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@ARTICLE{Griessbach:874614,
author = {Griessbach, Sabine and Hoffmann, Lars and Spang, Reinhold
and Achtert, Peggy and von Hobe, Marc and Mateshvili, Nina
and Müller, Rolf and Riese, Martin and Rolf, Christian and
Seifert, Patric and Vernier, Jean-Paul},
title = {{A}erosol and cloud top height information of {E}nvisat
{MIPAS} measurements},
journal = {Atmospheric measurement techniques},
volume = {13},
number = {3},
issn = {1867-8548},
address = {Katlenburg-Lindau},
publisher = {Copernicus},
reportid = {FZJ-2020-01539},
pages = {1243 - 1271},
year = {2020},
abstract = {Infrared limb emission instruments have a long history in
measuring clouds and aerosol. In particular, the Michelson
Interferometer for Passive Atmospheric Sounding (MIPAS)
instrument aboard ESA's Envisat provides 10 years of
altitude-resolved global measurements. Previous studies
found systematic overestimations and underestimations of
cloud top heights for cirrus and polar stratospheric clouds.
To assess the cloud top height information and to
characterise its uncertainty for the MIPAS instrument we
performed simulations for ice clouds, volcanic ash, and
sulfate aerosol. From the simulation results we found that
in addition to the known effects of the field-of-view that
can lead to a cloud top height overestimation, and broken
cloud conditions that can lead to underestimation, the cloud
extinction also plays an important role. While for optically
thick clouds the possible cloud top height overestimation
for MIPAS reaches up to 1.6 km due to the field-of-view,
for optically thin clouds and aerosol the systematic
underestimation reaches 5.1 km. For the detection
sensitivity and the degree of underestimation of the MIPAS
measurements, the cloud layer thickness also plays a role;
1 km thick clouds are detectable down to extinctions of
5×10−4 km−1 and 6 km thick clouds are detectable
down to extinctions of 1×10−4 km−1, where the largest
underestimations of the cloud top height occur for the
optically thinnest clouds with a vertical extent of 6 km.
The relation between extinction coefficient, cloud top
height estimate, and layer thickness is confirmed by a
comparison of MIPAS cloud top heights of the volcanic
sulfate aerosol from the Nabro eruption in 2011 with space-
and ground-based lidar measurements and twilight
measurements between June 2011 and February 2012. For plumes
up to 2 months old, where the extinction was between
1×10−4 and 7×10−4 km−1 and the layer thickness
mostly below 4 km, we found for MIPAS an average
underestimation of 1.1 km. In the aged plume with
extinctions down to 5×10−5 km−1 and layer thicknesses
of up to 9.5 km, the underestimation was higher, reaching
up to 7.2 km. The dependency of the cloud top height
overestimations or underestimations on the extinction
coefficient can explain seemingly contradictory results of
previous studies. In spite of the relatively large
uncertainty range of the cloud top height, the comparison of
the detection sensitivity towards sulfate aerosol between
MIPAS and a suite of widely used UV/VIS limb and IR nadir
satellite aerosol measurements shows that MIPAS provides
complementary information in terms of detection
sensitivity.},
cin = {JSC / IEK-7},
ddc = {550},
cid = {I:(DE-Juel1)JSC-20090406 / I:(DE-Juel1)IEK-7-20101013},
pnm = {511 - Computational Science and Mathematical Methods
(POF3-511) / 244 - Composition and dynamics of the upper
troposphere and middle atmosphere (POF3-244)},
pid = {G:(DE-HGF)POF3-511 / G:(DE-HGF)POF3-244},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000520409100002},
doi = {10.5194/amt-13-1243-2020},
url = {https://juser.fz-juelich.de/record/874614},
}