To address the current data and understanding knowledge gap in landslide dam inventories related to geomorphological parameters, a new global-scale landslide dam dataset named River Augmented Global Landslide Dams (RAGLAD) was created. RAGLAD is a collection of landslide dam records from multiple data sources published in various languages and many of these records we have been able to precisely geolocate. In total, 779 landslide dam records were compiled from 34 countries/regions. The spatial distribution, time trend, triggers, and geomorphological characteristic of the landslides and catchments where landslide dams formed are summarized. The relationships between geomorphological characteristics for landslides that form river dams are discussed and compared with those of landslides more generally. Additionally, a potential threshold for landslide dam formation is proposed, based on the relationship of landslide volume to river width. Our findings from our analysis of the value of the use of additional fluvial datasets to augment the database parameters indicate that they can be applied as a reliable supplemental data source, when the landslide dam records were accurately and precisely geolocated, although location precision in smaller river catchment areas can result in some uncertainty at this scale. This newly collected and supplemented dataset will allow the analysis and development of new relationships between landslides located near rivers and their actual propensity to block those particular rivers based on their geomorphology.
We combine high-resolution observations of the dynamical behavior of small vortices (diameters ?5000 km) located at latitude 60°N on Jupiter with forward modeling, using the EPIC atmospheric model, to address two open questions: the dependence of the zonal winds with depth, and the strength of vortices that are too small to apply cloud tracking to their internal structure. The observed drift rates of the vortices can only be reproduced in the model when the zonal winds increase slightly with depth below the cloud tops, with a vertical shear that is less than was measured at 7°N at the southern rim of a 5-μm hotspot by the Galileo Probe Doppler Wind Experiment (DWE). This supports the idea that Jupiter's vertical shear may vary significantly with latitude. Our simulations suggest that the morphology of the mergers between vortices mainly depends on their maximum tangential velocities, the best results occurring when the tangential velocity is close to the velocity difference of the alternating jets constraining the zone in which the vortices are embedded. We use this correlation, together with the high-resolution data available for the White Ovals, to derive an empirical relationship between the maximum tangential velocity of a jovian vortex and its size, normalized by the strength and size of the encompassing shear zone. The Great Red Spot stands out as a significant anomaly to this relationship, but interestingly it is becoming less so with time. 相似文献
The utility of nonmetric, multidimensional-scaling techniques is demonstrated for the analysis and collection of environmental-cognition data. By comparing the multidimensional-scaling solutions of a real-setting map to scaling solutions for sketch maps and two psychophysical, distance-scaling procedures, we demonstrate that magnitude estimation of actual interpoint distances is comparable in accuracy to sketch maps when produced without constraints, or when subjects are given a specified list of landmarks to include on their maps. Triadic comparisons of actual interpoint distances were less accurate than the three other techniques. 相似文献
Recent wave reanalysis databases require the application of techniques capable of managing huge amounts of information. In this paper, several clustering and selection algorithms: K-Means (KMA), self-organizing maps (SOM) and Maximum Dissimilarity (MDA) have been applied to analyze trivariate hourly time series of met-ocean parameters (significant wave height, mean period, and mean wave direction). A methodology has been developed to apply the aforementioned techniques to wave climate analysis, which implies data pre-processing and slight modifications in the algorithms. Results show that: a) the SOM classifies the wave climate in the relevant “wave types” projected in a bidimensional lattice, providing an easy visualization and probabilistic multidimensional analysis; b) the KMA technique correctly represents the average wave climate and can be used in several coastal applications such as longshore drift or harbor agitation; c) the MDA algorithm allows selecting a representative subset of the wave climate diversity quite suitable to be implemented in a nearshore propagation methodology. 相似文献
We present an algorithm that allows fast and efficient detection of transits, including planetary transits, from light-curves. The method is based on building an ensemble of fiducial models and compressing the data using the moped compression algorithm. We describe the method and demonstrate its efficiency by finding planet-like transits in simulated Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) light-curves. We show that our method is independent of the size of the search space of transit parameters. In large sets of light-curves, we achieve speed-up factors of the order of 103 times over an optimized adaptive search in the χ2 space. We discuss how the algorithm can be used in forthcoming large surveys like Pan-STARRS and the Large Synoptic Survey Telescope (LSST), and how it may be optimized for future space missions like Kepler and COROT where most of the processing must be done on board. 相似文献
NGC 4649 (M60) is one of a handful of giant Virgo ellipticals. We have obtained Gemini/GMOS (Gemini North Multi-Object Spectrograph) spectra for 38 globular clusters (GCs) associated with this galaxy. Applying the multi-index χ2 minimization technique of Proctor and Sansom with the single stellar population models of Thomas, Maraston and Korn, we derive ages, metallicities and α-element abundance ratios. We find several young (2–3 Gyr old) supersolar metallicity GCs, while the majority are old (>10 Gyr), spanning a range of metallicities from solar to [Z/H]=−2 . At least two of these young GCs are at large projected radii of 17–20 kpc. The galaxy itself shows no obvious signs of a recent starburst, interaction or merger. A trend of decreasing α-element ratio with increasing metallicity is found. 相似文献