MOZAIC 1994 - ongoing

Official MOZAIC homepage

Brief description

The MOZAIC programme (Measurement of OZone and water vapour by AIrbus in-service airCraft) was initiated in 1993 by European scientists, aircraft manufacturers and airlines (Air France, Sabena, Austrian Airlines and Lufthansa) to collect experimental data. Its goal is to help understand the atmosphere and how it is changing under the influence of human activity, with particular interest in the effects of aircraft. MOZAIC consists of automatic and regular measurements of ozone and water vapour by five long range passenger airliners flying all over the world. MOZAIC III now also includes measurements of carbon monoxide and nitrogen oxides.

Special remarks concerning TRADEOFF database content

For MOZAIC flights both fmt files (complete flights) and airport profiles were processed. Fmt-files were processed to 12 min averages. Since this results in a poor vertical resolution during take-off and landing also the profile files were included in the database. Profiles were averaged over 3 consequtive levels, i.e. to a vertical resolution of 450 m. Profile files are not necessarily in chronological order and therefore no time stamp is given. However, we assume a linearly changing time between the start and end of the profile which is indicated in the header.

The following parameters were included both in the fmt andthe profile data files:

O3 (ppb)

Specific humidity Q (g/kg)

Relative Humidity Quality Flag. QF(). 1=ok, 2=below detection limit, 3=not very good, 0=no data

Relative Humidity Error. E(%). Note: Relative Humidity and specific humidity are connected through Goff & Gratch (1946).

T(K)

Overview of measurement techniques and uncertainties

(1) Ozone measurements LA/CNRS (Toulouse)
The ozone analyzer is a dual beam UV absorption instrument (Thermo-Electron, Model 49-103). Much care is taken to control the quality of the measurements. A Teflon KNF Neuberger pump is used for pulling air through the analyzer, from the external pressure of 150-250 mbar at cruise altitude. In these conditions, the characteristics of ozone measurements by MOZAIC are the following: detection limit 2 ppbv, overall precision ± [2 ppbv + 2%]. This corresponds to an upper limit of the error on the measurements, and studies of MOZAIC data have in fact shown better characteristics.

(2) Water vapour measurements FZJ (Jülich)
For water vapor, a special airborne humidity sensing device (AD-FS2), developed by Aerodata (Braunschweig, Germany) and based on the humidity and temperature transmitter HMP 230 of Vaisala (Helsinki, Finland), is used for measuring relative humidity and temperature of the atmosphere. The sensing element itself is a combination of a capacitive relative humidity sensor (Humicap-H, Vaisala) and a Pt100-temperature sensor which have been installed in an appropriate housing (Model 102-BX, Rosemount, United States), mounted near the ozone inlet pitot tube. Before installation in the A340, and after every 500 hours of flight operation, each water vapour sensing unit is calibrated in the environmental simulation chamber in FZJ/Jülich. The calibrations have shown that the sensor is reliable for measurements of relative humidity from the surface up to the upper troposphere.

References

"First Results from the MOZAIC-1 Program" special section, JGR, Vol. 103, No. D19, 1998.

For further references see MOZAIC homepage