Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Clouds at the tropical tropopause: a case study during the APE-THESEO campaign over the western Indian Ocean.
AU - Santacesaria, Vincenzo
AU - Carla, Roberto
AU - MacKenzie, A. Robert
AU - Adriani, Alberto
AU - Cairo, Francesco
AU - Didonfrancesco, Guido
AU - Kiemle, Christoph
AU - Redaelli, Gianluca
AU - Beuermann, Jürgen
AU - Schiller, Cornelius
AU - Peter, Thomas
AU - Luo, Beiping
AU - Wernli, Heini
AU - Ravegnani, Fabrizio
AU - Ulanovsky, Alexey
AU - Yushkov, Vladimir
AU - Sitnikov, Nikolay
AU - Balestri, Stefano
AU - Stefanutti, Leopoldo
N1 - It describes research carried out using the Geophysica research aircraft. MacKenzie was Scientific Coordinator for this campaign, and closely collaborated on the analysis and final manuscript. This paper records much of the work that led to MacKenzie, Peter, and Stefanutti being short-listed for the 2001 Italgas Prize. RAE_import_type : Journal article RAE_uoa_type : Earth Systems and Environmental Sciences
PY - 2003/1/1
Y1 - 2003/1/1
N2 - 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 vapor 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.
AB - 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 vapor 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.
U2 - 10.1029/2002JD002166
DO - 10.1029/2002JD002166
M3 - Journal article
VL - 108
SP - 4044
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 0747-7309
IS - D2
ER -