Evaluating the Ability of CRCM5 to Simulate Mixed Precipitation

Precipitation episodes in the form of freezing rain and ice pellets represent natural hazards affecting eastern Canada during the cold season. These types of precipitation mainly occur in the St. Lawrence River valley and the Atlantic provinces of Canada. This study aims to evaluate the ability of the fifth-generation Canadian Regional Climate Model (CRCM5), using a 0.11° horizontal grid mesh, to hindcast mixed precipitation when driven by reanalyses produced by the European Centre for Medium-range Weather Forecasts (ERA-Interim) for a 35-year period. In general, the CRCM5 simulation slightly overestimates the occurrence of freezing rain, but the geographical distribution is well reproduced. The duration of freezing rain events and accompanying surface winds in the Montréal region are reproduced by CRCM5. A case study is performed for an especially catastrophic freezing-rain event in January 1998; the model succeeds in simulating the intensity and duration of the episode, as well as the propitious meteorological environment. Overall, the model is also able to reproduce the climatology and a specific event of freezing rain and ice pellets.     

Contribution a la tectonique du Bassin houiller de la Sarre: Recherche du tracé au sol de la Faille de la Sarre et de la Faille de la Rosselle (Faille Felsberg)

Zusammenfassung Es werden genauere Angaben gemacht über den Verlauf des Saarsprungs und des Felsbergsprunges an der Erdoberfläche. Der Saarsprung konnte von Bous bis Burbach verfolgt werden. Der Felsbergsprung verfolgt sich nach SE bis in den Rosselsprung.Das Vorkommen von Oberrotliegendem scheint an diese Verwerfungen gebunden zu sein. Es sind Zerrungsspalten, die während der Hauptfaltungsphase (saalische Phase nachStille) des Saar-Nahe-Beckens aufgebrochen sind. Es ist aber anzunehmen, daß sie während des Oberrotliegenden aktiv waren. Sie wurden nach Ablagerung der Trias neu belebt.     

Tiergeschichte oder Erdgeschichte?

Ohne Zusammenfassung     

The planet Jupiter

Summary. The exploration of Jupiter, the closest and biggest giant planet, has provided key information about the origin and evolution of the outer Solar system. Our knowledge has strongly benefited from the Voyager and Galileo space missions. We now have a good understanding of Jupiter's thermal structure, chemical composition and magnetospheric environment. There is still debate about the nature of the heating source responsible for the high thermospheric temperatures (precipitating particles and/or gravity waves). The measurement of elemental abundance ratios (C/H, N/H, S/H) gives strong support to the “nucleation” formation model, according to which giant planets formed from the accretion of an initial core and the collapse of the surrounding gaseous protosolar nebula. The D/H and He/He ratios are found to be representative of their protosolar value. The helium abundance, in contrast, appears to be slightly depleted in the outer envelope with respect to the protosolar value; this departure is interpreted as an evolutionary effect, due to the condensation of helium droplets in the liquid hydrogen ocean inside Jupiter's interior. The cloud structure of Jupiter, characterized by the belt-zone system, is globally understood; also present are specific features like regions of strong infrared radiation (“hot spots”), colder regions (“white ovals”) and the Great Red Spot (GRS). Clouds were surprisingly absent at the hot spot corresponding to the Galileo probe entry site, and the water abundance measured there was strongly depleted with respect to the solar O/H value. This probably implies that hot spots are dry, cloud-free regions of subsidence, while “normal” air, rich in condensibles, is transported upward by convective motions. As a result, the Jovian meteorology, still based on Halley-type cells, seems to be much more complex than a simple zone-belt system. The nature of the GRS, a giant anticyclonic storm, colder and higher than its environment, has been confirmed by the Galileo observations, but its internal structure appears to be very complex. Strong winds, probably driven by the Jovian internal source, were measured at deep tropospheric levels. The troposphere might be statically stable at pressures higher than 18 bars, but the extent of this putative radiative layer is still unknown. Received 23 November 1998     

A mass ratio limit for primordial black holes

We augment our scenario for the formation of astronomical objects from macroscopic superstrings by the assumption that the central matter keeps its identity in the fragmentation. From the condition that the angular momentum per mass squared of this matter should be less than the Kerr limit G/c, we obtain upper limits for the ratio of the mass of central black holes M(BH) to the mass M of the host object. This limit is M(BH)/M ≈ 0.001, and, expressed in observed quantities, approximately M(BH)/M ≈ σ²/(v · c) where σ is the r.m.s. velocity, v the rotational velocity and c the velocity of light. The valuesM(BH) agree with the observed behaviour both in order of magnitude and in the variation with velocity dispersion. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Narrow-line Seyfert 1 galaxies

This paper summarizes the soft X-ray properties of narrow-line Seyfert 1 galaxies (NLS1). NLS1 have generally steeper soft X-ray continuum slopes than Seyfert 1s with broader lines, and there exists an anticorrelation between 0.1–2.4 keV continuum slope and the FWHM of the Hβ line. Objects with steep 0.1–2.4 keV continuum slopes and Hβ FWHM > 3000 km s⁻¹ are clearly discriminated against by nature. When simple power-law models are fit to the data, photon indices reach values up to about 5, much higher than is usually seen in Seyfert 1s. Models with smaller mass black holes and/or higher Eddington fractions show some promise to explain the relation between the FWHM of the Hβ line and the X-ray continuum slope. We further report evidence for persistent gaint and rapid variability in the ultrasoft narrow-line Seyfert 1 galaxy IRAS 13224–3809. We have examined possible explanations for the gaint variability. Unusually strong relativistic effects provide a plausible explanation of the X-ray data. Relativistic boosting effects may be relevant to understanding the strong X-ray variability of some steep spectrum Seyferts more generally.     

Dissolved Carbohydrate Concentration,Composition, and Bioavailability to Microbial Heterotrophs in Stream Water

Dissolved total carbohydrates (DTCH), dissolved free monosaccharides (DFMS), dissolved organic carbon (DOC), biodegradable DOC (BDOC), and humic substances (HS) were measured in White Clay Creek (WCC), a stream in southeastern Pennsylvania Piedmont, USA. Samples were collected over different seasons and under baseflow and stormflow conditions. DOC concentrations ranged from 1.0 to 12.8 mg/L C with the highest concentrations associated with stormflows. Carbohydrates ranged from 0.42 to 12.4 μM and accounted for 2.9 to 12.7% of the DOC. Humic substances represented the major DOC fraction, accounting for 55 to 72% of the DOC pool under all flow conditions. The humic fraction had a lower carbohydrate content (4.4%) than the non-humic fraction of DOC (7.2%). Stormflow DOC was enriched in carbohydrates relative to baseflow DOC, but the percentage of humic-C changed little. Carbohydrates were primarily present as dissolved polysaccharides (55%), but a significant fraction was bound to humic substances (40%), while a small proportion was present as monosaccharides (5%). The major monosaccharides in stream water, listed in order of decreasing concentration, included glucose, galactose, rhamnose, xylose, arabinose, mannose, and fucose. On average (30.6 ± 7.4)% (n = 44) of the stream water DOC was biodegradable, and carbohydrates accounted for 9.9 to 17.7% of the BDOC.     

Occurrence and Distribution of Organic Contaminants in the Aquatic System in Berlin. Part III: Determination of Synthetic Musks in Berlin Surface Water Applying Solid-phase Microextraction (SPME) and Gas Chromatography-Mass Spectrometry (GC-MS)

Polycyclic musks and nitro musks were found as environmental pollutants in screening analyses of 30 representative surface water samples collected from rivers, lakes, and canals in Berlin. These synthetic musks, which are used as fragrances in cosmetics, detergents, and other products, are discharged by the municipal sewage treatment plants into Berlinπs surface waters. In particular, the polycyclic musks 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyrane (HHCB; Galaxolide®, Abbalide®) and 7-acetyl-1,1,3,4,4,6-hexamethyltetraline (AHTN; Tonalide®, Fixolide®) were found in the receiving surface waters at considerable concentrations up to the μg/L-level. In the Wuhle, a small brook almost totally consisting of sewage effluents, maximum concentrations were 12.5 μg/L for HHCB and 6.8 μg/L for AHTN. Additionally, the polycyclic musk 4-acetyl-1,1-dimethyl-6-tert-butylindane (ADBI; Celestolide®, Crysolide®) and 1-tert-butyl-3,5-dimethyl-2,6-dinitro-4-acetylbenzene (musk ketone) were detected at low concentrations in most of the samples. Two other nitro musks, namely 1,1,3,3,5-pentamethyl-4,6-dinitroindene (musk moskene) and 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene), were only detected in a single surface water sample. Solid-phase microextraction (SPME) with detection by gas chromatography-mass spectrometry (GC-MS) has proven to be a rapid and reliable tool for the screening of synthetic musks in surface and sewage water samples. Internal calibration with a suitable internal standard enables reproducible quantitation of the analytes down to the low ng/L-level.     

Occurrence and Distribution of Organic Contaminants in the Aquatic System in Berlin.Part II: Substituted Phenols in Berlin Surface Water

In a surface water screening, 30 representative surface water samples collected from rivers, canals, and lakes in Berlin were investigated for the presence of 22 substituted phenols. The phenols selected include the 11 phenols considered as “priority pollutants” by the US Environmental Protection Agency (US-EPA). Surface water samples were extracted applying solid-phase extraction with styrenedivinylbenzene adsorbent. The recoveries, determined in spiking experiments, were between 80 % and 103 %. After derivatization with N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide (MTBSTFA) the samples were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Phenol, cresols, 2-ethylphenol, 2-chlorophenol, 4-chloro-3-methylphenol, pentachlorophenol, 2-nitrophenol, and 4-nitrophenol were detected in the surface water samples at concentrations between 0.02 μg/L and 7.8 μg/L, respectively. The distribution of these residues in the Berlin surface waters showed that the phenolic residues, with the exception of pentachlorophenol and 2-ethylphenol, do not originate primarily from municipal sewage treatment plants discharges. Some of the phenols are formed naturally or occur as ubiquitous anthropogenic contaminants in the aquatic system.     

Modeling the Phase Transition Associated with Melting Snow in a 1D Kinematic Framework: Sensitivity to the Microphysics

A simple 1D kinematic cloud model coupled to a two-moment bulk microphysics scheme is used to perform quasi-idealized simulations of snow, with a prescribed upper boundary snow field based on observed radar reflectivity and temperature, falling into a low-level melting layer. The model realistically simulates the formation of a nearly isothermal layer below the melting level, the surface precipitation rate, and the phase transition from liquid to solid, consistent with observations for this case. A series of test runs is performed to examine the sensitivity of modeling the timing and duration of the phase transition period to details of specific parameterization aspects related to snow in the microphysics scheme. The sensitivity tests include varying the number of prognostic moments, the mass–diameter relation, the fall velocity–diameter relation, the treatment of aggregation, and the lower limit for the slope of the size distribution. It is shown that the simulated transition period, for such a case with the initial melting level being close to the surface, can be quite sensitive to model parameters specified within realistic ranges and/or ranges within our physical understanding.