Clouds at the tropical tropopause: a case study during the APE-THESEO campaign over the western Indian Ocean (Articolo in rivista)

Type

• Prodotto della ricerca (Classe)
• Articolo in rivista (Classe)

Label

• Clouds at the tropical tropopause: a case study during the APE-THESEO campaign over the western Indian Ocean (Articolo in rivista) (literal)

Anno

• 2003-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

• 10.1029/2002JD002166 (literal)

Alternative label

• Santacesaria, Vincenzo; Carla, Roberto; MacKenzie, Robert; Adriani, Alberto; Cairo, Francesco; Didonfrancesco, Guido; Kiemle, Christoph; Redaelli, Gianluca; Beuermann, Jürgen; Schiller, Cornelius; Peter, Thomas; Luo, Beiping; Wernli, Heini; Ravegnani, Fab (2003)
  Clouds at the tropical tropopause: a case study during the APE-THESEO campaign over the western Indian Ocean
  in Journal of geophysical research
  (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

• Santacesaria, Vincenzo; Carla, Roberto; MacKenzie, Robert; Adriani, Alberto; Cairo, Francesco; Didonfrancesco, Guido; Kiemle, Christoph; Redaelli, Gianluca; Beuermann, Jürgen; Schiller, Cornelius; Peter, Thomas; Luo, Beiping; Wernli, Heini; Ravegnani, Fab (literal)

Pagina inizio

• 4044 (literal)

Pagina fine

• AAC-14 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

• 108 (literal)

Rivista

• Journal of geophysical research (Rivista)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#descrizioneSinteticaDelProdotto

• The study analyizes the formation and maintenance of cirrus clouds at the tropical tropopause. During the first flight of APE-THESEO campaign, a thin cirrus with a relatively high optical thickness of 0.1 was observed. The lidar ratio, estimated by using the LIDAR data together with the thermal IR Meteosat radiances, was equal to 117-130 sr. This value is compatible with cloud particles composed of small plate-like, or cylindrical, ice crystals. Apparently, this observation is different from those reported by others. In fact, it is not easy to fit this Ci into the classification they have indicated according to the Ci near the tropopause. According to its high altitude, the present cloud should belong into class II cirrus clouds. However, it was not found directly downstream of deep convection. Rather, we have shown that the present Ci cannot be considered to be anvil outflow, because of the low altitude reached by the Cbs in the western Indian Ocean at this time. A first strong decrease in the water vapor content is observed across the lower limit of the TTL at 14-15 km, followed by a slower decrease and a minimum at the tropopause. The dehydration potential of the observed Ci is high. We have measured roughly 2 ppmv (at 18 km) of water condensed in the cloud particles. Simple microphysical argumentation, based on T-matrix computations, suggests that the observed ice particles had an average radius around 5 ¼m and were aspherical, with an aspect ratio ranging from 0.5 to 0.7 (literal)

Note

• ISI Web of Science (WOS) (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

• 1 IFAC-CNR; 2 Environ. Science Dept.,Lancaster, Univ.,UK ; 3 ISAC-CNR; 4 Deutsches Zentrum fur Luft und Raumfhart,DE; 5 Università dell’Aquila; 6 Forschungszentrum Jqlich, DE; 7 Inst. for Atmos. and Clim. Science, SW; 8 Central Aerological Observatory, Russia; 9 APE Srl., IT; 10 ENEA. (literal)

Titolo

• Clouds at the tropical tropopause: a case study during the APE-THESEO campaign over the western Indian Ocean (literal)

Abstract

• In this paper, we report a detailed description of a thin cirrus at the tropopause above a cumulonimbus (Cb) convective cluster observed during the Airborne Platform for Earth Observation-Third European Stratospheric Experiment for Ozone (APE-THESEO) campaign in February-March 1999 in the western Indian Ocean. The thin cirrus (Ci) has an optical depth at 532 nm below 0.1, with extended subvisible stretches, and is located directly below the tropopause, which was supersaturated with respect to ice. A direct comparison between the optical depth retrieved by Meteosat and that obtained by means of the hygrometers installed on the M55-Geophysica aircraft is discussed showing discrepancies ranging from 10 to 20%. Combining satellite and aircraft data, we show that the observed Ci is not due to cirrus outflow from Cb anvils. In the absence of any deeply convective clouds reaching altitudes above 15 km, we propose a possible mechanism of Ci formation based on a net mesoscale transport of water vapour from altitudes above 16 km to the tropopause region around 18 km. This transport could be driven by the critical layer and turbulence induced by gravity waves that could have been generated by lower level Cb cluster activity. The proposed mechanism for high-altitude Ci formation corroborates the new paradigm of a tropical tropopause layer (TTL) or \"substratosphere\", several kilometers thick, which is decoupled from the convection-dominated lower troposphere. (literal)

Prodotto di

• Institute of atmospheric sciences and climate (ISAC) (Istituto)
• Institute of applied physics \"Nello Carrara\" (IFAC) (Istituto)

Autore CNR

• FRANCESCO CAIRO (Unità di personale interno)
• ROBERTO CARLA' (Persona)
• LEOPOLDO STEFANUTTI (Persona)
• FABRIZIO RAVEGNANI (Persona)
• ALBERTO ADRIANI (Unità di personale interno)

Insieme di parole chiave

• Parole chiave di "Clouds at the tropical tropopause: a case study during the APE-THESEO campaign over the western Indian Ocean" (Insieme di parole chiave)

Incoming links:

Prodotto

• Institute of atmospheric sciences and climate (ISAC) (Istituto)
• Institute of applied physics \"Nello Carrara\" (IFAC) (Istituto)

Autore CNR di

• ROBERTO CARLA' (Persona)
• FABRIZIO RAVEGNANI (Persona)
• FRANCESCO CAIRO (Unità di personale interno)
• ALBERTO ADRIANI (Unità di personale interno)
• LEOPOLDO STEFANUTTI (Persona)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#rivistaDi

• Journal of geophysical research (Rivista)

Insieme di parole chiave di

• Parole chiave di "Clouds at the tropical tropopause: a case study during the APE-THESEO campaign over the western Indian Ocean" (Insieme di parole chiave)