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Luigi R. Bedin † Santi Cassisi Fiorella Castelli Giampaolo Piotto Jay Anderson Maurizio Salaris Yazan Momany Adriano Pietrinferni 《Monthly notices of the Royal Astronomical Society》2005,357(3):1038-1048
We propose a zero-point photometric calibration of the data from the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) on board the Hubble Space Telescope , based on a spectrum of Vega and the most up-to-date in-flight transmission curves of the camera. This calibration is accurate at the level of a few hundredths of a magnitude. The main purpose of this effort is to transform the entire set of evolutionary models into a simple observational photometric system for ACS/WFC data, and to make them available to the astronomical community. We provide the zero-points for the most used ACS/WFC bands, and give basic recipes for calibrating both the observed data and the models. We also present the colour–magnitude diagram from ACS data of five Galactic globular clusters, spanning the metallicity range −2.2 <[Fe/H] < −0.04 , and we provide fiducial points representing their sequences from several magnitudes below the turn-off to the red giant branch tip. The observed sequences are compared with the models in the newly defined photometric system. 相似文献
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Mauro Giudici Stefano Margiotta Fiorella Mazzone Sergio Negri Chiara Vassena 《Environmental Earth Sciences》2012,67(7):1891-1907
The control exerted by the hydrostratigraphic structure on aquifer recharge, groundwater flow and discharge along the coastal areas of a Mediterranean basin (Salento peninsula, about 5,000?km2 wide, southern Italy) is assessed through the development and application of a groundwater flow model based on the reconstruction of the hydrostratigraphic architecture at the regional scale. The hydrostratigraphic model, obtained by processing surface and subsurface data, is applied to map the top of the main aquifer, which is hosted in the deep hydrostratigraphic unit corresponding to Cretaceous and Oligocene limestones with complex geometrical relationships with the sea. It is also used to estimate the aquifer recharge, which occurs by percolation through overlying younger sediments with low permeability. These data are completed with information about the soil use to estimate water abstraction for irrigation and with literature data to estimate the water abstraction for drinking and industrial purposes. The above-sketched conceptual model is the basis for a finite difference groundwater 2D pseudo-stationary flow model, which assumes the following fundamental approximations: the fractured and karst limestone hydrostratigraphic unit can be approximated, at the model scale, as a continuous medium for which the discrete Darcy??s law is valid; the transition zone between salt and fresh water is so small with respect to the grid spacing that the Ghyben?CHerzberg??s approximation for a sharp interface can be applied. Along the coastline different boundary conditions are assigned if the top of the limestone hydrostratigraphic unit lies either above the sea level (the aquifer has a free surface and fresh water is drained), or below the sea level (the aquifer is under pressure and the contact with sea occurs off-shore). The groundwater flow model correctly predicts the areas where the aquifer is fully saturated with salt water. 相似文献
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Young, rapidly rotating neutron stars could accelerate ions from their surfaces to energies of ∼1 PeV. If protons reach such energies, they will produce pions (with low probability) through resonant scattering with X-rays from the stellar surface. The pions subsequently decay to produce muon neutrinos. Here, we calculate the energy spectrum of muon neutrinos, and estimate the event rates at Earth. The spectrum consists of a sharp rise at ∼50 TeV, corresponding to the onset of the resonance, above which the flux drops with neutrino energy as ε−2 ν up to an upper energy cut-off that is determined by either kinematics or the maximum energy to which protons are accelerated. We estimate event rates as high as 10–100 km−2 yr−1 from some candidates, a flux that would be easily detected by IceCube. Lack of detection would allow constraints on the energetics of the poorly understood pulsar magnetosphere. 相似文献
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Fiorella Castelli 《Astrophysics and Space Science》1977,49(1):179-197
The identification, the equivalent widths, the profiles and the radial velocities as deduced from 18 spectra of Aurigae are presented and discussed.The observations have been made at the Astronomical Observatory of Haute Provence (CNRS). This work has been partially supported by a contract of Consiglio Nazionale delle Ricerche (CNR). 相似文献
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Stable water isotope ratios are measured as a tracer of environmental processes in materials such as leaves, soils, and lakes. Water in these archives may experience evaporation, which increases the abundance of heavy isotopologues proportionally to the gradients in humidity and isotope ratio between the evaporating water and the surrounding atmosphere. The isotope ratio of the atmosphere has been difficult to measure until recently, and measurements remain scarce. As a result, several assumptions have been adopted to estimate isotope ratios of atmospheric water vapour. Perhaps the most commonly employed assumption in terrestrial environments is that water vapour is in isotopic equilibrium with precipitation. We evaluate this assumption using an eight‐member ensemble of general circulation model (GCM) simulations that include explicit calculation of isotope ratios in precipitation and vapour. We find that across the model ensemble, water vapour is typically less depleted in heavy isotopologues than expected if it were in equilibrium with annual precipitation. Atmospheric vapour likely possesses higher‐than‐expected isotope ratios because precipitation isotope ratios are determined by atmospheric conditions that favour condensation, which do not reflect atmospheric mixing and advection processes outside of precipitation events. The effect of this deviation on theoretical estimates of isotope ratios of evaporating waters scales with relative humidity. As a result, the equilibrium assumption gives relatively accurate estimates of the isotope ratios of evaporating waters in low latitudes but performs increasingly poorly at increasing latitudes. Future studies of evaporative water pools should include measurements of atmospheric isotope ratios or constrain potential bias with isotope‐enabled GCM simulations. 相似文献
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Guillaume?FortinEmail authorView author&#;s OrcID profile Fiorella?Acquaotta Simona?Fratianni 《Theoretical and Applied Climatology》2017,130(1-2):163-172
The majority of natural hazards that affect Canadian territory are the result of extreme climate and weather conditions. Among these weather hazards, some can be calculated from the application of thresholds for minimum and maximum temperatures at a daily or monthly timescale. These thermal indices allowed the prediction of extreme conditions that may have an impact on the human population by affecting, for example, health, agriculture, and water resources. In this article, we discuss the methods used (RHtestsV4, SPLIDHOM, ClimPACT) then describe the steps followed to calculate the indices, including how we dealt with the problem of missing data and the necessity to identify a common methodology to analyze the time series. We also present possible solutions for ensuring the quality of meteorological data. We then present an overview of the results, namely the main trends and variability of extreme temperature for seven stations located in the Gaspé Peninsula from 1974 to 2013. Our results indicate some break points in time series and positive trends for most indices related to the rise of the temperatures but indicate a negative trend for the indices related to low temperatures for most stations during the study period. 相似文献
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Cesar Aybar Carlos Fernández Adrian Huerta Waldo Lavado Fiorella Vega Oscar Felipe-Obando 《水文科学杂志》2020,65(5):770-785
ABSTRACTA new gridded rainfall dataset available for Peru is introduced, called PISCOp V2.1 (Peruvian Interpolated data of SENAMHI’s Climatological and Hydrological Observations). PISCOp has been developed for the period 1981 to the present, with an average latency of eight weeks at 0.1° spatial resolution. The merging algorithm is based on geostatistical and deterministic interpolation methods including three different rainfall sources: (i) the national quality-controlled and infilled raingauge dataset, (ii) radar-gauge merged precipitation climatologies and (iii) the Climate Hazards Group Infrared Precipitation (CHIRP) estimates. The validation results suggest that precipitation estimates are acceptable showing the highest performance for the Pacific coast and the western flank of the Andes. Furthermore, a meticulous quality-control and gap-infilling procedure allowed us to reduce the formation of inhomogeneities (non-climatic breaks). The dataset is publicly available at https://piscoprec.github.io/ and is intended to support hydrological studies and water management practices. 相似文献
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Jennifer J. Follstad Shah Ryan Bares Brenda B. Bowen Gabriel J. Bowen David R. Bowling David P. Eiriksson Benjamin Fasoli Richard P. Fiorella Anna Gannet Hallar Sarah J. Hinners John D. Horel Alexander A. Jacques Logan R. Jamison John C. Lin Daniel L. Mendoza Logan E. Mitchell Diane E. Pataki Sarah McKenzie Skiles Rose M. Smith Margaret A. Wolf Paul D. Brooks 《水文研究》2021,35(9):e14352
The 2085 km2 Jordan River Basin, and its seven sub-catchments draining the Central Wasatch Range immediately east of Salt Lake City, UT, are home to an array of hydrologic, atmospheric, climatic and chemical research infrastructure that collectively forms the Wasatch Environmental Observatory (WEO). WEO is geographically nested within a wildland to urban land-use gradient and built upon a strong foundation of over a century of discharge and climate records. A 2200 m gradient in elevation results in variable precipitation, temperature and vegetation patterns. Soil and subsurface structure reflect systematic variation in geology from granitic, intrusive to mixed sedimentary clastic across headwater catchments, all draining to the alluvial or colluvial sediments of the former Lake Bonneville. Winter snowfall and spring snowmelt control annual hydroclimate, rapid population growth dominates geographic change in lower elevations and urban gas and particle emissions contribute to episodes of severe air pollution in this closed-basin. Long-term hydroclimate observations across this diverse landscape provide the foundation for an expanding network of infrastructure in both montane and urban landscapes. Current infrastructure supports both basic and applied research in atmospheric chemistry, biogeochemistry, climate, ecology, hydrology, meteorology, resource management and urban redesign that is augmented through strong partnerships with cooperating agencies. These features allow WEO to serve as a unique natural laboratory for addressing research questions facing seasonally snow-covered, semi-arid regions in a rapidly changing world and an excellent facility for providing student education and research training. 相似文献
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