Cloud Property Measurements from Commercial Aircraft

Measurements from commercial airliners with a compact (500 cm3), lightweight (500 g), near-field, single particle backscattering optical spectrometer are presented. The BCPt 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 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 (http://www.iagos.org/). We show the instrument's capability for delivering useful long-term climatological, as well as aviation performance information, across a wide range of environmental conditions.

Several BCPs are currently flying on commercial A340/A330 Airbus passenger airliners. Preliminary results from more than 10,000 hours of airborne measurements by the BCP on three Airbus A-340s operating on routine global traffic routes (Lufthansa, Air France and China Airlines) show that more than 500 hours of cloud data have been recorded at normal cruise altitudes (> 10 km) and more than 40% of the >2000 flights were through clouds at some point between takeoff and landing. These data are a valuable contribution to data bases of cloud properties, including sub-visible cirrus, in the upper troposphere and useful for validating satellite retrievals of cloud water and effective radius as well as providing a broader, geographically and climatologically relevant view of cloud microphysical variability useful for improving parameterizations of clouds in climate models. They are also useful for monitoring the vertical climatology of clouds over airports, especially those over mega-cities where pollution emissions may be impacting local and regional climate.