Characteristics and organization of precipitating features during NAME 2004 and their relationship to environmental conditions

2008 Fall.The focus of this study is to examine the characteristics of convective precipitating features (PFs) during the 2004 North American Monsoon Experiment (NAME) and their precursor environmental conditions. The goal is to gain a better insight into the predictability and variability of warm season convective processes in the southern portion of the North American Monsoon core region. The organization and characteristics of PFs are evaluated using composite radar reflectivity images over the southern portion of the Gulf of California. The environmental conditions are assessed using satellite images and a plethora of atmospheric observational analysis maps, such as winds at multiple levels, upper-level divergence, vorticity, vertical air motion, moisture and vertical cross-sections. Our study reveals that most PFs occurred during the afternoon and evening over land, especially near the foothills of the Sierra Madre Occidental. The vast majority of the precipitating features (~95%) were small, isolated, unorganized, short-lived convective cells. Mesoscale convective systems (MCSs) made up only 5% of the PF population. Nonetheless, these large, long-lived, precipitating features were responsible for 72% of the total precipitation within the radar composite region. An analysis of the number and rainfall produced by these MCSs revealed that they were not constant from day to day, but rather, varied significantly throughout NAME. We found that MCSs were more frequent when the atmosphere is thermodynamically unstable and the wind shear or large-scale dynamics favors the development of organized convection. Lastly, we examined the synoptic conditions associated with episodes of above average MCS rainfall in the southern portion of the NAME core region. Tropical waves were found to be an essential source of moisture and instability in the region. We also found that transient upper-level inverted troughs interact with the upper-level anticyclone to produce a "North American Monsoon Jet Streak" that created favorable dynamical uplift and wind shear conditions for MCS development

A BI-LEVEL SCHEME FOR ASSESSING THE IMPACT OF AIR TRANSPORTATION ON LOCAL DEVELOPMENT

An approach to assess the impact of the creation or expansion of an air transport infrastructure over regional development is proposed in this paper. Effective long term planning of this costly investment requires performing an overall analysis of socio-economic consequences through long term forecasting, scenario generation and risk analysis. One of main aspects of this task is related with the estimation of future demand over the modified transportation network which attends the considered region. The proposed approach makes use of two complementary models: One model is devoted to demand forecasting taking into account the modified accessibility of the multimodal transportation network, the other one defines the global transport supply according to a profit maximization behavior for the involved transport system. The demand forecasting process is based on an entropy maximization approach with flexible origin-destination levels to determine the intensity and the distribution of new origin-destination vectors. A two level solution technique considering vehicle flows at the first level and the payload/passengers flows at the second level is introduced. The proposed solution scheme is composed of an iterative process between the current solution for demand forecasting and the supply optimization problem: the entropy maximizing distribution problem provides the origin-destination matrix given a cost/capacity structure, while the supply optimization problem provides this cost/capacity structure resulting from the accessibility level, given the updated origin-destination vectors. The proposed approach is illustrated in the case of a fast developing rural agro-industrial area in central Brazil, where the consequences of the installation of a medium size airport are assessed.

Radar perspective on the variability of tropical convection characteristics over the southwestern Amazon and eastern Pacific regions

Spring 2003.Includes bibliographical references.The focus of this study is to evaluate the intra-regional and inter-regional variability of tropical convection characteristics in the southwestern Amazon and eastern Pacific warm-pool regions. Convection is examined using radar data collected during two tropical field experiments: TRMM-LBA (Tropical Rainfall Measuring Mission - Large Scale Biosphere-Atmosphere in Amazonia) and EPIC (Eastern Pacific Investigation of Climate Processes in the Coupled Ocean-Atmosphere System). In each of the two tropical regions studied, two distinct wind regimes have been observed to occur. In the southwest Amazon, one wind regime was called easterly regime and the other westerly regime. These changes in wind regime have been previously shown to be associated with the passage of baroclinic waves in the subtropical parts of Brazil and the formation of a synoptic-scale feature known as the South Atlantic Convergence Zone. In the east Pacific, one wind regime was called the northerly regime and the other southerly regime. The changes in wind regime over the east Pacific have been observed to be associated with the passage of easterly waves. The variability of the convective characteristics is evaluated in each region as a function of time of day and wind circulation. Some of the features used to evaluate the characteristics of convection include convective area, convective fraction, reflectivity profiles, rain rates, warm rain statistics and ice fraction. The results presented in this thesis showed that the easterly and northerly wind regimes more frequently featured characteristics of stronger convection: greater rain rates, greater reflectivities and convective fractions, deeper convective cores and smaller fractions of warm-rain-producing areas. The results also showed that the easterly regime was associated with higher ice fractions. The diurnal cycle results indicated that convection initiates in the morning and peaks in the afternoon over the southwest portion of the Amazon, whereas in the east Pacific the convection initiates after sunset and peaks just before sunrise. Variations associated with wind regime were shown to be more intense in the southwest Amazon. It was also found that the east Pacific region presented larger convective areas and convective fractions than the southwest portion of the Amazon. The eastern Pacific region was also associated with larger fractions of warm rain areas, but overall the fraction of rainfall owed to warm processes was very small and approximately the same in both regions.Sponsored by the National Science Foundation ATM-0002256

Preservando a Pauliceia: DPH, CONPRESP e o património paulistano: Preserving the Pauliceia: DPH, CONPRESP and the paulistan heritage

Este artigo apresenta os processos de criação dos dois órgãos de preservação do património da cidade de São Paulo, o DPH e o CONPRESP, criados em 1975 e 1985, respetivamente. Pensando o patrimônio paulistano como “herdeiro” do Departamento de Cultura, surgido na década de 1930 e partindo dos documentos legais que balizaram a criação destes dois órgãos, mas não nos limitando a eles, refizemos o percurso do processo de elaboração e circulação dos projetos de criação dos órgãos, os sujeitos envolvidos neste processo, as instituições que foram seu palco e os objetivos e conceções de patrimônio que os nortearam. Por fim, pensamos os desafios a que estão submetidos atualmente, suas dificuldades e avanços e as perspetivas de atuação no próximo período

Measurement of ψ(2S) production as a function of charged-particle pseudorapidity density in pp collisions at √s = 13 TeV and p–Pb collisions at √sNN = 8.16 TeV with ALICE at the LHC

Production of inclusive charmonia in pp collisions at center-of-mass energy of √ s = 13 TeV and p–Pb collisions at center-of-mass energy per nucleon pair of √ sNN = 8.16 TeV is studied as a function of charged-particle pseudorapidity density with ALICE. Ground and excited charmonium states (J/ψ, ψ(2S)) are measured from their dimuon decays in the interval of rapidity in the center-of-mass frame 2.5 < ycms < 4.0 for pp collisions, and 2.03 < ycms < 3.53 and −4.46 < ycms < −2.96 for p–Pb collisions. The charged-particle pseudorapidity density is measured around midrapidity (|η| < 1.0). In pp collisions, the measured charged-particle multiplicity extends to about six times the average value, while in p-Pb collisions at forward (backward) rapidity a multiplicity corresponding to about three (four) times the average is reached. The ψ(2S) yield increases with the charged-particle pseudorapidity density. The ratio of ψ(2S) over J/ψ yield does not show a significant multiplicity dependence in either colliding system, suggesting a similar behavior of J/ψ and ψ(2S) yields with respect to charged-particle pseudorapidity density. Results for the ψ(2S) yield and its ratio with respect to J/ψ agree with available model calculations

Measurement of inclusive and leading subjet fragmentation in pp and Pb–Pb collisions at √sNN = 5.02 TeV

This article presents new measurements of the fragmentation properties of jets in both proton–proton (pp) and heavy-ion collisions with the ALICE experiment at the Large Hadron Collider (LHC). We report distributions of the fraction zr of transverse momentum carried by subjets of radius r within jets of radius R. Charged-particle jets are reconstructed at midrapidity using the anti-kT algorithm with jet radius R = 0.4, and subjets are reconstructed by reclustering the jet constituents using the anti-kT algorithm with radii r = 0.1 and r = 0.2. In proton–proton collisions, we measure both the inclusive and leading subjet distributions. We compare these measurements to perturbative calculations at next-to-leading logarithmic accuracy, which suggest a large impact of threshold resummation and hadronization effects on the zr distribution. In heavy-ion collisions, we measure the leading subjet distributions, which allow access to a region of harder jet fragmentation than has been probed by previous measurements of jet quenching via hadron fragmentation distributions. The zr distributions enable extraction of the parton-to-subjet fragmentation function and allow for tests of the universality of jet fragmentation functions in the quark–gluon plasma (QGP). We find no significant modification of zr distributions in Pb–Pb compared to pp collisions. However, the distributions are also consistent with a hardening trend for zr < 0.95, as predicted by several jet quenching models. As zr → 1 our results indicate that any such hardening effects cease, exposing qualitatively new possibilities to disentangle competing jet quenching mechanisms. By comparing our results to theoretical calculations based on an independent extraction of the parton-to-jet fragmentation function, we find consistency with the universality of jet fragmentation and no indication of factorization breaking in the QGP

Two-particle transverse momentum correlations in pp and p-Pb collisions at energies available at the CERN Large Hadron Collider

Two-particle transverse momentum differential correlators, recently measured in Pb-Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms and infer transport properties, such as the ratio of shear viscosity to entropy density, of the medium created in Pb-Pb collisions. The longitudinal long-range correlations and the large azimuthal anisotropy measured at low transverse momenta in small collision systems, namely pp and p-Pb, at LHC energies resemble manifestations of collective behavior. This suggests that locally equilibrated matter may be produced in these small collision systems, similar to what is observed in Pb-Pb collisions. In this work, the same twoparticle transverse momentum differential correlators are exploited in pp and p-Pb collisions at √s = 7 TeV and √sNN = 5.02 TeV, respectively, to seek evidence for viscous effects. Specifically, the strength and shape of the correlators are studied as a function of the produced particle multiplicity to identify evidence for longitudinal broadening that might reveal the presence of viscous effects in these smaller systems. The measured correlators and their evolution from pp and p-Pb to Pb-Pb collisions are additionally compared to predictions from Monte Carlo event generators, and the potential presence of viscous effects is discussed

Dielectron production at midrapidity at low transverse momentum in peripheral and semi-peripheral Pb–Pb collisions at √sNN = 5.02 TeV

The first measurement of the e+e − pair production at low lepton pair transverse momentum (pT,ee) and low invariant mass (mee) in non-central Pb–Pb collisions at √ sNN = 5.02 TeV at the LHC is presented. The dielectron production is studied with the ALICE detector at midrapidity (|ηe| < 0.8) as a function of invariant mass (0.4 ≤ mee < 2.7 GeV/c 2 ) in the 50–70% and 70–90% centrality classes for pT,ee < 0.1 GeV/c, and as a function of pT,ee in three mee intervals in the most peripheral Pb–Pb collisions. Below a pT,ee of 0.1 GeV/c, a clear excess of e+e − pairs is found compared to the expectations from known hadronic sources and predictions of thermal radiation from the medium. The mee excess spectra are reproduced, within uncertainties, by different predictions of the photon–photon production of dielectrons, where the photons originate from the extremely strong electromagnetic fields generated by the highly Lorentz-contracted Pb nuclei. Lowest-order quantum electrodynamic (QED) calculations, as well as a model that takes into account the impact-parameter dependence of the average transverse momentum of the photons, also provide a good description of the pT,ee spectra. The measured q hp 2 T,eei of the excess pT,ee spectrum in peripheral Pb–Pb collisions is found to be comparable to the values observed previously at RHIC in a similar phase-space region

J/ψ production at midrapidity in p-Pb collisions at √sNN = 8.16 TeV

The production of inclusive, prompt and non-prompt J/ψ was studied for the first time at midrapidity (−1.37 2 GeV/c. The study of the J/ψ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13 µb −1 . The proton-proton reference cross section for inclusive J/ψ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the pT-differential J/ψ production cross sections. The pT-differential nuclear modification factors RpPb of inclusive, prompt, and non-prompt J/ψ are consistent with unity and described by theoretical models implementing only nuclear shadowing

Production of pions, kaons, and protons as a function of the relative transverse activity classifier in pp collisions at √s = 13 TeV

Abstract: The production of π ±, K±, and (p)p is measured in pp collisions at √ s = 13 TeV in different topological regions of the events. Particle transverse momentum (pT) spectra are measured in the “toward”, “transverse”, and “away” angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, RT = NT/hNTi, is used to group events according to their UE activity, where NT is the measured charged-particle multiplicity per event in the transverse region and hNTi is the mean value over all the analysed events. The first measurements of identified particle pT spectra as a function of RT in the three topological regions are reported. It is found that the yield of high transverse momentum particles relative to the RT-integrated measurement decreases with increasing RT in both the toward and the away regions, indicating that the softer UE dominates particle production as RT increases and validating that RT can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing RT. This hardening follows a mass ordering, being more significant for heavier particles. Finally, it is observed that the pT-differential particle ratios (p + p)/(π + + π −) and (K+ + K−)/(π + + π −) in the low UE limit (RT → 0) approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce e +e − results