Vignette d'image

Matthey-De-L'Endroit, Renaud

Nom
Matthey-De-L'Endroit, Renaud
Affiliation principale
Fonction
Ancien.ne collaborateur.trice
Identifiants
https://libra.unine.ch/handle/123456789/491

Résultat de la recherche

Filtres

4
4
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 4 sur 4
  • Publication
    Accès libre
    Frequency of Boundary-Layer-Top Fluctuations in Convective and Stable Conditions Using Laser Remote Sensing
    (2010)
    Martucci, Giovanni
    ;
    Matthey-De-L'Endroit, Renaud 
    ;
    Mitev, Valentin
    ;
    Richner, Hans
    The planetary boundary-layer (PBL) height is determined with high temporal and altitude resolution from lidar backscatter profiles. Then, the frequencies of daytime thermal updrafts and downdrafts and of nighttime gravity waves are obtained applying a fast Fourier transform on the temporal fluctuation of the PBL height. The principal frequency components of each spectrum are related to the dominant processes occurring at the daytime and nighttime PBL top. Two groups of cases are selected for the study: one group combines daytime cases, measured in weak horizontal wind conditions and dominated by convection. The cases show higher updraft and downdraft frequencies for the shallow, convective boundary layer and lower frequencies for a deep PBL. For cases characterized by strong horizontal winds, the frequencies directly depend on the wind speed. The temporal variation of the PBL height is determined also in the likely presence of lee waves. For nighttime cases, the main frequency components in the spectra do not show a real correlation with the nocturnal PBL height. Altitude fluctuations of the top of the nocturnal boundary layer are observed even though the boundary layer is statically stable. These oscillations are associated with the wind shear effect and with buoyancy waves at the PBL top.
  • Publication
    Accès libre
    Unprecedented evidence for deep convection hydrating the tropical stratosphere
    (2008)
    Corti, T.
    ;
    Luo, B. P.
    ;
    de Reus, M.
    ;
    Brunner, D.
    ;
    Cairo, F.
    ;
    Mahoney, M. J.
    ;
    Martucci, G.
    ;
    Matthey-De-L'Endroit, Renaud 
    ;
    Mitev, Valentin
    ;
    dos Santos, F. H.
    ;
    Schiller, C.
    ;
    Shur, G.
    ;
    Sitnikov, N. M.
    ;
    Spelten, N.
    ;
    Vössing, H. J.
    ;
    Borrmann, S.
    ;
    Peter, T.
    We report on in situ and remote sensing measurements of ice particles in the tropical stratosphere found during the Geophysica campaigns TROCCINOX and SCOUT-O3. We show that the deep convective systems penetrated the stratosphere and deposited ice particles at altitudes reaching 420 K potential temperature. These convective events had a hydrating effect on the lower tropical stratosphere due to evaporation of the ice particles. In contrast, there were no signs of convectively induced dehydration in the stratosphere.
  • Publication
    Accès libre
    Morphology of the tropopause layer and lower stratosphere above a tropical cyclone: a case study on cyclone Davina (1999)
    (2008)
    Cairo, F.
    ;
    Buontempo, C.
    ;
    MacKenzie, A. R.
    ;
    Schiller, C.
    ;
    Volk, C. M.
    ;
    Adriani, A.
    ;
    Mitev, Valentin
    ;
    Matthey-De-L'Endroit, Renaud 
    ;
    Di Donfrancesco, G.
    ;
    Oulanovsky, A.
    ;
    Ravegnani, F.
    ;
    Yushkov, V.
    ;
    Snels, M.
    ;
    Cagnazzo, C.
    ;
    Stefanutti, L.
    During the APE-THESEO mission in the Indian Ocean the Myasishchev Design Bureau stratospheric research aircraft M55 Geophysica performed a flight over and within the inner core region of tropical cyclone Davina. Measurements of total water, water vapour, temperature, aerosol backscattering, ozone and tracers were made and are discussed here in comparison with the averages of those quantities acquired during the campaign time frame.
    Temperature anomalies in the tropical tropopause layer (TTL), warmer than average in the lower part and colder than average in the upper TTL were observed. Ozone was strongly reduced compared to its average value, and thick cirrus decks were present up to the cold point, sometimes topped by a layer of very dry air. Evidence for meridional transport of trace gases in the stratosphere above the cyclone was observed and perturbed water distribution in the TTL was documented. The paper discuss possible processes of dehydration induced by the cirrus forming above the cyclone, and change in the chemical tracer and water distribution in the lower stratosphere 400–430 K due to meridional transport from the mid-latitudes and link with Davina. Moreover it compares the data prior and after the cyclone passage to discuss its actual impact on the atmospheric chemistry and thermodynamics.
  • Publication
    Accès libre
    Comparison between Backscatter Lidar and Radiosonde Measurements of the Diurnal and Nocturnal Stratification in the Lower Troposphere
    (2007)
    Martucci, Giovanni
    ;
    Matthey-De-L'Endroit, Renaud 
    ;
    Mitev, Valentin
    ;
    Richner, Hans
    A collection of boundary layer heights has been derived from measurements performed by a ground-based backscatter lidar in Neuchâtel, Switzerland (47.000°N, 6.967°E, 485 m ASL). A dataset of 98 cases have been collected during 2 yr. From these data, 61 are noon and 37 are midnight cases. The following two different schemes were used to retrieve the mixed layer depth and the height of the residual layer from the measurements: the gradient and variance methods. The obtained values were compared with those derived from the potential temperature profiles as computed from radiosonde data. For nocturnal cases, the height of the first aerosol layer above the residual layer was also compared to the corresponding potential temperature value. Correlation coefficients between lidar and radiosonde in both convective and stable conditions are between 0.88 and 0.97.