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| Titel |
ALADINA – an unmanned research aircraft for observing vertical and horizontal distributions of ultrafine particles within the atmospheric boundary layer |
| VerfasserIn |
B. Altstädter, A. Platis, B. Wehner, A. Scholtz, N. Wildmann, M. Hermann, R. Käthner, H. Baars, J. Bange, A. Lampert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 4 ; Nr. 8, no. 4 (2015-04-01), S.1627-1639 |
| Datensatznummer |
250116290
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| Publikation (Nr.) |
 copernicus.org/amt-8-1627-2015.pdf |
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| Zusammenfassung |
| This paper presents the unmanned research aircraft Carolo P360 "ALADINA"
(Application of Light-weight Aircraft for
Detecting IN situ Aerosol) for investigating the
horizontal and vertical distribution of ultrafine particles in the
atmospheric boundary layer (ABL). It has a wingspan of 3.6 m, a maximum
take-off weight of 25 kg and is equipped with aerosol instrumentation and
meteorological sensors. A first application of the system, together with the
unmanned research aircraft MASC (Multi-Purpose Airborne Carrier) of the
Eberhard Karls University of Tübingen (EKUT), is described. As small
payload for ALADINA, two condensation particle counters (CPC) and one optical
particle counter (OPC) were miniaturised by re-arranging the vital parts and
composing them in a space-saving way in the front compartment of the
airframe. The CPCs are improved concerning the lower detection threshold and
the response time to less than 1.3 s. Each system was characterised in the
laboratory and calibrated with test aerosols. The CPCs are operated in this
study with two different lower detection threshold diameters of 11 and 18 nm.
The amount of ultrafine particles, which is an indicator for new particle
formation, is derived from the difference in number concentrations of the two
CPCs (ΔN). Turbulence and thermodynamic structure of the
boundary layer are described by measurements of fast meteorological sensors
that are mounted at the aircraft nose. A first demonstration of ALADINA and a
feasibility study were conducted in Melpitz near Leipzig, Germany, at the
Global Atmosphere Watch (GAW) station of the Leibniz Institute for
Tropospheric Research (TROPOS) on 2 days in October 2013. There, various
ground-based instruments are installed for long-term atmospheric monitoring.
The ground-based infrastructure provides valuable additional background
information to embed the flights in the continuous atmospheric context and is
used for validation of the airborne results. The development of the boundary
layer, derived from backscatter signals of a portable Raman lidar
POLLYXT, allows a quick overview of the current vertical structure
of atmospheric particles. Ground-based aerosol number concentrations are
consistent with the results from flights in heights of a few metres. In
addition, a direct comparison of ALADINA aerosol data and ground-based
aerosol data, sampling the air at the same location for more than 1 h, shows
comparable values within the range of ± 20 %. MASC was operated
simultaneously with complementary flight patterns. It is equipped with the
same meteorological instruments that offer the possibility to determine
turbulent fluxes. Therefore, additional information about meteorological
conditions was collected in the lowest part of the atmosphere. Vertical
profiles up to 1000 m in altitude indicate a high variability with distinct
layers of aerosol, especially for the small particles of a few nanometres in
diameter on 1 particular day. The stratification was almost neutral and two
significant aerosol layers were detected with total aerosol number
concentrations up to 17 000 ± 3400 cm−3 between 180 and 220 m
altitude and 14 000 ± 2800 cm−3 between 550 and 650 m. Apart
from those layers, the aerosol distribution was well mixed and reached the
total number concentration of less than 8000 ± 1600 cm−3. During
another day, the distribution of the small particles in the lowermost ABL was
related to the stratification, with continuously decreasing number
concentrations from 16 000 ± 3200 cm−3 to a minimum of
4000 ± 800 cm−3 at the top of the inversion at 320 m. Above this,
the total number concentration was rather constant. In the region of 500 to
600 m altitude, a significant difference of both CPCs was observed. This
event occurred during the boundary layer development in the morning and
represents a particle burst within the ABL. |
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