Frozen-anomaly transformation for the elliptic rendezvous problem     

Javier Roa  Jesús Peláez 《Celestial Mechanics and Dynamical Astronomy》2015,121(1):61-81

  相似文献   

Probabilistic estimates of future changes in California temperature and precipitation using statistical and dynamical downscaling   总被引：1，自引：0，他引：1  

David W. Pierce  Tapash Das  Daniel R. Cayan  Edwin P. Maurer  Norman L. Miller  Yan Bao  M. Kanamitsu  Kei Yoshimura  Mark A. Snyder  Lisa C. Sloan  Guido Franco  Mary Tyree 《Climate Dynamics》2013,40(3-4):839-856

Sixteen global general circulation models were used to develop probabilistic projections of temperature (T) and precipitation (P) changes over California by the 2060s. The global models were downscaled with two statistical techniques and three nested dynamical regional climate models, although not all global models were downscaled with all techniques. Both monthly and daily timescale changes in T and P are addressed, the latter being important for a range of applications in energy use, water management, and agriculture. The T changes tend to agree more across downscaling techniques than the P changes. Year-to-year natural internal climate variability is roughly of similar magnitude to the projected T changes. In the monthly average, July temperatures shift enough that that the hottest July found in any simulation over the historical period becomes a modestly cool July in the future period. Januarys as cold as any found in the historical period are still found in the 2060s, but the median and maximum monthly average temperatures increase notably. Annual and seasonal P changes are small compared to interannual or intermodel variability. However, the annual change is composed of seasonally varying changes that are themselves much larger, but tend to cancel in the annual mean. Winters show modestly wetter conditions in the North of the state, while spring and autumn show less precipitation. The dynamical downscaling techniques project increasing precipitation in the Southeastern part of the state, which is influenced by the North American monsoon, a feature that is not captured by the statistical downscaling.  相似文献   

The droughts of 1997 and 2005 in Amazonia: floodplain hydrology and its potential ecological and human impacts     

Javier Tomasella  Patrícia F. Pinho  Laura S. Borma  José A. Marengo  Carlos A. Nobre  Olga R. F. O. Bittencourt  Maria C. R. Prado  Daniel A. Rodriguez  Luz A. Cuartas 《Climatic change》2013,116(3-4):723-746

It is well known that most of the severe droughts in Amazonia, such as that of 1997, are El Niño-related. However, in 2005, the Amazon was affected by a severe drought that was not El Niño-related, as most of the rainfall anomalies that have happened in southwestern Amazonia are driven by sea surface temperature anomalies in the tropical North Atlantic. Earlier studies have analyzed both droughts in terms of their meteorological causes and impacts in terra firme (non-flooded) forests. This study compares the hydrological effects of both droughts on the Amazonian floodplain and discusses their potential ecological and human impacts based on an extensive literature review. The results revealed that the effects of the 2005 drought were exacerbated because rainfall was lower and evaporation rates were higher at the peak of the dry season compared to the 1997 drought. This induced a more acute depletion of water levels in floodplain lakes and was most likely associated with higher fish mortality rates. Based on the fact that the stem growth of many floodplain species is related to the length of the non-flooded period, it is hypothesized that the 1997 drought had more positive effects on floodplain forest growth than the 2005 drought. The fishing community of Silves in central Amazonia considered both droughts to have been equally severe. However, the 2005 drought was widely broadcasted by the press; therefore, the governmental mitigation efforts were more comprehensive. It is suggested that the availability of new communication technology and greater public awareness regarding environmental issues, combined with the new legal framework for assessing the severity of calamities in Brazil, are among the primary factors that explain the difference in societal response between the two droughts.  相似文献   

Climate change and infectious diseases: Can we meet the needs for better prediction?     

Xavier Rodó  Mercedes Pascual  Francisco J. Doblas-Reyes  Alexander Gershunov  Dáithí A. Stone  Filippo Giorgi  Peter J. Hudson  James Kinter  Miquel-Àngel Rodríguez-Arias  Nils Ch. Stenseth  David Alonso  Javier García-Serrano  Andrew P. Dobson 《Climatic change》2013,118(3-4):625-640

The next generation of climate-driven, disease prediction models will most likely require a mechanistically based, dynamical framework that parameterizes key processes at a variety of locations. Over the next two decades, consensus climate predictions make it possible to produce forecasts for a number of important infectious diseases that are largely independent of the uncertainty of longer-term emissions scenarios. In particular, the role of climate in the modulation of seasonal disease transmission needs to be unravelled from the complex dynamics resulting from the interaction of transmission with herd immunity and intervention measures that depend upon previous burdens of infection. Progress is also needed to solve the mismatch between climate projections and disease projections at the scale of public health interventions. In the time horizon of seasons to years, early warning systems should benefit from current developments on multi-model ensemble climate prediction systems, particularly in areas where high skill levels of climate models coincide with regions where large epidemics take place. A better understanding of the role of climate extremes on infectious diseases is urgently needed.  相似文献   

The NLTE Formation of Iron Lines Used in Solar Polarimetry     

Shchukina  Nataliya G.  Bueno  Javier Trujillo  Kostik  Roman I. 《Solar physics》1997,172(1-2):117-124

We study in some detail one-dimensional NLTE effects in solar Fei lines. The lines selected are frequently used in solar polarimetry, and also in studies of line asymmetries and for abundance determinations. Our model atom for Fei–Feii–Feiii is realistic: it takes account of multiplet structure and it includes over 200 bound–bound and bound–free transitions in detail. We use very efficient iterative methods for the self-consistent solution of the kinetic and radiative transfer equations (Auer, Fabiani Bendicho, and Trujillo Bueno, 1994). We have applied these fast methods of solution because they are suitable for the investigation of 2D and 3D NLTE transfer effects with multilevel atoms, which constitutes the next step of our ongoing research project on the iron line formation problem.  相似文献   

Onset of Convection,Heat Flow and Thickness of the Europa‘s ice Shell     

Ruiz  Javier 《Earth, Moon, and Planets》1997,77(2):99-104

The observational evidence given by Galileo spacecraft about Europa supports an icy rigid layer of several kilometers over another ductile layer of ice in convection, which floats over an internal ocean of liquid water. Before the onset of convection, heat is transmitted into the crust by conduction. The heat flow analysis in the potentially convective layer gives values higher than those obtained previously by tidal dissipation models, and suggests that the ice may be limited to a thin layer of ∼4 km total thickness. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Near Infrared Spectra of two Asteroids with low Tisserand Invariant     

Julie Ziffer  Humberto Campins  Javier Licandro  Noemi Pinilla-Alonso  Yanga Fernandez  Schelte J. Bus 《Earth, Moon, and Planets》2005,97(3-4):203-212

We present near infrared reflectance spectra from 0.8 to 2.5 μm of two asteroids with low Tisserand invariant, 1373 Cincinnati and 2906 Caltech. We compare our spectra with cometary nuclei and other asteroids in their class. Asteroids Cincinnati and Caltech have Tisserand invariant values of 2.72 and 2.97, respectively, values less than 3 are considered suggestive of cometary origin. The observed spectral slopes in the near-infrared are consistent with both the spectra of cometary nuclei and of primitive asteroids. However, both asteroids have features in the near-infrared that are not seen in cometary nuclei, but are present in other X-type asteroids. 1373 Cincinnati has a sharp slope change between 0.75 and 1.0 μm and 2906 Caltech has a broad and shallow absorption between 1.35 and 2.2 μm. Our attempts to model the visible and near-infrared spectrum of these two objects, with the components successfully used by Emery and Brown (2004, Icarus 164, 104–121) to fit Trojan asteroids, did not yield acceptable fits.Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract to the National Aeronautics and Space Administration.  相似文献   

Using SHRIMP zircon dating to unravel tectonothermal events in arc environments. The early Palaeozoic arc of NW Iberia revisited     

Jacobo Abati  Pedro Castieiras  Ricardo Arenas  Javier Fernndez‐Surez  Juan Gmez Barreiro  Joseph L. Wooden 《地学学报》2007,19(6):432-439

Abstract Dating of zircon cores and rims from granulites developed in a shear zone provides insights into the complex relationship between magmatism and metamorphism in the deep roots of arc environments. The granulites belong to the uppermost allochthonous terrane of the NW Iberian Massif, which forms part of a Cambro‐Ordovician magmatic arc developed in the peri‐Gondwanan realm. The obtained zircon ages confirm that voluminous calc‐alkaline magmatism peaked around 500 Ma and was shortly followed by granulite facies metamorphism accompanied by deformation at c. 480 Ma, giving a time framework for crustal heating, regional metamorphism, deformation and partial melting, the main processes that control the tectonothermal evolution of arc systems. Traces of this arc can be discontinuously followed in different massifs throughout the European Variscan Belt, and we propose that the uppermost allochthonous units of the NW Iberian Massif, together with the related terranes in Europe, constitute an independent and coherent terrane that drifted away from northern Gondwana prior to the Variscan collisional orogenesis.  相似文献   

On mean sea-level along the Brazilian coast     

A. R. de  Mesquita  A. S. Franco  J. Harari 《Geophysical Journal International》1986,87(1):67-77

Summary. (Part 1) Fourier analyses of mean monthly sea-level data from Belém, Fortaleza, Salvador and Imbituba, ports on the Brazilian coast, are made with simultaneous data of air temperature, sea surface atmospheric pressure, atmospheric precipitation and evaporation. Results show that the mean monthly sea-levels of ports below Recife's latitude show peaks in February-March and April-May which are apparently related to the seasonal temperature changes and the combined action of precipitation, winds and oceanographic large-scale changes. The port of Belém showed a stronger semi-annual seasonal component, which seems to be related to the alternate southern and northern hemispheres' influences of the atmospheric precipitation. (Part 2 of the paper presented at the Symposium concerned the longer term changes of sea-level, including an analysis of principal components. These subjects will be treated in a separate paper.)  相似文献   

On the expansion of supernova shells     

Carla Maceroni  Marco Salvati  Franco Pacini 《Astrophysics and Space Science》1974,28(1):205-212

We have investigated a simple model for the effects of a central pulsar on the expansion of supernova shells. Some numerical results relevant to the Crab Nebula are also reported.  相似文献