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41.
The atmospheres and circumstellar envelopes of AGB stars are characterized by complex physical phenomena like shock waves
caused by stellar pulsation or formation of molecules and dust which often lead to a heavy mass loss and have a strong influence
on IR properties as observed by ISO. To allow a physical interpretation of various observations we have constructed improved
dynamical model atmospheres of long-period variables. In this contribution we mainly investigate the dependence of the atmospheric
structure and its variability on stellar pulsation, molecular opacities and time-dependent dust formation. IR spectra resulting
from our models are discussed in detail by Loidl et al. (1997b) and compared to ISO-SWS spectra obtained by Hron et al. (1997).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
42.
Darren Ruddell Sharon L. Harlan Susanne Grossman-Clarke Gerardo Chowell 《Climatic change》2012,111(3-4):581-607
Understanding public perceptions of climate is critical for developing an effective strategy to mitigate the effects of human activity on the natural environment and reduce human vulnerability to the impacts of climate change. While recent climate assessments document change among various physical systems (e.g., increased temperature, sea level rise, shrinking glaciers), environmental perceptions are relatively under-researched despite the fact that there is growing skepticism and disconnect between climate science and public opinion. This study utilizes a socio-ecological research framework to investigate how public perceptions compared with environmental conditions in one urban center. Specifically, air temperature during an extreme heat event was examined as one characteristic of environmental conditions by relating simulations from the Weather Research and Forecast (WRF) atmospheric model with self-reported perceptions of regional and neighborhood temperatures from a social survey of Phoenix, AZ (USA) metropolitan area residents. Results indicate that: 1) human exposure to high temperatures varies substantially throughout metropolitan Phoenix; 2) public perceptions of temperature are more strongly correlated with proximate environmental conditions than with distal conditions; and 3) perceptions of temperature are related to social characteristics and situational variables. The social constructionist paradigm explains public perceptions at the regional scale, while experience governs attitude formation at the neighborhood scale. 相似文献
43.
Sebastian Schubert Susanne Grossman-Clarke Alberto Martilli 《Boundary-Layer Meteorology》2012,145(3):439-468
We develop a double-canyon radiation scheme (DCEP) for urban canopy models embedded in mesoscale numerical models based on the Building Effect Parametrization (BEP). The new scheme calculates the incoming and outgoing longwave and shortwave radiation for roof, wall and ground surfaces for an urban street canyon characterized by its street and building width, canyon length, and the building height distribution. The scheme introduces the radiative interaction of two neighbouring urban canyons allowing the full inclusion of roofs into the radiation exchange both inside the canyon and with the sky. In contrast to BEP, we also treat direct and diffuse shortwave radiation from the sky independently, thus allowing calculation of the effective parameters representing the urban diffuse and direct shortwave radiation budget inside the mesoscale model. Furthermore, we close the energy balance of incoming longwave and diffuse shortwave radiation from the sky, so that the new scheme is physically more consistent than the BEP scheme. Sensitivity tests show that these modifications are important for urban regions with a large variety of building heights. The evaluation against data from the Basel Urban Boundary Layer Experiment indicates a good performance of the DCEP when coupled with the regional weather and climate model COSMO-CLM. 相似文献
44.
Susanne Moser 《Climatic change》2009,95(1-2):11-21
Decision support has become a popular concept, especially in the context of climate change. Government agencies and researchers increasingly recognize that they should provide it, and resource managers and policy-makers increasingly need and demand it. This demand will only grow as climate change progresses. Those who will attempt to meet this growing demand will need to demonstrate “effectiveness”. This editorial raises a number of critical questions that need to be answered in the course of evaluating whether decision support is effective. The answers, if carefully considered early on, may help to design processes that may in fact produce more useable products, facilitate their use, and ultimately create intended and desirable outcomes. 相似文献
45.
C. Sigismondi D. W. Dunham K. Guhl S. Andersson H. Bode O. Canales P. Colona O. Farago M. Fernández-Ocaña A. Gabel M. Haupt C. Herold R. Nugent P. Oliva M. Patel C. Perello W. Rothe J. Rovira T. Schaefer C. Schnabel D. Schwartz A. Selva W. Strickling A. Tegtmeier C. Tegtmeier B. Thome W. H. Warren 《Solar physics》2009,258(2):191-202
In the annular or total eclipses of 3 October 2005, 29 March 2006, 22 September 2006, and 1 August 2008, observational campaigns
were organized to record the phenomenon of Baily’s beads. These campaigns were internationally coordinated through the International
Occultation Timing Association (IOTA) at both its American and European sections. From the stations in the northern and southern
zones of grazing eclipse, the eclipses have been recorded on video. Afterward, as many beads as possible have been identified
by analyzing the video data of each observing station. The atlas presented in this paper includes 598 data points, obtained
by 23 observers operating at 28 different observing stations. The atlas lists the geographic positions of the observing stations
and the observed time instants of disappearance or reappearance of beads, identified by an angle measured relative to the
Moon’s axis of rotation. The atlas will serve as a basis for determining the solar diameter.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
46.
Noble gas adsorption with and without mechanical stress: Not Martian signatures but fractionated air
Susanne P. SCHWENZER Siegfried HERRMANN Ulrich OTT 《Meteoritics & planetary science》2012,47(6):1049-1061
Abstract– Sample preparation, involving physical and chemical methods, is an unavoidable step in geochemical analysis. From a noble gas perspective, the two important effects are loss of sample gas and/or incorporation of air, which are significant sources of analytical artifacts. This article reports on the effects of sample exposure to laboratory air without mechanical influence and during sample grinding. The experiments include pure adsorption on terrestrial analog materials (gibbsite and olivine) and grinding of Martian meteorites. A consistent observation is the presence of an elementally fractionated air component in the samples studied. This is a critical form of terrestrial contamination in meteorites as it often mimics the heavy noble gas signatures of known extra‐terrestrial end‐members that are the basis of important conclusions about the origin and evolution of a meteorite. Although the effects of such contamination can be minimized by avoiding elaborate sample preparation protocols, caution should be exercised in interpreting the elemental ratios (Ar/Xe, Kr/Xe), especially in the low‐temperature step extractions. The experiments can also be transferred to the investigation of Martian meteorites with long terrestrial residence times, and to Mars, where the Mars Science Laboratory mission will be able to measure noble gas signatures in the current atmosphere and in rocks and soils collected on the surface in Gale crater. 相似文献
47.
Susanne Aalto 《Astrophysics and Space Science》2008,313(1-3):273-278
Molecular line emission is a useful tool for probing the highly obscured inner kpc of starburst galaxies and buried AGNs.
Molecular line ratios serve as diagnostic tools of the physical conditions of the gas—but also of its chemical properties.
Both provide important clues to the type and evolutionary stage of the nuclear activity. While CO emission remains the main
tracer for molecular distribution and dynamics, molecules such as HCN, HNC, HCO+, CN and HC3N are useful for probing the properties of the denser (n≳104 cm−3), star-forming gas. Here I discuss current views on how line emission from these species can be interpreted in luminous galaxies.
HNC, HCO+ and CN are all species that can be associated both with photon dominated regions (PDRs) in starbursts—as well as X-ray dominated
regions (XDRs) associated with AGN activity. HC3N line emission may identify galaxies where the starburst is in the early stage of its evolution. 相似文献
48.
Andrew Curtis Jayakrishnan Ajayakumar Eric Jefferis Susanne Mitchell 《International journal of geographical information science》2019,33(6):1224-1250
ABSTRACTThe importance of including a contextual underpinning to the spatial analysis of social data is gaining traction in the spatial science community. The challenge, though, is how to capture these data in a rigorous manner that is translational. One method that has shown promise in achieving this aim is the spatial video geonarrative (SVG), and in this paper we pose questions that advance the science of geonarratives through a case study of criminal ex-offenders. Eleven ex-offenders provided sketch maps and SVGs identifying high-crime areas of their community. Wordmapper software was used to map and classify the SVG content; its spatial filter extension was used for hot spot mapping with statistical significance tested using Monte Carlo simulations. Then, each subject’s sketch map and SVG were compared. Results reveal that SVGs consistently produce finer spatial-scale data and more locations of relevance than the sketch maps. SVGs also provide explanation of spatial-temporal processes and causal mechanisms linked to specific places, which are not evident in the sketch maps. SVG can be a rigorous translational method for collecting data on the geographic context of many phenomena. Therefore, this paper makes an important advance in understanding how environmentally immersive methods contribute to the understanding of geographic context. 相似文献
49.
Susanne Glaser Rolf König Dimitrios Ampatzidis Tobias Nilsson Robert Heinkelmann Frank Flechtner Harald Schuh 《Journal of Geodesy》2017,91(7):723-733
In this study, we assess the impact of two combination strategies, namely local ties (LT) and global ties (GT), on the datum realization of Global Terrestrial Reference Frames in view of the Global Geodetic Observing System requiring 1 mm-accuracy. Simulated Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data over a 7 year time span was used. The LT results show that the geodetic datum can be best transferred if the precision of the LT is at least 1 mm. Investigating different numbers of LT, the lack of co-located sites on the southern hemisphere is evidenced by differences of 9 mm in translation and rotation compared to the solution using all available LT. For the GT, the combination applying all Earth rotation parameters (ERP), such as pole coordinates and UT1-UTC, indicates that the rotation around the Z axis cannot be adequately transferred from VLBI to SLR within the combination. Applying exclusively the pole coordinates as GT, we show that the datum can be transferred with mm-accuracy within the combination. Furthermore, adding artificial stations in Tahiti and Nigeria to the current VLBI network results in an improvement in station positions by 13 and 12%, respectively, and in ERP by 17 and 11%, respectively. Extending to every day VLBI observations leads to 65% better ERP estimates compared to usual twice-weekly VLBI observations. 相似文献
50.
GPS code pseudorange measurements exhibit group delay variations at the transmitting and the receiving antenna. We calibrated C1 and P2 delay variations with respect to dual-frequency carrier phase observations and obtained nadir-dependent corrections for 32 satellites of the GPS constellation in early 2015 as well as elevation-dependent corrections for 13 receiving antenna models. The combined delay variations reach up to 1.0 m (3.3 ns) in the ionosphere-free linear combination for specific pairs of satellite and receiving antennas. Applying these corrections to the code measurements improves code/carrier single-frequency precise point positioning, ambiguity fixing based on the Melbourne–Wübbena linear combination, and determination of ionospheric total electron content. It also affects fractional cycle biases and differential code biases. 相似文献