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151.
152.
Monika Hölzel Kurt Decker András Zámolyi Philipp Strauss Michael Wagreich 《Marine and Petroleum Geology》2010
The tectonic evolution of the Vienna Basin overlying the Alpine-Carpathian fold and thrust belt includes two stages of distinct basin subsidence and deformation. The earlier phase contemporaneous with thrusting of the Alpine-Carpathian floor thrust is related to the formation of a wedge-top basin (“piggy-back”), which was connected to the evolving foreland basin (Lower Miocene; c. 18.5–16 Ma). This stage is followed by the formation of a pull-apart basin (Middle to Upper Miocene; c. 16–8 Ma). Sediments of the latter unconformably overly wedge-top basin strata and protected them against erosion. 相似文献
153.
A typical question in climate change analysis is whether a certain observed climate characteristic, like a pronounced anomaly or an interdecadal trend, is an indicator of anthropogenic climate change or still in the range of natural variability. Many climatic features are described by one-dimensional index time series, like for instance the global mean temperature or circulation indices. Here, we present a Bayesian classification approach applied to the time series of the northern annular mode (NAM), which is the leading mode of Northern Hemisphere climate variability. After a pronounced negative phase during the 1950s and 1960s, the observed NAM index reveals a distinct positive trend, which is also simulated by various climate model simulations under enhanced greenhouse conditions. The objective of this study is to decide whether the observed temporal evolution of the NAM may be an indicator of global warming. Given a set of prior probabilities for disturbed and undisturbed climate scenarios, the Bayesian decision theorem decides whether the observed NAM trend is classified in a control climate, a greenhouse-gas plus sulphate aerosol climate or a purely greenhouse-gas induced climate as derived from multi-model ensemble simulations.The three climate scenarios are well separated from each other in terms of the 30-year NAM trends. The multi-model ensembles contain a weak but statistically significant climate change signal in the form of an intensification of the NAM. The Bayesian classification suggests that the greenhouse-gas scenario is the most probable explanation for the observed NAM trend since 1960, even if a high prior probability is assigned to the control climate. However, there are still large uncertainties in this classification result because some periods at the end of the 19th century and during the “warm” 1920s are also classified in an anthropogenic climate, although natural forcings are likely responsible for this early NAM intensification. This demonstrates a basic shortcoming of the Bayesian decision theorem when it is based on one-dimensional index time series like the NAM index. 相似文献
154.
Ralf Milke Kornelia Kolzer Monika Koch-Müller Bernd Wunder 《Mineralogy and Petrology》2009,97(3-4):223-232
Orthopyroxene reaction rims were synthesized between polished plates of natural olivine or synthetic forsterite and quartz at 1.9 GPa and temperatures of 750–950°C. The experiments were performed in a piston-cylinder apparatus after drying the samples at 600°C. Each experiment comprised 4 or 7 quartz-olivine contacts that were positioned along a temperature gradient. As a monitor for water content in the samples, the water concentration in the two olivines was determined by FTIR before and after the experiments. The orthopyroxene layers show two different structural variants. Type one (normal layers) has very constant thickness at each contact and formed with equal growth rates at both interfaces. Type two (bulging layers) comprises more irregular areas with 3–5 times thicker rims where porosity provides evidence for the local presence of a fluid. In the bulging layers the growth rate at the olivine-orthopyroxene interface exceeds that at the quartz-orthopyroxene interface. The relative growth rates at the interfaces are in accordance with SiO2-immobile growth of the normal layers and SiO2-mobile growth of the bulging layers. The natural olivine contains about 60 wt-ppm intracrystalline water before and after experiment and took up about 20 wt-ppm water molecular adsorbed to micro- and nanocracks and -pores during the runs. The synthetic forsterite contains about 7 wt-ppm internally adsorbed molecular water before and after experiment, and during the runs took up hydrogen equivalent to 3 wt-ppm adsorbed water. The IR spectra indicate that large parts of the point defects (possibly tetrahedral) were frozen-in at the conditions of the experiments. In both olivines a new band appeared at 3,355 or 3,357 cm?1, respectively, equivalent to about 3 wt-ppm water that at the high pressure of the experiments and opx-buffered aSiO2 of the experiments might already mean water saturation of the olivines. Despite the effective drying before experiment and the absence of porosity, the bulk diffusivity derived from the rim growth rates is perfectly in line with data from water-bearing piston-cylinder experiments at higher temperatures. The bulk diffusivity during rim growth is 4 to 7 orders of magnitude higher than an extrapolation of really dry experiments to the temperature range of this study. 相似文献
155.
Petr Dobrovolný Anders Moberg Rudolf Brázdil Christian Pfister Rüdiger Glaser Rob Wilson Aryan van Engelen Danuta Limanówka Andrea Kiss Monika Halíčková Jarmila Macková Dirk Riemann Jürg Luterbacher Reinhard Böhm 《Climatic change》2010,101(1-2):69-107
Monthly temperature series for Central Europe back to AD 1500 are developed from documentary index series from Germany, Switzerland and the Czech Republic (1500–1854) and 11 instrumental temperature records (1760–2007). Documentary evidence from the Low Countries, the Carpathian Basin and Poland are used for cross-checking for earlier centuries. The instrumental station records are corrected for inhomogeneities, including insufficient radiation protection of early thermometers and the urban heat island effect. For overlapping period (1760–1854), the documentary data series correlate with instrumental temperatures, most strongly in winter (86% explained variance in January) and least in autumn (56% in September). For annual average temperatures, 81% of the variance is explained. Verification statistics indicate high reconstruction skill for most months and seasons. The last 20 years (since 1988) stand out as very likely the warmest 20-year period, accounting for the calibration uncertainty and decreases in proxy data quality before the calibration period. The new reconstruction displays a previously unobserved long-term decrease in DJF, MAM and JJA temperature variability over last five centuries. Compiled monthly, seasonal and annual series can be used to improve the robustness of gridded large-scale European temperature reconstructions and possible impact studies. Further improvement of the reconstruction would be achieved if documentary data from other European countries are further developed. 相似文献
156.
Jetta Satyanarayana Loka Arun Kumar Reddy Monika Jain Kulshrestha R Nageswara Rao Umesh Chandra Kulshrestha 《Journal of Atmospheric Chemistry》2010,66(3):101-116
Samples of rain water were collected during monsoon season (June to September) of 2006 and 2007 at Hudegadde, a rural site
located in an ecological sensitive area of Western Ghats. The collected samples were analyzed for pH, conductivity and major
ions. At this site, rainwater pH varied from 4.20 to 7.39 with 5.65 as volume weighed mean. The observed mean was slightly
lower than the average pH reported at most of the Indian continental sites. Monthly variation showed that average pH of rain
water was the lowest during September (end of monsoon) and the highest during July (peak of monsoon). Overall, marine sources
had dominating influence at this site. However, significant influence of anthropogenic and crustal sources from local as well
as inter-continental regions was also noticed. As compared to NO3−, higher concentration of SO42− was noticed which might be due to contribution from industrial activities responsible for SO2 emission. At this site, influence of five types of airmass trajectories was noticed i.e. i) C.I.O. (Central part of Indian
Ocean)-when air masses blown from Maldives and nearby region of central Indian ocean. These airmasses had higher concentrations
of nss Ca2+ which did not show any adverse impact on the pH; ii) N.W.I.O.(North-West Indian Ocean)-when airmasses travelled from oceanic region close to north-east Africa. These airmassses had higher
concentrations of nss sulphate and nitrate and gave rise to acid rain; iii) S.W.I.O. (South -West Indian Ocean)- when airmasses
came from southern part of Indian ocean (close to Mauritius). During these airmasses, rain water samples had almost equal
ratio of nss SO42− and nss Ca2+ similar to N.W.I.O but very low NO3− ; iv) Gulf-when airmasses were observed coming from Gulf region. Although these airmasses contributed only 2% of the total
number of samples but carried high amount of nss SO42− which gave rise to acid rain. The second lowest pH was observed during these airmasses which might be due to very high nssSO42−/nssCa2+ ratios; v) N.W.I.O. + S.W.I.C. (North-West Indian Ocean+South-West Indian Continental)- when airmasses originated from north-west
Indian Ocean travelling towards south continental part of India and then arriving to the site. During these airmasses, samples
showed typical influence of urban activities having high concentrations of nss SO42− and NO3− leading to the lowest pH of rain water. 相似文献
157.
Umesh C. Kulshrestha Ramya Sunder Raman Monika J. Kulshrestha T. N. Rao Partha J. Hazarika 《Journal of Atmospheric Chemistry》2009,63(1):33-47
Secondary aerosol formation was studied at Allahabad in the Indo-Gangetic region during a field campaign called Land Campaign-II
in December 2004 (northern winter). Regional source locations of the ionic species in PM10 were identified by using Potential Source Contribution Function (PSCF analysis). On an average, the concentration of water
soluble inorganic ions (sum of anions and cations) was 63.2 μgm−3. Amongst the water soluble ions, average NO3− concentration was the highest (25.0 μgm−3) followed by SO42− (15.8 μgm−3) and NH4+ (13.8 μgm−3) concentrations. These species, contributed 87% of the total mass of water soluble species, indicating that most of the water
soluble PM10 was composed of NH4NO3 and (NH4)2SO4/NH4HSO4 or (NH4)3H(SO4)2 particles. Further, the concentrations of SO42−, NO3−, and NH4+ aerosols increased at high relative humidity levels up to the deliquescence point (∼63% RH) for salts of these species suggesting
that high humidity levels favor the conversion and partitioning of gaseous SO2, NOx, and NH3 to their aerosol phase. Additionally, lowering of ambient temperature as the winter progressed also resulted in an increase
of NO3− and NH4+ concentrations, probably due to the semi volatile nature of ammonium nitrate. PSCF analysis identified regions along the
Indo-Gangetic Plain (IGP) including Northern and Central Uttar Pradesh, Punjab, Haryana, Northern Pakistan, and parts of Rajasthan
as source regions of airborne nitrate. Similar source regions, along with Northeastern Madhya Pradesh were identified for
sulfate. 相似文献
158.
159.
Joanna Święta-Musznicka Małgorzata Latałowa Józef Szmeja Monika Badura 《Journal of Paleolimnology》2011,45(3):369-383
Large numbers of sub-fossil remains of the aquatic fern Salvinia natans (L.) All. have been found in several early medieval sites in Gdańsk, N. Poland. This record indicates a population expansion
of this species around 7th–8th century A.D., similar to the recently observed rapid spread and high population dynamics of
S. natans in northern Poland, which recent studies have attributed to climate warming. Our results suggest that in the Vistula deltaic
area the S. natans expansion in the Early Middle Ages (7th–8th century A.D.) was similarly stimulated by climate warming, while its subsequent
decline was mainly due to climate cooling, especially during the Little Ice Age. Warmer winters and springs and a longer growing
season seem to be the most important factors forcing the expansion of S. natans in medieval times. According to our data, the co-occurrence of S. natans with other aquatic plant species was similar in both the medieval and present-day vegetation. Also, the high density of S. natans in the medieval population caused impoverishment of the local ecosystems in a way that has been observed in recent water
bodies affected by invasive pleustophytes (free-floating plants). 相似文献
160.