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@ARTICLE{Spang:154218,
author = {Spang, R. and Günther, G. and Riese, M. and Hoffmann, L.
and Müller, Rolf and Griessbach, S.},
title = {{S}atellite observations of cirrus clouds in the {N}orthern
{H}emisphere lowermost stratosphere},
journal = {Atmospheric chemistry and physics / Discussions},
volume = {14},
number = {8},
issn = {1680-7375},
reportid = {FZJ-2014-03597},
pages = {12323 - 12375},
year = {2014},
abstract = {Here we present observations of the Cryogenic Infrared
Spectrometers and Telescopes for the Atmosphere (CRISTA) of
cirrus cloud and water vapour in August 1997 in the upper
troposphere and lower stratosphere (UTLS) region. The
observations indicate a considerable flux of moisture from
the upper tropical troposphere into the extra-tropical
lowermost stratosphere (LMS), resulting in the occurrence of
high altitude optically thin cirrus clouds in the LMS.The
locations of the LMS cloud events observed by CRISTA are
consistent with the tropopause height determined from
coinciding radiosonde data. For a hemispheric analysis in
tropopause relative coordinates an improved tropopause
determination has been applied to the ECMWF temperature
profiles. We found that a significant fraction of the cloud
occurrences in the tropopause region are located in the LMS,
even if a conservative overestimate of the cloud top height
(CTH) determination by CRISTA of 500 m is assumed. The
results show rather high occurrence frequencies $(∼5\%)$
up to high northern latitudes (70° N) and altitudes well
above the tropopause (>500 m at ∼350 K and above) in large
areas at mid and high latitudes.Comparisons with model runs
of the Chemical Lagragian Model of the Stratosphere (CLaMS)
over the CRISTA period show a reasonable consistency for the
retrieved cloud pattern. For this purpose a limb ray tracing
approach was applied through the 3-D model fields to obtain
integrated measurement information through the atmosphere
along the limb path of the instrument. The simplified cirrus
scheme implemented in CLaMS seems to cause a systematic
underestimation in the CTH occurrence frequencies in the LMS
with respect to the observations. The observations together
with the model results demonstrate the importance of
isentropic, quasi-horizontal transport of water vapour from
the sub-tropics and the potential for the occurrence of
cirrus clouds in the lowermost stratosphere and tropopause
region.},
cin = {IEK-7 / JSC},
ddc = {550},
cid = {I:(DE-Juel1)IEK-7-20101013 / I:(DE-Juel1)JSC-20090406},
pnm = {411 - Computational Science and Mathematical Methods
(POF2-411)},
pid = {G:(DE-HGF)POF2-411},
typ = {PUB:(DE-HGF)16},
doi = {10.5194/acpd-14-12323-2014},
url = {https://juser.fz-juelich.de/record/154218},
}