排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
Faggioni Osvaldo Beverini Nicolò Carmisciano Cosmo Giori Italiano 《Marine Geophysical Researches》2001,22(2):63-79
We show the results obtained by means of a seabed reduction technique on the intensity of geomagnetic anomaly fields applied
to a synthetic case and then to the real case of a geomagnetic survey of eastern Ligurian Sea (Italy). The eastern Ligurian
Sea has very intense short waves anomaly fields and a sea bed that varies greatly in depth. As a result the geomagnetic space
signal is characterized by a very large spectral content; in these conditions it is not possible to obtain a full sampled
marine survey and vertical continuation analytic procedures and standard numerical bottom reduction based on a single vertical
incremental parameter, whichever is applicable, fails to give accurate results. The present technique, which has been fine-tuned
over 4 years of experimentation in environmental researchs, aims to provide a simple and efficient means to reduce the distortion
of geomagnetic anomalies field caused by the variation of distance between survey plane and magnetic outcrop source position.
The compensation procedure is based on evaluation, by comparison of two measurements carried out at different altitudes, of
the mean vertical increment typical of each anomaly field principal frequency component bands. The component anomaly fields
are then corrected by application of the corresponding vertical increments and lastly, the anomaly geomagnetic field reduced
to the sea-bed is computed as Inverse Fourier Transform of a spectrum built as synthesis of the component anomaly fields'
spectra. The results obtained have shown a notable increase in definition of anomaly field intensity without the production
of appreciable distortions or false geomagnetic echoes.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
2.
Franco Mantovani Francisco Javier Gracia Pietro Domenico de Cosmo Andrea Suma 《Landslides》2010,7(1):69-74
This paper presents the preliminary results of a geomorphological survey of the Olvera area (Cadiz province, Betic Ranges,
Spain) and the use of the Geographic Information System (GIS) Open Source (OS) software plus Database Management System (DBMS)
for making available and distributing the landslide data over the Web. In the geomorphologic survey, different landforms have
been identified in the area, including structural, anthropogenic, fluvial, karst, and slope forms. In particular, the majority
of the slope forms are complex (from topple to rotational slides and falls), but there are also minor forms like debris flows
and mudslides. To manage geomorphological data, an Open Source GIS was used, which contained the following components: QuantumGIS,
System for Automated Geoscientific Analyses (SAGA), GIS and Geographic Resources Analysis Support System (GRASS), GIS for
Digital Elevation Model (DEM) generation. A key aim was to make the project-derived data available over the Web. This was
achieved using MapServer which allows for the representation of the derived geospatial data with pMapper providing the graphical
Web interface. Our study highlights the process dynamics of run-off erosion in Olvera derived through the use of advanced
computer-based mapping tools. The resulting map products and interpretations are available via the Internet. To date, derivative
maps have been produced to improve maintenance of roads and transport and of the construction of new infrastructure. 相似文献
3.
Enrico Lorenzini Claudio Bombardelli Mario Cosmo Martin Harwit David Leisawitz Rodger Farley Stephen Rinehart David Quinn David Miller 《Astrophysics and Space Science》2006,302(1-4):225-239
Through the continuing development of improved detectors and detector arrays, far-infrared/submillimeter astronomical space
missions have had enormous successes in recent years. Despite these advances, the diffraction-limited angular resolving power
has remained virtually constant. The advent of telescopes with apertures of several meters will improve this capability, but
will still leave image resolution many orders of magnitude poorer than in most other spectral ranges. Here we point out that
the only foreseeable way to improve image quality to rival that of modern optical telescopes will be with interferometers
whose light collectors are connected by tethers. After making the scientific case for high spatial resolution far-infrared/submillimeter
imaging and the use of interferometry as the most immediate way of producing results, we discuss recent advances in dynamic
analysis and control of tethered formations, and argue that the further development and testing of tethers in space is a first
step toward providing improved far-infrared/submillimeter angular resolution and astronomical image quality. 相似文献
4.
Clive Oppenheimer Andy Orchard Markus Stoffel Timothy P. Newfield Sébastien Guillet Christophe Corona Michael Sigl Nicola Di Cosmo Ulf Büntgen 《Climatic change》2018,147(3-4):369-381
The Eldgjá lava flood is considered Iceland’s largest volcanic eruption of the Common Era. While it is well established that it occurred after the Settlement of Iceland (circa 874 CE), the date of this great event has remained uncertain. This has hampered investigation of the eruption’s impacts, if any, on climate and society. Here, we use high-temporal resolution glaciochemical records from Greenland to show that the eruption began in spring 939 CE and continued, at least episodically, until at least autumn 940 CE. Contemporary chronicles identify the spread of a remarkable haze in 939 CE, and tree ring-based reconstructions reveal pronounced northern hemisphere summer cooling in 940 CE, consistent with the eruption’s high yield of sulphur to the atmosphere. Consecutive severe winters and privations may also be associated with climatic effects of the volcanic aerosol veil. Iceland’s formal conversion to Christianity dates to 999/1000 CE, within two generations or so of the Eldgjá eruption. The end of the pagan pantheon is foretold in Iceland’s renowned medieval poem, V?luspá (‘the prophecy of the seeress’). Several lines of the poem describe dramatic eruptive activity and attendant meteorological effects in an allusion to the fiery terminus of the pagan gods. We suggest that they draw on first-hand experiences of the Eldgjá eruption and that this retrospection of harrowing volcanic events in the poem was intentional, with the purpose of stimulating Iceland’s Christianisation over the latter half of the tenth century. 相似文献
5.
Flood frequency under changing climate in the upper Kafue River basin, southern Africa: a large scale hydrological model application 总被引:1,自引:0,他引:1
Cosmo Ngongondo Lu Li Lebing Gong Chong-Yu Xu Berhanu F. Alemaw 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(8):1883-1898
The projected impacts of climate change and variability on floods in the southern Africa has not been well studied despite the threat they pose to human life and property. In this study, the potential impacts of climate change on floods in the upper Kafue River basin, a major tributary of the Zambezi River in southern Africa, were investigated. Catchment hydrography was delineated using the Hydro1k at a spatial resolution of 1 km. The daily global hydrological model WASMOD-D model was calibrated and validated during 1971–1986 and 1987–2001 with the simple-split sample test and during 1971–1980 and 1981–1990 with the differential split sample test, against observed discharge at Machiya gauging station. Predicted discharge for 2021–2050 and 2071–2100 were obtained by forcing the calibrated WASMOD-D with outputs from three GCMs (ECHAM, CMCC3 and IPSL) under the IPCC’s SRES A2 and B1 scenarios. The three GCMs derived daily discharges were combined by assigning a weight to each of them according to their skills to reproduce the daily discharge. The two calibration and validation tests suggested that model performance based on evaluation criteria including the Nash–Sutcliffe coefficient, Pearson’s correlation coefficient (r), Percent Bias and R 2 was satisfactory. Flood frequency analysis for the reference period (1960–1990) and two future time slices and climate change scenarios was performed using the peak over threshold analysis. The magnitude of flood peaks was shown to follow generalised Pareto distribution. The simulated floods in the scenario periods showed considerable departures from the reference period. In general, flood events increased during both scenario periods with 2021–2050 showing larger change. The approach in our study has a strong potential for similar assessments in other data scarce regions. 相似文献
6.
Flooding scenarios due to land subsidence and sea‐level rise: a case study for Lipari Island (Italy) 下载免费PDF全文
Marco Anzidei Alessandro Bosman Roberto Carluccio Daniele Casalbore Francesca D'Ajello Caracciolo Alessandra Esposito Iacopo Nicolosi Grazia Pietrantonio Antonio Vecchio Cosmo Carmisciano Massimo Chiappini Francesco Latino Chiocci Filippo Muccini Vincenzo Sepe 《地学学报》2017,29(1):44-51
Archaeological and instrumental data indicate that the southern sector of the volcanic island of Lipari has been subsiding for the last 2100 years due to isostatic and tectonic factors, at variable rates of up to ~11 mm a?1. Based on this data, a detailed marine flooding scenario for 2100 AD is provided for the bay of Marina Lunga in the eastern part of the island from (1) an ultra‐high‐resolution Digital Terrain and Marine Model (DTMM) generated from multibeam bathymetry (MB) and Unmanned Aerial Vehicles (UAV), (2) the rate of land subsidence from Global Positioning System (GPS) data and (3) the regional sea‐level projections of the International Panel on Climate Change (IPCC). When land subsidence is considered, the upper bound of sea‐level rise is estimated at 1.36 m and 1.60 m for RCP4.5 and RCP8.5 climate change scenarios, respectively. Here, we show the expected impact of marine flooding at Lipari for the next 85 years and discuss the hazard implications for the population living along the shore. 相似文献
7.
Regional frequency analysis of rainfall extremes in Southern Malawi using the index rainfall and L-moments approaches 总被引:3,自引:1,他引:2
Cosmo S. Ngongondo Chong-Yu Xu Lena M. Tallaksen Berhanu Alemaw Tobias Chirwa 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(7):939-955
Rainfall extremes often result in the occurrence of flood events with associated loss of life and infrastructure in Malawi.
However, an understanding of the frequency of occurrence of such extreme events either for design or disaster planning purposes
is often limited by data availability at the desired temporal and spatial scales. Regionalisation, which involves “trading
time for space” by pooling together observations for stations with similar behavior, is an alternative approach for more accurate
determination of extreme events even at ungauged areas or sites with short records. In this study, regional frequency analysis
of rainfall extremes in Southern Malawi, large parts of which are flood prone, was undertaken. Observed 1-, 3-, 5- and 7-day
annual maximum rainfall series for the period 1978–2007 at 23 selected rainfall stations in Southern Malawi were analysed.
Cluster analysis using scaled at-site characteristics was used to determine homogeneous rainfall regions. L-moments were applied
to derive regional index rainfall quantiles. The procedure also validated the three rainfall regions identified through homogeneity
and heterogeneity tests based on Monte Carlo simulations with regional average L-moment ratios fitted to the Kappa distribution.
Based on assessments of the accuracy of the derived index rainfall quantiles, it was concluded that the performance of this
regional approach was satisfactory when validated for sites not included in the sample data. The study provides an estimate
of the regional characteristics of rainfall extremes that can be useful in among others flood mitigation and engineering design. 相似文献
8.
L. Golub E. DeLuca G. Austin J. Bookbinder D. Caldwell P. Cheimets J. Cirtain M. Cosmo P. Reid A. Sette M. Weber T. Sakao R. Kano K. Shibasaki H. Hara S. Tsuneta K. Kumagai T. Tamura M. Shimojo J. McCracken J. Carpenter H. Haight R. Siler E. Wright J. Tucker H. Rutledge M. Barbera G. Peres S. Varisco 《Solar physics》2007,243(1):63-86
The X-ray Telescope (XRT) of the Hinode mission provides an unprecedented combination of spatial and temporal resolution in solar coronal studies. The high sensitivity
and broad dynamic range of XRT, coupled with the spacecraft’s onboard memory capacity and the planned downlink capability
will permit a broad range of coronal studies over an extended period of time, for targets ranging from quiet Sun to X-flares.
This paper discusses in detail the design, calibration, and measured performance of the XRT instrument up to the focal plane.
The CCD camera and data handling are discussed separately in a companion paper. 相似文献
9.
Evaluation of spatial and temporal characteristics of rainfall in Malawi: a case of data scarce region 总被引:1,自引:1,他引:0
Cosmo Ngongondo Chong-Yu Xu Lars Gottschalk Berhanu Alemaw 《Theoretical and Applied Climatology》2011,106(1-2):79-93
This paper presents the methods, procedure and results in studying spatial and temporal characteristics of rainfall in Malawi, a data scarce region, between 1960 and 2006. Rainfall variables and indicators from rainfall readings at 42 stations in Malawi, excluding Lake Malawi, were analysed at monthly, seasonal and annual scales. In the study, the data were firstly subjected to quality checks through the cumulative deviations test and the standard normal homogeneity test. Spatial rainfall variability was investigated using the spatial correlation function. Temporal trends were analysed using Mann?CKendall and linear regression methods. Heterogeneity of monthly rainfall was investigated using the precipitation concentration index (PCI). Finally, inter-annual and intra-annual rainfall variability were tested using normalized precipitation anomaly series of annual rainfall series (|AR|) and the PCI (|APCI|), respectively. The results showed that (1) most stations revealed statistically non-significant decreasing rainfall trends for annual, seasonal, monthly and the individual months from March to December at the 5% significance level. The months of January and February (the highest rainfall months), however, had overall positive but statistically non-significant trends countrywide, suggesting more concentration of the seasonal rainfall around these months. (2) Spatial analysis results showed a complex rainfall pattern countrywide with annual mean of 1,095?mm centred to the south of the country and mean inter-annual variability of 26%. (3) Spatial correlation amongst stations was highest only within the first 20?km, typical of areas with strong small-scale climatic influence. (4) The country was further characterised by unstable monthly rainfall regimes, with all PCIs more than 10. (5) An increase in inter-annual rainfall variability was found. 相似文献
10.