Imaging of atmospheric gravity waves in the stratosphere and upper mesosphere using satellite and ground-based observations over Australia during the TWPICE campaign

Extent: 20p.During the Tropical Warm Pool International Cloud Experiment (TWPICE) an intense tropical low was situated between Darwin and Alice Springs, Australia. Observations made on 31 January 2006 by the Atmospheric Infrared Sounder instrument on the NASA Aqua satellite imaged the presence of atmospheric gravity waves (AGWs), at approximately 40 km altitude, with horizontal wavelengths between 200 and 400 km that were originating from the region of the storm. Airglow images obtained from Alice Springs (about 600 km from the center of the low) showed the presence of similar waves with observed periods of 1 to 2 h. The images also revealed the presence of 30- to 45-km-horizontal-wavelength AGWs with shorter observed periods of near 15 to 25 min. Ray tracing calculations show that (1) some of the long wavelength waves traveled on rays, without ducting, to the altitudes where the observations were obtained, and (2) shorter-period waves rapidly reached 85 km altitude at a horizontal distance close to the storm, thus occurring over Alice Springs only if they were trapped or ducted. The mesospheric inversion layer seen in the measured temperature data almost forms such a trapped region. The winds therefore critically control the formation of the trapped region. Wind profiles deduced from the available data show the plausibility for the formation of such a trapped region. Variations in the wind, however, would make ideal trapped region conditions short-lived, and this may account for the sporadic nature of the short-period wave observations.J. H. Hecht, M. J. Alexander, R. L. Walterscheid, L. J. Gelinas, R. A. Vincent, A. D. MacKinnon, J. M. Woithe, P. T. May, W. R. Skinner, M. G. Mlynczak, and J. M. Russell II

Observations of the phase-locked 2 day wave over the Australian sector using medium-frequency radar and airglow data

Extent: 22p.The quasi 2 day wave, with a nominal mean period just above 50 h, is a significant feature of the 80–100 km altitude region in both hemispheres. It becomes particularly prominent in the Southern Hemisphere summer at midlatitudes where, a short time after summer solstice, its amplitude rapidly increases and its mean period is found to be approximately 48 h, producing an oscillation phase locked in local time. This lasts for a few weeks. Presented here are observations of the meridional winds and airglow over two sites in Australia, for 4 years during the austral summers of 2003–2006. We show that during those times when the large-amplitude phase-locked 2 day wave (PL-TDW) is present the diurnal tide greatly decreases. This is consistent with the Walterscheid and Vincent (1996) model in which the PL-TDW derives its energy from a parametric excitation by the diurnal tide. These data also show that the diurnal tide is more suppressed and the PL-TDW amplitude is larger in odd-numbered years, suggesting a biannual effect. The airglow data indicated that, for the PL-TDW, the winds and temperature are nearly out of phase. When the PL-TDW is present airglow amplitudes can become quite large, a result dependent on the local time of the PL-TDW maximum. The airglow intensity response was, in general, much larger than what would be expected from the airglow temperature response, suggesting that the PL-TDW is causing a significant composition change possibly due to minor constituent transport.J. H. Hecht, R. L. Walterscheid, L. J. Gelinas, R. A. Vincent, I. M. Reid, and J. M. Woith

Einfluss des herbiziden Wirkstoffes Methabenzthiazuron auf die Feinstruktur des Photosyntheseapparates von Secale cereale L. (Winterroggen) unter Freilandbedingungen

SIGLETIB Hannover: DR 7561 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Seasonal variations of the nighttime O(1S) and OH (8-3) airglow intensity at Adelaide, Australia

Constituer une anthologie de la littérature belge d’expression française à l’usage des classes du secondaire est une entreprise courageuse, qui a connu déjà quelques précédents. On se souvient des versions belges du « Lagarde et Michard » (Bordas) et du « Chassang et Seninger » (Hachette) publiées respectivement par Robert Guiette aux alentours de 1960 et par Jacques De Caluwé en 1974, puis du volume de la non moins célèbre collection « Littérature et langage » des éditions Nathan publiée en ..

Analysis and interpretation of airglow and radar observations of quasi-monochromatic gravity waves in the upper mesosphere and lower thermosphere over Adelaide, Australia (35oS, 138oE)

Observations of wave-driven fluctuations in emissions from the OH Meinel (OHM) and O2 Atmospheric band were made with a narrow-band airglow imager located at Adelaide, Australia (35S, 138E) during the period April 1995 to January 1996. Simultaneous wind measurements in the 80-100 km region were made with a co-located MF radar. The directionality of quasi-monochromatic (QM) waves in the mesopause region is found to be highly anisotropic, especially during the solstices. During the summer, small-scale QM waves in the airglow are predominately poleward propagating, while during winter they are predominately equatorward. The directionality inferred from a Stokes analysis applied to the radar data also indicates a strong N-S anisotropy in summer and winter, but whether propagation is from the north or south cannot be determined from the analysis. The directionality of the total wave field (which contains incoherent as well as coherent features) derived from a spectral analysis of the images shows a strong E-W component, whereas, an E-W component is essentially absent for QM waves. The prevalence of QM waves is also strongly seasonally dependent. The prevalence is greatest in the summer and the least in winter and correlates with the height of the mesopause; whether it is above or below the airglow layers. The height of the mesopause is significant because for nominal thermal structures it is associated with a steep gradient in the Brunt-Väisälä frequency that causes the base of a lower thermospheric thermal duct to be located in the vicinity of the mesopause. We interpret the QM waves as waves trapped in the lower thermosphere thermal duct or between the ground and the layer of evanescence above the duct. Zonal winds can deplete the thermal duct by limiting access to the duct or by negating the thermal trapping. Radar measurements of the prevailing zonal wind are consistent with depletion of zonally propagating waves. During winter, meridional winds in the upper mesophere and lower thermosphere are weak and have no significant effect on meridionally propagating waves. However, during summer the winds in the duct region can significantly enhance ducting of southward propagating waves. The observed directionality of the waves can be explained in terms of the prevailing wind at mesopause altitudes and the seasonal variation of distant sources

Three-field photometer observations of short-period gravity wave intrinsic parameters in the 80 to 100 km height region

Copyright 2005 by the American Geophysical Union.A three-field photometer (3FP) for making observations of airglow in the Mesosphere Lower Thermosphere (MLT) region has been operated at the center of the large MF aerial array located near Adelaide (138°E, 35°S) since 1993. Observations of the 557.7 nm airglow intensity emitted by atomic oxygen (OI) at heights near 97 km and the 730.0 nm airglow intensity emitted by hydroxyl (OH) near 87 km have been made simultaneously with MF spaced antenna observations of wind velocities in the 80–100 km height region. The 3FP measures the intensity of the 557.7 nm airglow in three fields separated by about 13 km at heights near 97 km, and then the intensity of the 730 nm airglow in three fields separated by about 12 km at heights near 87 km, on a 60 s cycle. These data have been analyzed to yield gravity wave observed phase speeds and horizontal wavelengths. Simultaneous MF radar data have been analyzed to yield measurements of the neutral wind velocity in 2 km height steps in the 80–100 km height interval every 2 min, and these have been used together with the observed wave parameters to calculate intrinsic gravity wave parameters. This paper presents a very brief overview of the system, the motivation for the work, and preliminary analysis of the data from 1995 until 2000

Calidad y fiabilidad en la proyección de plantas industriales

El proyecto de una planta industrial y de sus instalaciones constituye una previsión de la producción que en éstas se llevará a cabo; es también un producto al que se asocian requisitos de calidad y fiabilidad al igual que a los productos finales que saldrán de sus instalaciones. Sin embargo, no siempre este enfoque se corresponde con el control de la calidad de los proyectos en las metodologías y regulaciones vigentes. El presente trabajo representa una contribución metodológica al aseguramiento de la calidad de este complejo producto que es una planta industrial, con un enfoque moderno para que sirva de base al perfeccionamiento de este complejo processo.<br>The following work is aimed lo describe a modern approach for quality assurance of industrial plants design by means of a methodological contribution that can be taken as a basis for design improvement. Key questions whose answers are the basis for a proper quality assurance approach oriented to this complex process are described. Main quality specifications are pointed out. finally, design process errors and their classified causes, quality improvement oriented countermeasures as well as reliability considerations and quality evaluation of design are also described