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111.
Yoo-Geun Ham Michele M. Rienecker Max J. Suarez Yury Vikhliaev Bin Zhao Jelena Marshak Guillaume Vernieres Siegfried D. Schubert 《Climate Dynamics》2014,42(1-2):1-20
A suite of decadal predictions has been conducted with the NASA Global Modeling and Assimilation Office’s (GMAO’s) GEOS-5 Atmosphere–Ocean general circulation model. The hind casts are initialized every December 1st from 1959 to 2010, following the CMIP5 experimental protocol for decadal predictions. The initial conditions are from a multi-variate ensemble optimal interpolation ocean and sea-ice reanalysis, and from GMAO’s atmospheric reanalysis, the modern-era retrospective analysis for research and applications. The mean forecast skill of a three-member-ensemble is compared to that of an experiment without initialization but also forced with observed greenhouse gases. The results show that initialization increases the forecast skill of North Atlantic sea surface temperature compared to the uninitialized runs, with the increase in skill maintained for almost a decade over the subtropical and mid-latitude Atlantic. On the other hand, the initialization reduces the skill in predicting the warming trend over some regions outside the Atlantic. The annual-mean atlantic meridional overturning circulation index, which is defined here as the maximum of the zonally-integrated overturning stream function at mid-latitude, is predictable up to a 4-year lead time, consistent with the predictable signal in upper ocean heat content over the North Atlantic. While the 6- to 9-year forecast skill measured by mean squared skill score shows 50 % improvement in the upper ocean heat content over the subtropical and mid-latitude Atlantic, prediction skill is relatively low in the subpolar gyre. This low skill is due in part to features in the spatial pattern of the dominant simulated decadal mode in upper ocean heat content over this region that differ from observations. An analysis of the large-scale temperature budget shows that this is the result of a model bias, implying that realistic simulation of the climatological fields is crucial for skillful decadal forecasts. 相似文献
112.
Runoff and nutrient transport by rivers were analysed in the Northern Adriatic continental shelf, in order to evaluate their interannual and multidecal variability, as well as their current contribution to determine freshwater and nutrient budgets in this marine region. During the years 2004-2007, the runoff in the basin (34.1-64.6 km3 yr−1) was highly imbalanced, being 84% of freshwater discharged along the western coast, because of the contributions of Po, Adige and Brenta rivers. In the northern and eastern sections of the coast, freshwater discharge by rivers was less important (10 and 6%, respectively), but not negligible in determining the oceanographic properties at sub-regional scales. The oscillations of the transport of biogenic elements (124-262×103 t N yr−1 for TN, 72-136×103 t N yr−1 for DIN, 4.5-11.1×103t P yr−1 for TP, 2.2-3.5×103 t P yr−1 for PO4 and 104-196×103 t Si yr−1 for SiO2) were strictly dependant to the differences in the annual runoff. A strong excess of N load in comparison to P load characterised all rivers, both in inorganic nutrient (DIN/PO4=37-418) and total (TN/TP=48-208) pools, particularly in the northern and eastern areas of the basin.The annual runoff showed significant oscillations for Po on multidecadal time scale, whereas a general decrease (−33%) was observed for the other N Adriatic rivers as the recent discharges were compared to those before the 1980s. During the dry years 2005-2007, a strong reduction of river water flows and nutrient loads was experienced by the N Adriatic ecosystem with respect to years characterised by medium-high regimes. An increased frequency of similar drought periods, due to ongoing climate changes or to a larger human usage of continental waters, would be easily able to significantly change the biogeochemistry of this basin. 相似文献
113.
Paola Monaco Filippo Santucci de Magistris Salvatore Grasso Silvano Marchetti Michele Maugeri Gianfranco Totani 《Bulletin of Earthquake Engineering》2011,9(1):231-261
This paper describes a case-history of liquefaction occurred near the village of Vittorito after the April 6, 2009 L’Aquila
earthquake (moment magnitude Mw = 6.3), approximately 45 km far from the epicentre. In the document, first, an estimation of the seismic motion in the area
has been made. Thereafter, the performed geotechnical investigation is described, followed by the application of some fast
assessment criteria for the occurrence of liquefaction, recently proposed by the new Italian Building Code. A careful assessment
of all the parameters involved in conventional Seed and Idriss (1971) liquefaction analyses is considered. The cyclic resistance ratio CRR is evaluated by cone penetration tests CPT and by in
situ seismic dilatometer tests SMDT; in the latter case CRR is evaluated by different empirical correlations with shear wave
velocity Vs and horizontal stress index KD. Analytical data confirmed the observed occurrence of the liquefaction in Vittorito, even if the acceleration field in the
area, produced by the L’Aquila earthquake, was very low. 相似文献
114.
Luciano Telesca Michele Lovallo Márta Marótiné Kiszely László Toth 《Acta Geophysica》2011,59(5):858-871
The Fisher-Shannon information (FS) plane, defined by the Fisher information measure (FIM), and the Shannon entropy power,
N
x
, is a robust tool for investigating the complex dynamics of time series. In the FS plane, earthquakes and quarry blasts measured
in Vértes Hills (Hungary) are significantly discriminated from each other. Furthermore, the results of the receiving-operating
characteristics (ROC) analysis reveal that FIM is a classifier more efficient than N
x
in discriminating earthquakes from quarry blasts. 相似文献
115.
Gerardo Herrera Davide Notti Juan Carlos Garc��a-Davalillo Oscar Mora Geraint Cooksley M��nica S��nchez Alain Arnaud Michele Crosetto 《Landslides》2011,8(2):195-206
This paper describes the use of the Stable Point Network technique, a Persistent Scatterer Interferometry SAR technique, for
the analysis of the Portalet landslide area (Central Pyrenees, Spain). For this purpose, different SAR datasets acquired by
ERS-1, ERS-2, ENVISAT and TerraSAR-X satellites have been analysed. The use of different SAR images acquired by satellite
radar sensors operating at different microwave lengths has allowed for a comparative assessment and illustration of the advantages
and disadvantages of these satellites for landslide detection and monitoring. In the introduction, differential interferometry
and the study area are briefly described. Then the specifics of the SPN processing and the results of the different datasets
are described and compared. In Analysis of the results: the Portalet landslide area, the Portalet landslide area is introduced
and the radar displacement measurements are analysed with available geo-information data. Additionally, X-band measurements
are compared with those gathered by a ground-based SAR for a previous project. Finally, the most relevant conclusions of this
work are discussed. 相似文献
116.
Daniele Spiga Gianpiero Tagliaferri Paolo Soffitta Oberto Citterio Stefano Basso Ronaldo Bellazzini Alessandro Brez Wolfgang Burkert Vadim Burwitz Enrico Costa Luca de Ruvo Ettore Del Monte Sergio Fabiani Gisela Hartner Benedikt Menz Massimo Minuti Fabio Muleri Giovanni Pareschi Michele Pinchera Alda Rubini Carmelo Sgrò Gloria Spandre 《Experimental Astronomy》2014,37(1):37-53
The Joint European X-ray Telescope (JET-X) was the core instrument of the Russian Spectrum-X- γ space observatory. It consisted of two identical soft X-ray (0.3–10 keV) telescopes with focusing optical modules having a measured angular resolution of nearly 15 arcsec. Soon after the payload completion, the mission was cancelled and the two optical flight modules (FM) were brought to the Brera Astronomical Observatory where they had been manufactured. After 16 years of storage, we have utilized the JET-X FM2 to test at the PANTER X-ray facility a prototype of a novel X-ray polarimetric telescope, using a Gas Pixel Detector (GPD) with polarimetric capabilities in the focal plane of the FM2. The GPD was developed by a collaboration between INFN-Pisa and INAF-IAPS. In the first phase of the test campaign, we have re-tested the FM2 at PANTER to have an up-to-date characterization in terms of angular resolution and effective area, while in the second part of the test the GPD has been placed in the focal plane of the FM2. In this paper we report the results of the tests of the sole FM2, using an unpolarized X-ray source, comparing the results with the calibration done in 1996. 相似文献
117.
118.
Richard M. McDermid Roland Bacon Harald Kuntschner Eric Emsellem Kristen L. Shapiro Martin Bureau Michele Cappellari Roger L. Davies Jesús Falcn-Barroso Davor Krajnovi Reynier F. Peletier Marc Sarzi Tim de Zeeuw 《New Astronomy Reviews》2006,49(10-12):521
We summarise the results and achievements of integral-field spectroscopy of early-type galaxies, observed as part of a survey using both the SAURON and OASIS spectrographs. From the perspective of integral-field spectroscopy, these otherwise smooth and featureless objects show a wealth of structure, both in their stellar kinematics and populations. We focus on the stellar content, and examine properties on both kiloparsec scales with SAURON, and scales of 100’s of parsecs with OASIS. These complementary studies reveal two types of kinematically distinct components (KDCs), differing primarily in their intrinsic sizes. In previous studies, KDCs and their host galaxies have generally been found to be unremarkable in other aspects. We show that large KDCs, typical of the well-studied cases, indeed show little or no age differences with their host galaxy. The KDCs detected with the higher spatial-resolution of OASIS are intrinsically smaller and include, in contrast, a significant fraction of young stars. We speculate on the relationship between KDCs and their host galaxies, and the implications for young populations in early-type galaxies. 相似文献
119.
120.