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41.
A. A. Hakobyan A. R. Petrosian G. A. Mamon B. McLean D. Kunth M. Turatto E. Cappelaro F. Mannucci R. J. Allen N. Panagia M. Della Valle 《Astrophysics》2009,52(1):40-53
The determination of the supernova (SN) rate is based not only on the number of detected events, but also on the properties
of the parent galaxy population. This is the first paper of a series aimed at obtaining new, refined, SN rates from a set
of five SN surveys, by making use of a joint analysis of near-infrared (NIR) data. We describe the properties of the 3838
galaxies that were monitored for SNe events, including newly determined morphologies and their DENIS, and POSS-II/UKST I,
2MASS and DENIS J and Ks and 2MASS H magnitudes. We have compared 2MASS, DENIS and POSS-II/UKST IJK magnitudes in order to find possible systematic
photometric shifts in the measurements. The DENIS and POSS-II/UKST I band magnitudes show large discrepancies (mean absolute
difference of 0.4 mag.), mostly due to different spectral responses of the two instruments, with an important contribution
(0.33 mag rms) from the large uncertainties in the photometric calibration of the POSS-II and UKST photographic plates. In
the other wavebands, the limiting near infrared magnitude, morphology, and inclination of the galaxies are the most influential
factors which affect the determination of photometry of the galaxies. Nevertheless, no significant systematic differences
have been found between any pair of NIR magnitude measurements, except for a few percent of galaxies showing large discrepancies.
This allows us to combine DENIS and 2MASS data for the J and Ks filters.
Published in Astrofizika, Vol. 52, No. 1, pp. 47–62 (Februay 2009). 相似文献
42.
Recent global-scale analyses of the CMIP3 model projections for the twenty-first century indicate a strong, coherent decreased
precipitation response over Central America and the Intra-America Seas region. We explore this regional response and examine
the models’ skill in representing present-day climate over this region. For much of Central America, the annual cycle of precipitation
is characterized by a rainy season that extends from May to October with a period of reduced precipitation in July and August
called the mid-summer drought. A comparison of the climate of the twentieth century simulations (20c3m) with observations
over the period 1961–1990 shows that nearly all models underestimate precipitation over Central America, due in part to an
underestimation of sea surface temperatures over the tropical North Atlantic and an excessively smooth representation of regional
topographical features. However, many of the models capture the mid-summer drought. Differences between the A1B scenario (2061–2090)
and 20c3m (1961–1990) simulations show decreased precipitation in the future climate scenario, mostly in June and July, just
before and during the onset of the mid-summer drought. We thus hypothesize that the simulated twenty-first century drying
over Central America represents an early onset and intensification of the mid-summer drought. An analysis of circulation changes
indicates that the westward expansion and intensification of the North Atlantic subtropical high associated with the mid-summer
drought occurs earlier in the A1B simulations, along with stronger low-level easterlies. The eastern Pacific inter-tropical
convergence zone is also located further southward in the scenario simulations. There are some indications that these changes
could be forced by ENSO-like warming of the tropical eastern Pacific and increased land–ocean heating contrasts over the North
American continent. 相似文献
43.
In order to define adequate prevention measures and to manage landslide emergencies, real-time monitoring is required. This
paper presents two different applications of the remote sensing technique: the ground-based synthetic aperture radar interferometry,
here proposed as a monitoring and early warning support for slope instability. Data acquisitions carried out through a ground-based
synthetic aperture radar interferometer, operating in Ku band, installed in front of the observed slopes, are discussed. Two case studies, based on the use of the same apparatus
(formerly developed by the Joint Research Center of the European Commission and by Ellegi-LiSALab srl), are reported: the
first one concerns the monitoring of a large landslide, named Ruinon (Valfurva, Italy). The second one deals with the monitoring
of the NW unstable slope in the Stromboli island aimed to implementing an early warning system. Acquired interferometric data
are processed to provide displacements and velocity maps of the monitored area. The monitoring services ongoing on the Ruinon
landslide and on Stromboli demonstrate the capability of this technique to operate in different operative settings (i.e.,
different phenomena and geological framework) and for different aims (monitoring for prevention, early warning, and emergency
assessment). This methodology has also been proved by national and regional authorities of civil protection in order to provide
a real-time monitoring for emergency management. 相似文献
44.
Daily output from the PRUDENCE ensemble of regional climate simulations for the end of the twentieth and twenty-first centuries over Europe is used to show that the increasing intensity of the most damaging summer heat waves over Central Europe is mostly due to higher base summer temperatures. In this context, base temperature is defined as the mean of the seasonal cycle component for those calendar days when regional heat waves occur and is close, albeit not identical, to the mean temperature for July–August. Although 36–47% of future Central Europe July and August days at the end of the twenty-first century are projected to be extreme according to the present day climatology, specific changes in deseasonalized heat wave anomalies are projected to be relatively small. Instead, changes in summer base temperatures appear much larger, clearly identifiable and of the same order of magnitude as changes in the whole magnitude of heat waves. Our results bear important consequences for the predictability of central European heat wave intensity under global warming conditions. 相似文献
45.
Resolution effects on regional climate model simulations of seasonal precipitation over Europe 总被引:5,自引:2,他引:3
We analyze a set of nine regional climate model simulations for the period 1961–2000 performed at 25 and 50 km horizontal
grid spacing over a European domain in order to determine the effects of horizontal resolution on the simulation of precipitation.
All of the models represent the seasonal mean spatial patterns and amount of precipitation fairly well. Most models exhibit
a tendency to over-predict precipitation, resulting in a domain-average total bias for the ensemble mean of about 20% in winter
(DJF) and less than 10% in summer (JJA) at both resolutions, although this bias could be artificially enhanced by the lack
of a gauge correction in the observations. A majority of the models show increased precipitation at 25 km relative to 50 km
over the oceans and inland seas in DJF, JJA, and ANN (annual average), although the response is strongest during JJA. The
ratio of convective precipitation to total precipitation decreases over land for most models at 25 km. In addition, there
is an increase in interannual variability in many of the models at 25 km grid spacing. Comparison with gridded observations
indicates that a majority of models show improved skill in simulating both the spatial pattern and temporal evolution of precipitation
at 25 km compared to 50 km during the summer months, but not in winter or on an annual mean basis. Model skill at higher resolution
in simulating the spatial and temporal character of seasonal precipitation is found especially for Great Britain. This geographic
dependence of the increased skill suggests that observed data of sufficient density are necessary to capture fine-scale climate
signals. As climate models increase their horizontal resolution, it is thus a key priority to produce high quality fine scale
observations for model evaluation. 相似文献
46.
Does the model regional bias affect the projected regional climate change? An analysis of global model projections 总被引:2,自引:0,他引:2
An analysis is presented of the dependence of the regional temperature and precipitation change signal on systematic regional biases in global climate change projections. The CMIP3 multi-model ensemble is analyzed over 26 land regions and for the A1B greenhouse gas emission scenario. For temperature, the model regional bias has a negligible effect on the projected regional change. For precipitation, a significant correlation between change and bias is found in about 30% of the seasonal/regional cases analyzed, covering a wide range of different climate regimes. For these cases, a performance-based selection of models in producing climate change scenarios can affect the resulting change estimate, and it is noted that a minimum of four to five models is needed to obtain robust precipitation change estimates. In a number of cases, models with largely different precipitation biases can still produce changes of consistent sign. Overall, it is assessed that in the present generation of models the regional bias does not appear to be a dominant factor in determining the simulated regional change in the majority of cases. 相似文献
47.
48.
区域气候模式对温室效应引起的中国地区气候变化的数值模拟 总被引:93,自引:9,他引:93
利用基于 RegCM2的区域气候模式并单向嵌套澳大利亚 CSIRO R21L9全球海-气耦合模式,进行了温室气体二氧化碳浓度倍增对中国气候变化影响的数值试验研究。控制试验结果表明:区域模式由于具有较高的分辨率,因而对中国区域地面气温和降水的模拟效果较全球模式有了较大提高;模式对 2×CO2敏感性试验结果表明了在 CO2浓度倍增情况下,由于温室效应,中国区域的地面气温将有明显升高,降水也将呈增加趋势。 相似文献
49.
On the application of SAR interferometry to geomorphological studies: estimation of landform attributes and mass movements 总被引:9,自引:0,他引:9
Filippo Catani Paolo Farina Sandro Moretti Giovanni Nico Tazio Strozzi 《Geomorphology》2005,66(1-4):119
This paper presents two examples of application of Synthetic Aperture Radar (SAR) interferometry (InSAR) to typical geomorphological problems. The principles of InSAR are introduced, taking care to clarify the limits and the potential of this technique for geomorphological studies. The application of InSAR to the quantification of landform attributes such as the slope and to the estimation of landform variations is investigated. Two case studies are presented. A first case study focuses on the problem of measuring landform attributes by interferometric SAR data. The interferometric result is compared with the corresponding one obtained by a Digital Elevation Model (DEM). In the second case study, the use of InSAR for the estimation of landform variations caused by a landslide is detailed. 相似文献
50.
Observations of physical effects from tsunamis of December 30, 2002 at Stromboli volcano, southern Italy 总被引:1,自引:0,他引:1
Stefano Tinti Alessandra Maramai Alberto Armigliato Laura Graziani Anna Manucci Gianluca Pagnoni Filippo Zaniboni 《Bulletin of Volcanology》2006,68(5):450-461
On December 30, 2002, following an intense period of activity of Stromboli volcano (south Tyrrhenian Sea, Italy), complex mass failures occurred on the northwest slope of the mountain which also involved the underwater portion of the volcanic edifice for a total volume of about 2–3×107 m3. Two main landslides occurred within a time separation of 7 min, and both set tsunami waves in motion that hit the coasts of Stromboli causing injuries to three people and severe damage to buildings and structures. The tsunamis also caused damage on the island of Panarea, some 20 km to the SSE from the source. They were observed all over the Aeolian archipelago, at the island of Ustica to the west, along the northern Sicily coasts to the south as well as along the Tyrrhenian coasts of Calabria to the east and in Campania to the north. This paper presents field observations that were made in the days and weeks immediately following the events. The results of the quantitative investigations undertaken in the most affected places, namely along the coasts of Stromboli and on the island of Panarea, are reported in order to highlight the dynamics of the attacking waves and their impact on the physical environment, on the coastal structures and on the coastal residential zone. In Stromboli, the tsunami waves were most violent along the northern and northeastern coastal belt between Punta Frontone and the village of Scari, with maximum runup heights of about 11 m measured on the beach of Spiaggia Longa. Measured runups were observed to decay rapidly with distance from the source, typical of tsunami waves generated by limited-area sources such as landslides. 相似文献