The backscatter cloud probe – a compact low-profile autonomous optical spectrometer
A compact (500 cm<sup>3</sup>), lightweight (500 g), near-field, single particle backscattering optical spectrometer is described that mounts flush with the skin of an aircraft and measures the concentration and optical equivalent diameter of particles from 5 to 75 μm. The backscatter cl...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-05-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/7/1443/2014/amt-7-1443-2014.pdf |
| Summary: | A compact (500 cm<sup>3</sup>), lightweight (500 g), near-field, single particle
backscattering optical spectrometer is described that mounts flush with the
skin of an aircraft and measures the concentration and optical equivalent
diameter of particles from 5 to 75 μm. The backscatter cloud probe
(BCP) was designed as a real-time qualitative cloud detector primarily for
data quality control of trace gas instruments developed for the climate
monitoring instrument packages that are being installed on commercial
passenger aircraft as part of the European Union In-Service Aircraft for a
Global Observing System (IAGOS) program (<a href="http://www.iagos.org/"target="_blank">http://www.iagos.org/</a>).
Subsequent evaluations of the BCP measurements on a number of research
aircraft, however, have revealed it capable of delivering quantitative
particle data products including size distributions, liquid-water content and
other information on cloud properties. We demonstrate the instrument's
capability for delivering useful long-term climatological, as well as
aviation performance information, across a wide range of environmental
conditions.
<br><br>
The BCP has been evaluated by comparing its measurements with those from
other cloud particle spectrometers on research aircraft and several BCPs are
currently flying on commercial A340/A330 Airbus passenger airliners. The
design and calibration of the BCP is described in this article, along with an
evaluation of measurements made on the research and commercial aircraft.
Preliminary results from more than 7000 h of airborne measurements by the
BCP on two Airbus A340s operating on routine global traffic routes (one
Lufthansa, the other China Airlines) show that more than 340 h of cloud data
have been recorded at normal cruise altitudes (> 10 km) and
more than 40% of the > 1200 flights were through clouds at
some point between takeoff and landing. These data are a valuable
contribution to databases of cloud properties, including sub-visible cirrus,
in the upper troposphere and useful for validating satellite retrievals of
cloud water and effective radius; in addition, providing a broader,
geographically and climatologically relevant view of cloud microphysical
variability that is useful for improving parameterizations of clouds in climate
models. Moreover, they are also useful for monitoring the vertical climatology of
clouds over airports, especially those over megacities where pollution
emissions may be impacting local and regional climate. |
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| ISSN: | 1867-1381 1867-8548 |