278,703 research outputs found
DroughtScape- Summer 2010
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International Work- Murcia, Spain, Jun
The Ricci flow on a cylinder
In this paper we study the Ricci flow on surfaces homeomorphic to a cylinder
(that is, a product of the circle with a compact interval). We prove longtime
existence results, results on the asymptotic behavior of the flow, and we
report on an interesting phenomenon: convergence to constant curvature in the
normalised flow,under certain assumptions on the initial data, cannot be
exponential.Comment: Comments and criticism more than welcom
Phase diagram of orbital-selective Mott transitions at finite temperatures
Mott transitions in the two-orbital Hubbard model with different bandwidths
are investigated at finite temperatures. By means of the self-energy functional
approach, we discuss the stability of the intermediate phase with one orbital
localized and the other itinerant, which is caused by the orbital-selective
Mott transition (OSMT). It is shown that the OSMT realizes two different
coexistence regions at finite temperatures in accordance with the recent
results of Liebsch. We further find that the particularly interesting behavior
emerges around the special condition and J=0, which includes a new type
of the coexistence region with three distinct states. By systematically
changing the Hund coupling, we establish the global phase diagram to elucidate
the key role played by the Hund coupling on the Mott transitions.Comment: 4 pages, 6 figure
Validation of a global satellite rainfall product for real time monitoring of meteorological extremes
The real time monitoring of storms is important for the management and prevention of flood risks. However, in the southeast of Spain, it seems that the density of the rain gauge network may not be sufficient to adequately characterize the rainfall spatial distribution or the high rainfall intensities that are reached during storms. Satellite precipitation products such as PERSIANN-CCS (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks - Cloud Classification System) could be used to complement the automatic rain gauge networks and so help solve this problem. However, the PERSIANN-CCS product has only recently become available, so its operational validity for areas such as south-eastern Spain is not yet known. In this work, a methodology for the hourly validation of PERSIANN-CCS is presented. We used the rain gauge stations of the SIAM (Sistema de Información Agraria de Murcia) network to study three storms with a very high return period. These storms hit the east and southeast of the Iberian Peninsula and resulted in the loss of human life, major damage to agricultural crops and a strong impact on many different types of infrastructure. The study area is the province of Murcia (Region of Murcia), located in the southeast of the Iberian Peninsula, covering an area of more than 11,000 km2 and with a population of almost 1.5 million. In order to validate the PERSIANN-CCS product for these three storms, contrasts were made with the hyetographs registered by the automatic rain gauges, analyzing statistics such as bias, mean square difference and Pearson’s correlation coefficient. Although in some cases the temporal distribution of rainfall was well captured by PERSIANN-CCS, in several rain gauges high intensities were not properly represented. The differences were strongly correlated with the rain gauge precipitation, but not with satellite-obtained rainfall. The main conclusion concerns the need for specific local calibration for the study area if PERSIANN-CCS is to be used as an operational tool for the monitoring of extreme meteorological phenomena.This work is the result of a postdoctoral contract funded by Saavedra Fajardo programme (Ref. 20023/SF/16) of the Consejería de Educación y Universidades of CARM (Autonomous Community of Murcia Region), by the Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia. The support and availability of information from the Center for Hydrometeorology and Remote Sensing of University of California-Irvine (USA), and from Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA) of CARM are also acknowledged
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