APE-THESEO (anciennement TRACES)

• Research unit: EU RFP
• Project number: 97.0436

Key words (English)

Troposphere; Stratosphere; Aerosol; Clouds; Airborne Aerosol lidar

Alternative project number (English)

EU project number: ENV4-CT97-0533

Research programs (English)

EU-programme: 4. Frame Research Programme - 3.1 Environment

Short description (English)

See abstract

Partners and International Organizations (English)

CNR (I), University of Cambridge (UK), MPI for Chemistry (D), University of Rome (I), University of Mainz (D), University of Frankfurt (D), University of Stockholm (S), University of L'Aquila (I), CAO (RU), Aviaecocentre (RU), DLR (D)

Abstract (English)

The objective of the project APE-THESEO is to investigate how strong convection activity affect the particles and trace gases in the high tropical troposphere and lower stratosphere. In particular the study targeted the distribution, the microphysical properties and the content of the particles in cirrus clouds, the content of water and trace gases in the high troposphere and lower stratosphere and their flux through the tropopause. The importance of these issues is determined by their role in the equilibrium of the global stratospheric ozone layer.
The project APE-THESEO organised a mission with the high-altitude research aircraft 'Geophysica' M-55 in the Inter Tropical Convergence Zone in Indian Ocean. The project combines on the high-altitude research aircraft 'Geophysica' M-55 a payload of instruments for in situ measurements and remote sensing of the properties of the aerosol particles, the content of water, ozone, HNO3 and some important trace gases. The project also benefited from the flights by lower altitude aircraft with long range lidar parallel to M-55 flights. The mission site was Seychelles, Indian Ocean. There were total of 7 research flights in the mission in the period mid February-mid March 1999.
In APE-THESEO the Observatory of Neuchâtel (ON) participated with a short range depolarisation/backscatter lidar, named MAL (Miniature aerosol lidar). This is a compact automated lidar installed on M-55 for probing at zenith, operating at wavelength of 532nm. Its technical detection range for this mission was 2.5km, the practical one was up to 0.5-1 km from the aircraft. The lidar detected visible and sub visible (tropopause) Ci (2nd and 3rd flights) and Ci and Cb ( 6th flight - cyclone Davina).
In the frame of OFES project APE-THESEO ON took part in the mission APE-GAIA in Antarctic. APE-GAIA is an Italian project (supported by ENEA and PRNA) targeting the composition of the Antarctic stratosphere during the recovery phase in the early Spring. The mission was carried during September-October 1999 from Ushuaia-Argentine. It involved with a few exceptions, the same partners as APE-THESEO. ON participated with two lidars, similar to the one in APE-THESEO but with increased detection range, one was mounted for probing at zenith, the second - for probing at nadir, operating simultaneously.
During one flights above Antarctic Peninsula the lidars detected a massive PSC event coinciding with the lee-wave forecast done for this flight. Another flight indicated also a minor PSC coinciding with a variation of the temperature typical for wave activity. These results indicate the probability for Spring time lee-wave PSC appearance and to the possibility by this for prolongation of the time for the ozone destruction chemical reaction .

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0436