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@ARTICLE{Beswick:276188,
author = {Beswick, Karl and Baumgardner, Darrel and Gallagher, Martin
and Raga, Graciela B. and Minnis, Patrick and Spangenberg,
Douglas A. and Volz-Thomas, Andreas and Nedelec, Philippe
and Wang, Kuo-Ying},
title = {{P}roperties of small cirrus ice crystals from commercial
aircraft measurements and implications for flight
operations},
journal = {Tellus / B},
volume = {67},
number = {0},
issn = {1600-0889},
address = {Stockholm},
publisher = {Inst.},
reportid = {FZJ-2015-06653},
pages = {27876, 1-22},
year = {2015},
abstract = {Measurements of cloud ice crystal size distributions have
been made by a backscatter cloud probe (BCP) mounted on five
commercial airliners flying international routes that cross
five continents. Bulk cloud parameters were also derived
from the size distributions. As of 31 December 2014, a total
of 4399 flights had accumulated data from 665 hours in more
than 19 000 cirrus clouds larger than 5 km in length. The
BCP measures the equivalent optical diameter (EOD) of
individual crystals in the 5–90 µm range from which size
distributions are derived and recorded every 4 seconds. The
cirrus cloud property database, an ongoing development
stemming from these measurements, registers the total
crystal number and mass concentration, effective and median
volume diameters and extinction coefficients derived from
the size distribution. This information is accompanied by
the environmental temperature, pressure, aircraft position,
date and time of each sample. The seasonal variations of the
cirrus cloud properties measured from 2012 to 2014 are
determined for six geographic regions in the tropics and
extratropics. Number concentrations range from a few per
litre for thin cirrus to several hundreds of thousands for
heavy cirrus. Temperatures range from 205 to 250 K and
effective radii from 12 to 20 µm. A comparison of the
regional and seasonal number and mass size distributions,
and the bulk microphysical properties derived from them,
demonstrates that cirrus properties cannot be easily
parameterised by temperature or by latitude. The seasonal
changes in the size distributions from the extratropical
Atlantic and Eurasian air routes are distinctly different,
showing shifts from mono-modal to bi-modal spectra out of
phase with one another. This phase difference may be linked
to the timing of deep convection and cold fronts that lead
to the cirrus formation. Likewise, the size spectra of
cirrus over the tropical Atlantic and Eastern Brazil differ
from each other although they were measured in adjoining
regions. The cirrus crystals in the maritime continental
tropical region over Malaysia form tri-modal spectra that
are not found in any of the other regions measured by the
IAGOS aircraft so far, a feature that is possibly linked to
biomass burning or dust. Frequent measurements of ice
crystal concentrations greater than 1×105 L−1, often
accompanied by anomalously warm temperature and erratic
airspeed readings, suggest that aircraft often experience
conditions that affect their sensors. This new instrument,
if used operationally, has the potential of providing
real-time and valuable information to assist in flight
operations as well as providing real-time information for
along-track nowcasting.},
organization = {MOZAIC-IAGOS 20th Anniversary
Symposium,},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {243 - Tropospheric trace substances and their
transformation processes (POF3-243) / IAGOS-D - In-Service
Aircraft for a Global Observing System – German
Contribution to the Main Phase of IAGOS
(BMBF-20180331-IAGOSD)},
pid = {G:(DE-HGF)POF3-243 / G:(DE-82)BMBF-20180331-IAGOSD},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000362822200001},
doi = {10.3402/tellusb.v67.27876},
url = {https://juser.fz-juelich.de/record/276188},
}