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Search Results: 1 - 10 of 219517 matches for " C. Bingen "
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Evidence of transport, sedimentation and coagulation mechanisms in the relaxation of post-volcanic stratospheric aerosols
D. Fussen,F. Vanhellemont,C. Bingen
Annales Geophysicae (ANGEO) , 2003,
Abstract: Spatio-temporal distributions of stratospheric aerosols, measured by the ORA instrument from August 1992 until May 1993, are presented in the latitude range (40° S–40° N). Particle total number density, mode radius and distribution width are derived and interpreted. The respective roles of advection, sedimentation and coagulation are discussed. We also identify clear transport/sedimentation patterns and we show the enhancement of coagulation in stagnation regions. Efficient transport of aerosol particles up to 50 km is suggested. Key words. Atmospheric composition and structure (aerosols and particles; middle atmosphere-composition and chemistry; volcanic effects)
A new regularized inversion method for the retrieval of stratospheric aerosol size distributions applied to 16 years of SAGE II data (1984–2000): method, results and validation
C. Bingen,F. Vanhellemont,D. Fussen
Annales Geophysicae (ANGEO) , 2003,
Abstract: We apply a regularization method for the optical inversion of SAGE II aerosol extinction profiles and derive the particle number density N, the mode radius r and width s of an effective lognormal aerosol size distribution. The constraint applied to the inversion scheme allows us to appreciably enhance the stability of the solution. Therefore, because of the disposal of a more stable inversion scheme and of the wide extend of SAGE II data in time and space, we were able to improve the estimation of the aerosol parameter profiles with respect to previous published retrievals and, hence, our knowledge of the aerosol distribution characteristics in space and time. After presenting the inversion method and retrieved profiles concerning the particle number density profile over the time period 1984–2000, we validate our results by means of data derived from both in situ and remote spectral measurements. We also discuss the limits of the comparison between the various types of measurements due to their respective particularities. The validation gives a satisfying agreement with other data sources for N and r as long as the mode radius is not too small compared to the shortest SAGE II wavelength, whereas s appears to be less easily retrieved with a good accuracy. Key words. Atmospheric composition and structure (aerosols and particles; middle atmosphere – composition and chemistry; volcanic effects)
A global climatology of stratospheric OClO derived from GOMOS measurement
C. Tétard,D. Fussen,F. Vanhellemont,C. Bingen
Atmospheric Measurement Techniques Discussions , 2013, DOI: 10.5194/amtd-6-3511-2013
Abstract: The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the European platform ENVISAT was dedicated to the study of the atmosphere of the Earth using the stellar occultation technique. The spectral range of the GOMOS spectrometer extends from the UV to the near infrared, allowing for the retrieval of species such as O3, NO2, NO3, H2O, O2, air density, aerosol extinction and OClO. Nevertheless, OClO can not be retrieved using a single GOMOS measurement because of the weak signal-to-noise ratio and the small optical thickness associated with this molecule. We present here the method used to detect this molecule by using several GOMOS measurements. It is based on a two-step approach. First, several co-located measurements are combined in a statistical way to build an averaged measurement with a higher signal-to-noise ratio. Then, a Differential Optical Absorption Spectroscopy (DOAS) method is applied to retrieve OClO slant column densities. The statistics of the sets of GOMOS measurements used to build the averaged measurement and the spectral window selection are analyzed. The obtained retrievals are compared to results from two balloon-borne instruments. It appears that the inter-comparisons of OClO are generally satisfying. Then, two nighttime climatologies of OClO slant column densities based on GOMOS averaged measurements are presented. The first depicts annual global pictures of OClO from 2003 to 2011. From this climatology, the presence of an OClO layer in the equatorial region at about 35 km is confirmed and strong concentrations of OClO in both polar regions are observed, a sign of chlorine activation. The second climatology is a monthly time series. It clearly shows the chlorine activation of the lower stratosphere during winter. Moreover the equatorial OClO layer is observed during all the years without any significant variations. Finally, the anti-correlation between OClO and NO2 is highlighted. This very promising method, applied on GOMOS measurements, allowed us to build the first nighttime climatology of OClO.
Simultaneous measurements of OClO, NO2 and O3 in the Arctic polar vortex by the GOMOS instrument
C. Tétard,D. Fussen,C. Bingen,N. Capouillez
Atmospheric Chemistry and Physics Discussions , 2009,
Abstract: We present the first nighttime measurements of OClO from a limb-viewing satellite instrument in the Arctic polar vortex. The relationship between OClO, NO2 and O3 slant column densities in the Arctic polar vortex are analyzed from the GOMOS measurements. The retrieval process is based on a differential optical absorption spectroscopy (DOAS) method applied on the weighted median GOMOS transmittances. A study about the longitudinal distributions of OClO, NO2 and O3 above 65° north in January 2008 is presented. It shows a strong halogen activation in the lower stratosphere and a strong denoxification in the entire stratosphere inside the Arctic polar vortex. Time series of temperatures and OClO, NO2 and O3 slant column densities for the winters 2002/2003 to 2007/2008 are also presented. They highlight the correlation between temperature, OClO and NO2. The GOMOS instrument appears to be a very suitable instrument for the monitoring of OClO, NO2 and O3 in the stratosphere during nighttime.
Simultaneous measurements of OClO, NO2 and O3 in the Arctic polar vortex by the GOMOS instrument
C. Tétard,D. Fussen,C. Bingen,N. Capouillez
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2009,
Abstract: We present the first nighttime measurements of OClO from a limb-viewing satellite instrument in the Arctic polar vortex. The relationship between OClO, NO2 and O3 slant column densities in the Arctic polar vortex are analyzed from the GOMOS measurements. The retrieval process is based on a differential optical absorption spectroscopy (DOAS) method applied on the weighted median GOMOS transmittances. A study of the longitudinal distributions of OClO, NO2 and O3 above 65° north in January 2008 is presented. It shows a strong halogen activation in the lower stratosphere and a strong denoxification in the entire stratosphere inside the Arctic polar vortex. Time series of temperatures and OClO, NO2 and O3 slant column densities for the winters 2002/2003 to 2007/2008 are also presented. They highlight the correlation between temperature, OClO and NO2. The GOMOS instrument appears to be a very suitable instrument for the monitoring of OClO, NO2 and O3 in the stratosphere during nighttime.
A 2003 stratospheric aerosol extinction and PSC climatology from GOMOS measurements on Envisat
F. Vanhellemont,D. Fussen,C. Bingen,E. Kyr?l?
Atmospheric Chemistry and Physics Discussions , 2005,
Abstract: Stratospheric aerosols play an important role in a number of atmospheric issues such as midlatitude ozone depletion, atmospheric dynamics and the Earth radiative budget. Polar stratospheric clouds on the other hand are a crucial factor in the yearly Arctic 5 and Antarctic ozone depletion. It is therefore important to quantify the stratospheric aerosol/PSC abundance. In orbit since March 2002, the GOMOS instrument onboard the European Envisat satellite has provided a vast aerosol extinction data set. In this paper we present an aerosol/PSC climatology that was constructed from this data set, together with a discussion of the results.
Zernike polynomials applied to apparent solar disk flattening for pressure profile retrievals
E. Dekemper, F. Vanhellemont, N. Mateshvili, G. Franssens, D. Pieroux, C. Bingen, C. Robert,D. Fussen
Atmospheric Measurement Techniques (AMT) & Discussions (AMTD) , 2013,
Abstract: We present a passive method for the retrieval of atmospheric pressure profiles based on the measurement of the apparent flattening of the solar disk as observed through the atmosphere by a spaceborne imager. This method was applied to simulated sunsets. It relies on accurate representation of the solar disk, including its limb darkening, and how its image is affected by atmospheric refraction. The Zernike polynomials are used to quantify the flattening in the Sun images. The inversion algorithm relies on a transfer matrix providing the link between the atmospheric pressure profile and a sequence of Zernike moments computed on the sunset frames. The transfer matrix is determined by a training dataset of pressure profiles generated from a standard climatology. The performance and limitations of the method are assessed by two test cases. Pressure profiles similar to the training dataset show that retrieval error can be up to 10 times smaller than the natural variability in the lower mesosphere, and up to 500 times smaller in the upper troposphere. Tests with other independent profiles emphasize the need for better representativeness of the training dataset.
Sin chivo expiatorio, no hay grupo: el caso de las administraciones públicas (No scapegoat, no group: the case of public administrations)
Josu Bingen Fernández Alcalde
OBETS : Revista de Ciencias Sociales , 2012,
Abstract: Con base en Girard, Bion, Tuckman, Morgan, Anzieu, o la Sociología Clínica se analiza la posición de “Chivo Expiatorio” como suceso universal en los procesos de desarrollo de grupos y equipos. Una etapa esperable y gestionable de su evolución; no un accidente a evitar ni un motivo para desmantelar los equipos laborales puestos en marcha. Sin chivo expiatorio no hay grupo, ni regeneración grupal. Toda grupalidad vive cíclicamente “el destronamiento” de una figura anterior de liderazgo con algún tipo de violencia sacrificial. Tal acontecimiento cierra una fase de conflicto importante e inaugura una renormalización grupal. Por ello, propone incluirla como fase propia en los modelos generales de desarrollo grupal.ABSTRACTBased on Girard, Bion, Tuckman, Morgan, Anzieu, or Clinical Sociology analyzes the position of "Scapegoat" as a universal event in the development processes of groups and work groups. An expected and manageable stage of its evolution, not an accident to avoid nor a reason for dismantling the set up work teams. No scapegoat no group, no regeneration group. All groups lives cyclically "the dethronement" of an earlier figure of leadership with some sort of sacrificial violence. This event closes a major conflict phase and inaugurates a renormalization group. It is therefore proposed to include itself as a phase in the generic models of group development.
Transcriptional analysis of the Escherichia coli ColV-Ia plasmid pS88 during growth in human serum and urine
Chloe Lemaitre, Philippe Bidet, Edouard Bingen, Stephane Bonacorsi
BMC Microbiology , 2012, DOI: 10.1186/1471-2180-12-115
Abstract: Quantification of plasmidic transcripts was obtained by quantitative real-time reverse transcription of extracted RNA, normalized on three housekeeping genes. The transcriptome of E. coli strain S88 grown in human serum and urine ex vivo were compared to that obtained during growth in Luria Bertani broth, with and without iron depletion. We also analyzed the transcriptome of a pS88-like plasmid recovered from a neonate with urinary tract infection. The transcriptome obtained after ex vivo growth in serum and urine was very similar to those obtained in iron-depleted LB broth. Genes encoding iron acquisition systems were strongly upregulated. ShiF and ORF 123, two ORFs encoding protein with hypothetical function and physically linked to aerobactin and salmochelin loci, respectively, were also highly expressed in iron-depleted conditions and may correspond to ancillary iron acquisition genes. Four ORFs were induced ex vivo, independently of the iron concentration. Other putative virulence genes such as iss, etsC, ompTp and hlyF were not upregulated in any of the conditions studied. Transcriptome analysis of the pS88-like plasmid recovered in vivo showed a similar pattern of induction but at much higher levels.We identify new pS88 genes potentially involved in the growth of E. coli meningitis strain S88 in human serum and urine.
A global climatology of the mesospheric sodium layer from GOMOS data during the 2002–2008 period
D. Fussen, F. Vanhellemont, C. Tétard, N. Mateshvili, E. Dekemper, N. Loodts, C. Bingen, E. Kyr l , J. Tamminen, V. Sofieva, A. Hauchecorne, F. Dalaudier, J.-L. Bertaux, G. Barrot, L. Blanot, O. Fanton d'Andon, T. Fehr, L. Saavedra, T. Yuan,C.-Y. She
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2010,
Abstract: This paper presents a climatology of the mesospheric sodium layer built from the processing of 7 years of GOMOS data. With respect to preliminary results already published for the year 2003, a more careful analysis was applied to the averaging of occultations inside the climatological bins (10° in latitude-1 month). Also, the slant path absorption lines of the Na doublet around 589 nm shows evidence of partial saturation that was responsible for an underestimation of the Na concentration in our previous results. The sodium climatology has been validated with respect to the Fort Collins lidar measurements and, to a lesser extent, to the OSIRIS 2003–2004 data. Despite the important natural sodium variability, we have shown that the Na vertical column has a marked semi-annual oscillation at low latitudes that merges into an annual oscillation in the polar regions,a spatial distribution pattern that was unreported so far. The sodium layer seems to be clearly influenced by the mesospheric global circulation and the altitude of the layer shows clear signs of subsidence during polar winter. The climatology has been parameterized by time-latitude robust fits to allow for easy use. Taking into account the non-linearity of the transmittance due to partial saturation, an experimental approach is proposed to derive mesospheric temperatures from limb remote sounding measurements.
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