2005. Temporal variation in concentrations and fluxes of dissolved elements were quantified based on daily water sampling and used to evaluate weathering processes and estimate element budgets on a daily, seasonal and annual basis. Apart from alkali- and alkaline earth metals; Fe, Al, Mn, Zn and Ni were found to be the most abundant metals in the runoff. Element concentrations were highly correlated and suggest that the processes of sulphide oxidation, ion exchange and silicate weathering occurring within the waste pile were linked throughout the measuring period. Observed pH values varied from 2.8 to 5.2 and SO₄ concentrations from 21 to 1463 mg L⁻¹. Manganese and Al concentrations were observed above phytotoxic levels (up to 4 and 23 mg L⁻¹, respectively) and were considered the most critical elements in terms of environmental impact. Throughout the summer a total dissolved quantity of 58 kg Mn, 238 kg Al and 13,700 kg SO₄ was released from the pile containing approximately 200,000 m³ of pyritic waste material (<1% FeS₂). The highest concentrations of metals, lowest pH values and a very high daily release of H₂SO₄ (up to twice as high as the following month) were observed during the first week of thaw. This is considered a result of an accumulation of weathering products, generated within the waste pile during winter and released as a pollution-flush during early spring. Similar accumulation/flush sequences were observed later in the summer where rain events following relatively long dry periods caused high daily metal fluxes and on some occasions also elevated dissolved metal concentrations. Despite highly variable weather/climate conditions during the rest of the summer the investigated waste rock pile acted like a relative constant pollution-source during this period. Future investigations regarding the environmental impact of mine waste in the region should include measurements of bioavailable metals in order to provide further details on the seasonal trends in environmental impact.  相似文献   

The Enigmatic Behaviour of the Old Nova RR Pic     

Linda Schmidtobreick  Claus Tappert  Alessandro Ederoclite  Ivo Saviane  Elena Mason 《Astrophysics and Space Science》2006,304(1-4):303-305

We report preliminary results of an observing run at the 1--m telescope at CTIO during which we followed RR Pic over several nights in February 2005. The resulting light curves show no sign of an eclipse. Apart from the 3.48 h period, which is usually interpreted as the orbital one, we find an additional period at P=3.78 h, which we interpret as the superhump period of the system.We furthermore present high–resolution Doppler maps in Hα, Hβ and He II, which we derived from observations at the NTT, La Silla in February 2004. They show strong variations in the emission distribution from one day to the next. While Hα and Hβ emission clearly show the accretion disc with some additional isolated sources, the He II emission is confined to an elongated region at low velocities.  相似文献   

Holocene Climate Variability in Antarctica Based on 11 Ice-Core Isotopic Records   总被引：1，自引：0，他引：1  

Valrie Masson  Franoise Vimeux  Jean Jouzel  Vin Morgan  Marc Delmotte  Philippe Ciais  Claus Hammer  Sigfus Johnsen  Vladimir Ya. Lipenkov  E. Mosley-Thompson  Jean-Robert Petit  Eric J. Steig  Michel Stievenard  Rein Vaikmae 《Quaternary Research》2000,54(3):348

A comparison is made of the Holocene records obtained from water isotope measurements along 11 ice cores from coastal and central sites in east Antarctica (Vostok, Dome B, Plateau Remote, Komsomolskaia, Dome C, Taylor Dome, Dominion Range, D47, KM105, and Law Dome) and west Antarctica (Byrd), with temporal resolution from 20 to 50 yr. The long-term trends possibly reflect local ice sheet elevation fluctuations superimposed on common climatic fluctuations. All the records confirm the widespread Antarctic early Holocene optimum between 11,500 and 9000 yr; in the Ross Sea sector, a secondary optimum is identified between 7000 and 5000 yr, whereas all eastern Antarctic sites show a late optimum between 6000 and 3000 yr. Superimposed on the long time trend, all the records exhibit 9 aperiodic millennial-scale oscillations. Climatic optima show a reduced pacing between warm events (typically 800 yr), whereas cooler periods are associated with less-frequent warm events (pacing >1200 yr).  相似文献   

Developments in Astrophysics     

Gudrun Wolfschmidt  Claus Kiefer 《Astronomische Nachrichten》2005,326(7):635-645

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The impact of spatial scale: exploring urban butterfly abundance and richness patterns using multi-criteria decision analysis and principal component analysis     

Emily C. Hazell  Claus Rinner 《International journal of geographical information science》2020,34(8):1648-1681

ABSTRACT

Modelling changes in biodiversity have become a necessary component of smart urban planning practices. However, concepts such as biodiversity are often evaluated using area-based composite indices, the results of which are heavily reliant on specific parameters chosen. This paper explores the design and implementation of a butterfly biodiversity index by comparing two widely accepted modelling techniques: principal component analysis and spatial multi-criteria decision analysis (MCDA). A high degree of scale dependency has been demonstrated in previous studies exploring the use of area-based composite measures. To evaluate the impact of scale, each model was assessed at two different spatial resolutions. The outcomes were analyzed, mapped and compared using ordinary least squares, geographically weighted regression and global Moran’s I to evaluate relative biodiversity patterns across the City of Toronto, Canada. Findings indicate that the impact of spatial scale was significant, whereby the coarser resolution models were found to be more highly correlated with biodiversity, compared to the finer resolution models. The results of this study contribute to a growing body of literature that explores key conceptual questions regarding the robustness of GIS-based MCDA, the impact of scale in urban ecology studies, and the use of composite indices to manage spatial ecological data.  相似文献   

FIRST RESULTS FROM VIRGO,THE EXPERIMENT FOR HELIOSEISMOLOGY AND SOLAR IRRADIANCE MONITORING ON SOHO   总被引：1，自引：0，他引：1  

Fröhlich  Claus  Andersen  Bo N.  Appourchaux  Thierry  Berthomieu  Gabrielle  Crommelynck  Dominique A.  Domingo  Vicente  Fichot  Alain  Finsterle  Wolfgang  Gómez  Maria F.  Gough  Douglas  Jiménez  Antonio  Leifsen  Torben  Lombaerts  Marc  Pap  Judit M.  Provost  Janine  Roca Cortés  Teodoro  Romero  José  Roth  Hansjörg  Sekii  Takashi  Telljohann  Udo  Toutain  Thierry  Wehrli  Christoph 《Solar physics》1997,170(1):1-25

First results from the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The observations started mid-January 1996 for the radiometers and sunphotometers and near the end of March for the luminosity oscillation imager. The performance of all the instruments is very good, and the time series of the first 4–6 months are evaluated in terms of solar irradiance variability, solar background noise characteristics and p-mode oscillations. The solar irradiance is modulated by the passage of active regions across the disk, but not all of the modulation is straightforwardly explained in terms of sunspot flux blocking and facular enhancement. Helioseismic inversions of the observed p-mode frequencies are more-or-less in agreement with the latest standard solar models. The comparison of VIRGO results with earlier ones shows evidence that magnetic activity plays a significant role in the dynamics of the oscillations beyond its modulation of the resonant frequencies. Moreover, by comparing the amplitudes of different components ofp -mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation.  相似文献   

Orbit and rotation of the Moon by numerical integration     

Claus Oesterwinter 《Celestial Mechanics and Dynamical Astronomy》1982,26(2):143-143

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Spectroscopy of the Candidate Pre-CV LTT 560     

Claus Tappert  Boris T. Gänsicke  Ronald E. Mennickent  Linda Schmidtobreick 《Astrophysics and Space Science》2006,304(1-4):299-301

We present preliminary results on spectroscopic data of the candidate pre-cataclysmic variable LTT 560. A fit to the flux-calibrated spectrum reveals the temperature of the white-dwarf primary to be T _eff=7000–7500 K, and confirms the result of previous studies on the detection of an M5V secondary star. The analysis of radial velocity data from spectral features attributed to the primary and the secondary star show evidence for low-level accretion.  相似文献   

Investigating the redox sensitivity of para-toluenesulfonamide (p-TSA) in groundwater     

Raffaella Meffe  Gudrun Massmann  Claus Kohfahl  Thomas Taute  Doreen Richter  Uwe Dünnbier  Asaf Pekdeger 《Environmental Earth Sciences》2012,65(3):861-870

The groundwater downstream of a former sewage irrigation farm in Berlin is contaminated with ammonium (NH₄ ⁺) and para-toluenesulfonamide (p-TSA), besides other anthropogenic pollutants. In the field, in situ removal of NH₄ ⁺ by gaseous oxygen (O₂) and air injection is currently being tested. A laboratory column experiment using aquifer material and groundwater from the site was performed to determine whether this remediation technology is also feasible to reduce high p-TSA concentrations in the anoxic groundwater. First, the column was operated under anoxic conditions. Later, compressed air was introduced into the system to simulate oxic conditions. Samples were collected from the column outlet before and after the addition of compressed air. The experiment revealed that whereas p-TSA was not removed under anoxic conditions, it was almost fully eliminated under oxic conditions. Results were modelled using a transient one-dimensional solute transport model. The degradation rate constants for p-TSA increased from 2.8E−06 to 7.5E−05 s^–1 as a result of microbial adaption to the change of redox conditions. Results show that O₂ injection into an anoxic aquifer is a successful strategy for p-TSA remediation.  相似文献