Search results for "Pau"
showing 10 items of 1636 documents
Quantitative View on the Processes Governing the Upscale Error Growth up to the Planetary Scale Using a Stochastic Convection Scheme
2019
Abstract Two diagnostics based on potential vorticity and the envelope of Rossby waves are used to investigate upscale error growth from a dynamical perspective. The diagnostics are applied to several cases of global, real-case ensemble simulations, in which the only difference between the ensemble members lies in the random seed of the stochastic convection scheme. Based on a tendency equation for the enstrophy error, the relative importance of individual processes to enstrophy-error growth near the tropopause is quantified. After the enstrophy error is saturated on the synoptic scale, the envelope diagnostic is used to investigate error growth up to the planetary scale. The diagnostics re…
Long-lived contrails and convective cirrus above the tropical tropopause
2017
Abstract. This study has two objectives: (1) it characterizes contrails at very low temperatures and (2) it discusses convective cirrus in which the contrails occurred. (1) Long-lived contrails and cirrus from overshooting convection are investigated above the tropical tropopause at low temperatures down to −88 °C from measurements with the Russian high-altitude research aircraft M-55 Geophysica, as well as related observations during the SCOUT-O3 field experiment near Darwin, Australia, in 2005. A contrail was observed to persist below ice saturation at low temperatures and low turbulence in the stratosphere for nearly 1 h. The contrail occurred downwind of the decaying convective system H…
Impact of Convectively Detrained Ice Crystals on the Humidity of the Tropical Tropopause Layer in Boreal Winter
2020
Deep convection detraining in the uppermost tropical troposphere is capable of transporting water vapor and ice into the tropical tropopause layer (TTL), but the impact of deep convection on the global and regional TTL water vapor budget remains uncertain. In particular, the role of convectively detrained ice crystals that remain suspended after active convection has subsided is not well understood. These ice crystals represent aging cirrus anvils detached from the convective core. We use a cloud microphysical model that tracks individual ice crystals throughout their lifetimes to quantify the impact of detrained ice on the humidity of the TTL during boreal winter. Convective influence of a…
The dynamics of tropospheric aerosols
1966
After a brief review of the present knowledge of the Stratospheric sulfate layer, several possible mechanisms of formation are discussed in detail. A direct transport of low tropospheric particles into the stratosphere by convective clouds penetrating the tropopause is not very likely because these penetrations are not high enough and because of the chemical composition of the stratospheric particles. DOI: 10.1111/j.2153-3490.1966.tb00286.x
The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)
2015
Abstract. In this study we examine the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in connection to a deep convective system. We use the Advanced Research Weather and Research Forecasting (WRF-ARW) model with a horizontal resolution of 333 m to examine this downward transport. The simulation reproduces the deep convective system, its timing and overshooting altitudes reasonably well compared to radar and aircraft observations. Passive tracers initialised at pre-storm times indicate the downward transport of air from the stratosphere to the upper troposphere as well as upward tr…
Modeling of biomass smoke injection into the lower stratosphere by a large forest fire (Part I): reference simulation
2006
Abstract. Wildland fires in boreal regions have the potential to initiate deep convection, so-called pyro-convection, due to their release of sensible heat. Under favorable atmospheric conditions, large fires can result in pyro-convection that transports the emissions into the upper troposphere and the lower stratosphere. Here, we present three-dimensional model simulations of the injection of fire emissions into the lower stratosphere by pyro-convection. These model simulations are constrained and evaluated with observations obtained from the Chisholm fire in Alberta, Canada, in 2001. The active tracer high resolution atmospheric model (ATHAM) is initialized with observations obtained by r…
Detection of reactive nitrogen containing particles in the tropopause region? Evidence for a tropical nitric acid trihydrage (NAT) belt
2008
The detection of nitric acid trihydrate (NAT, HNO<sub>3</sub>&times;3H<sub>2</sub>O) particles in the tropical transition layer (TTL) harmonizes our understanding of polar stratospheric cloud formation. Large reactive nitrogen (NO<sub>y</sub>) containing particles were observed on 8 August 2006 by instruments onboard the high altitude research aircraft M55-Geophysica near and below the tropical tropopause. The particles, most likely NAT, have diameters less than 6 &mu;m and concentrations below 10<sup>-4</sup> cm<sup>&minus;3</sup>. The NAT particle layer was repeatedly detected at altitudes between 15.1 and 17.5 km ove…
The influence of coping strategies and behavior on the physiological response to social stress in women: The role of age and menstrual cycle phase.
2016
There is information indicating that the variations induced by the menstrual cycle may influence the capacity of young women to respond to stress. The physiological response to stress changes across the stages of the lifespan; however, in spite of the great increase in life expectancy, the way women react after menopause, a period characterized by a dramatic decline in sex hormones, has not been sufficiently studied. The main objective of the study was to examine the capacity to respond to and recover from an acute social stressor in post-menopausal women compared to young women. The second objective was to investigate the consequences of behavior on the self-regulatory systems. We measured…
A social and environmental impact assessment of the Crucitas gold mining project in Costa Rica
2014
In 2008 Costa Rica was facing a critical time in its history. A five year mining moratorium had just ended and mining companies were interested in exploring untapped resources in the country. The country was facing important decisions with which development path to take. The Crucitas Mining Project (CMP) was an issue that the whole country had an opinion on; in fact the Constitutional Court of Costa Rica (SALA IV) was debating what to do with the CMP. The purpose of this study was to assist decision makers by providing a well-rounded assessment of the impacts the CMP would have. The goal of this study was to evaluate whether it would be better for Costa Rica to let the mining operation cont…
Paulo Emílio Sales Gomes ou la critique à contre-courant
2016
International audience; Paulo Emilio Sales Gomes, intellectuel, homme de lettres et fondateur de la Cinemateca Brasileira, fait partie des personnalités essentielles de la critique de cinéma internationale. Grand défenseur du cinéma brésilien qu'il contribue à révéler (Cinema Novo), Sales Gomes est un personnage à multiples facettes : militant politique, critique, essayiste, historien et conservateur de la première cinémathèque du Brésil. Auteur de Panorama du cinéma brésilien : 1896/1966 (1970), Humberto Mauro, Cataguases, Cinearte (1974), ainsi que des nouvelles littéraires Três mulheres de 3 pppês (1977), (traduit en français P... comme Polydore ― 1986), il reste essentiellement connu en…