Ice crystal shape effects on solar radiative properties of Arctic mixed-phase clouds—Dependence on microphysical properties     

Andr Ehrlich  Manfred Wendisch  Eike Bierwirth  Andreas Herber  Alfons Schwarzenbck 《Atmospheric Research》2008,88(3-4):266-276

Based on 1-year cloud measurements with radar and microwave radiometer broadband solar radiative transfer simulations were performed to quantify the impact of different ice crystal shapes of Arctic mixed-phase clouds on their radiative properties (reflectance, transmittance and absorptance). The ice crystal shape effects were investigated as a function of microphysical cloud properties (ice volume fraction f_i, ice and liquid water content IWC and LWC, mean particle diameter D_m^I and D_m^W of ice/water particle number size distributions, NSDs).The required NSDs were statistically derived from radar data. The NSD was composed of a liquid and a solid mode defined by LWC, D_m^W (water mode) and IWC, D_m^I (ice mode). It was found that the ratio of D_m^I and D_m^W determines the magnitude of the shape effect. For mixed-phase clouds with D_m^I ≤ 27 μm a significant shape effect was obtained. The shape effect was almost insensitive with regard to the solar zenith angle, but highly sensitive to the ice volume fraction of the mixed-phase cloud. For mixed-phase clouds containing small ice crystals (D_m^I ≤ 27 μm) and high ice volume fractions (f_i > 0.5) crystal shape is crucial. The largest shape effects were observed assuming aggregates and columns. If the IWC was conserved the shape effect reaches values up to 0.23 in cloud reflectance and transmittance. If the ice mode NSD was kept constant only a small shape effect was quantified (≤ 0.04).  相似文献   

Editorial: Special Issue on Risk Aware     

Manfred Dorninger  Pier Paolo Alberoni 《Meteorology and Atmospheric Physics》2008,101(3-4):109-110

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Major and trace elements in German bottled water,their regional distribution,and accordance with national and international standards     

Manfred Birke  Uwe Rauch  Bodo Harazim  Hans Lorenz  Wolfgang Glatte 《Journal of Geochemical Exploration》2010

The market for mineral water has been growing steadily over the last few years. Germany is the country with the highest number of bottled mineral water brands (908 bottled water samples from 502 wells/brands were analyzed). The per capita consumption of mineral water in Germany in 2003 was 129 L. A wide range of values of one to seven orders of magnitude was determined for 71 elements in the bottled water samples analyzed by ICP-QMS, ICP-AES, IC, titration, photometric, conductometric and potentiometric methods. A comparison of the element concentrations and the legal limits for both bottled and tap water (EU, Germany, US EPA, WHO) shows that only 70% of the 908 mineral water samples fulfill the German and EU drinking water (i.e., tap water) regulations for all parameters (not including pH) for which action levels are defined. Nearly 5% of the bottled water samples not fulfill the German and EU regulations for mineral and table water. Comparison of our results with the current German and European action levels for mineral and table water shows that only 42 of the bottled water samples exceed the limits for one or more of the following elements: arsenic, nitrate, nitrite, manganese, nickel and barium concentrations. Ten of the bottled water samples contain uranium concentrations above the 10 μg/L recommended limit.  相似文献   

(Na,Ca)(Ti3+,Mg)Si2O6-clinopyroxenes at high pressure: influence of cation substitution on elastic behavior and phase transition     

Angela Ullrich  Ronald Miletich  Tonci Balic-Zunic  Lars Olsen  Fabrizio Nestola  Manfred Wildner  Haruo Ohashi 《Physics and Chemistry of Minerals》2010,37(1):25-43

A compressional study of (Na,Ca)(Ti³⁺,Mg)Si₂O₆-clinopyroxenes was carried out at high pressures between 10⁻⁴ and 10.2 GPa using in situ single-crystal X-ray diffraction, Raman spectroscopy and optical absorption spectroscopy. Compressional discontinuities accompanied by structural changes, in particular, the appearance of two distinct Ti³⁺–Ti³⁺ distances within the octahedral chains at 4.37 GPa, provide evidence for the occurrence of a phase transition in NaTi³⁺Si₂O₆. Equation-of-state parameters are K ₀ = 115.9(7) GPa with K′ = −0.9(3) and K ₀ = 102.7(8) GPa with K′ = 4.08(5) for the low- and high-pressure range, respectively. The transition involves a C2/c–P [`1] \overline{1} symmetry change, which can be confirmed by the occurrence of new modes in Raman spectra. Since no significant discontinuity in the evolution of the unit-cell volume with pressure has been observed, the transition appears to be second-order in character. The influence of the coupled substitution Na⁺Ti³⁺↔Ca²⁺Mg²⁺ on the static compression behavior and the structural stability has been investigated using a sample of the intermediate composition (Na_0.54Ca_0.46)(Mg_0.46Ti_0.54)Si₂O₆. No evidence for a deviation from continuous compression behavior has been found, neither in lattice parameter nor in structural data and the fit of a third-order Birch–Murnaghan equation-of-state to the pressure–volume data yields a bulk modulus of K ₀ = 109.1(5) GPa and K′ = 5.02(13). Raman and polarized absorption spectra have been compared to NaTiSi₂O₆ and reveal major similarities. The main driving force for the phase transition in NaTi³⁺Si₂O₆ is the localization of the Ti³⁺ d-electron and the accompanying distortion, which is suppressed in the (Na,Ca)(Ti³⁺,Mg)Si₂O₆-clinopyroxene.  相似文献   

An early Daonella from the Middle Anisian of Guangxi, southwestern China, and its phylogenetical significance     

Jin-hua Chen  Frank Stiller 《Swiss Journal of Geoscience》2010,103(3):523-533

The late Middle Anisian Daonella fengshanensis sp. nov. from the upper part of the Lower Member of the Banna Formation near Jinya in northwestern Guangxi, southwestern China, represents the earliest appearance of Daonella in this region. With regard to stratigraphical occurrence as well as morphological features the new species is in a transitional position between Enteropleura and more derived species of Daonella. The new species is an early representative of the genus Daonella and regarded as phylogenetically being near the genus’ origin. It is characterised by a small posterior auricle similar to Enteropleura and flat-topped radial ribs resembling later species of Daonella. Its anterior shell sector is large. The shell sculpture of juvenile stages closely resembles both Daonella and Enteropleura, supporting the hypothesis that Daonella may have evolved from Enteropleura.  相似文献   

Book reviews     

Rudnicki  John W.  Zheng  Gutuan  Koch  Manfred  Hanyga  Andrzej  Fujinawa  Yukio  Tabeart  Frazer  Kimbrough  David L.  Lovison-Golob  Lucía  Dore  Anthony  Blecki  Jan  Sroczynska-Kozuchowska  Magdalena 《Pure and Applied Geophysics》1993,140(3):537-556

Pure and Applied Geophysics -  相似文献   

Simultaneous Inversion For 3-D Crustal Structure and Hypocentres Including Direct, Refracted and Reflected Phases-I. Development, Validation and Optimal Regularization of the Method     

Manfred Koch 《Geophysical Journal International》1993,112(3):385-412

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Simultaneous Inversion For 3-D Crustal Structure and Hypocentres Including Direct, Refracted and Reflected Phases-Iii. Application to the Southern Rhine Graben Seismic Region, Germany     

Manfred Koch 《Geophysical Journal International》1993,112(3):429-447

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Carbon isotope geochemistry of the Precambrian Lomagundi carbonate province,Rhodesia   总被引：1，自引：0，他引：1  

Manfred Schidlowski  Rudolf Eichmann  Christian E. Junge 《Geochimica et cosmochimica acta》1976,40(4):449-455

Carbon isotope measurements carried out on 67 dolomite samples from the Middle Precambrian Lomagundi Group (Rhodesia) have yielded a δ¹³C mean of +8.2 ± 2.6%. vs PDB. With the outcrop of these dolomites extending over a distance of almost 300 km, the Lomagundi dolomite faces is likely to represent the largest isotopically anomalous sedimentary carbonate province ever recorded. It is concluded that the anomalous carbonates formed in a closed basin whose δ¹³C level had been substantially increased as a result of a preferential removal (within sedimentary organics) of the light carbon isotope.  相似文献   

Coupling among the terrestrial sulfur,carbon and oxygen cycles: numerical modeling based on revised Phanerozoic carbon isotope record     

Manfred Schidlowski  Christian E Junge 《Geochimica et cosmochimica acta》1981,45(4):589-594

Numerical modeling of the terrestrial oxygen budget based on the revised δ¹³C_carb record by Veizeret al. (1980) has shown that total photosynthetic oxygen has varied between ±7% and ±10% of its average reservoir size (～3.2 × 10²² g) during the last 800 myr as a result of oscillations of the sedimentary reservoir of organic carbon. Calculated curves of oxygen evolution display a distinct minimum in the Early Paleozoic framed by two maxima in the Latest Proterozoic and the Mesozoic. The sympathetic relationship observed between the curves of total oxygen evolution and respective functions for the partial reservoir of sulfate-bound oxygen suggests that the O₂ required for an additional conversion of sulfide to sulfate was most probably provided by excess burial of organic carbon, the results of the modeling thus adding credence to current interpretations proposed for the negative correlation between the secular ${}^{13}\text{C}{}^{12}\text{C}$ and ${}^{34}\text{S}{}^{32}\text{S}$ trends.  相似文献