SAONAS: Stratospheric aerosol and ozone measurements at middle and high latitudes in the northern and southern hemisphere

• Research unit: EU RFP
• Project number: 95.0294

Key words (English)

Lidar; stratosphere; stratospheric aerosol; PSC (Polar Stratospheric Clouds); atratospheric temperature

Alternative project number (English)

EU project number: ENV4-CT95-0090

Research programs (English)

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

Short description (English)

See abstract

Partners and International Organizations (English)

Sodankylä Meterological Observatory/FMI, Sodankylä (FIN); IROE/CNR, Florence (I), University of Aquila, l'Aquila (I), Free University of Berlin (D), University of Lyon (F), University of Oslo (N), Service d'Aéronomie/CNRS, Paris (F), IFA/CNR, Frascati (I)

Abstract (English)

SAONAS network co-ordinated stratospheric lidar backscatter measurements and data processing with 7 backscatter lidars in sites at different latitudes. The depolarisation-backscatter lidar for operation in the Observatory of Sodankylä (Finnish Meteorological Institute), Sodankylä - Finland (67N), was part of this network. It was developed in 1996 by the Observatory of Neuchâtel (ON) and was built in cooperation with LPAS-DGR/EPFL (the Swiss contractor in the EU project is ON with EPFL/DGR as subcontractor). The Sodankylä lidar detected Polar Stratospheric Clouds (PSC) stratospheric background aerosol and Rayleigh backscatter signal for stratospheric temperature retrieval. The organisation of the measurements was as intensive campaigns during the winters of 1996/97,1997/98 and 1998/99. The operation during 1998/99 was possible due to 6 months extension of SAONAS in the frame of the European THESEO Campaign.

The available data base of PSC observation obtained during the 3 winters of operation identified total of 4 types of PSC events. Those included a liquid particles PSC, observed previously also above Sodankylä. For several case studies the PSC event were characterised in connection to the air-mass temperature history from trajectory analysis. The observations revealed a variability of the PSC appearance, with minimum during 1998/1999.

The data base of observation of the background stratospheric aerosol is combined from the lidars participating in SAONAS network, including the Sodankylä lidar. The decline of the background stratospheric aerosol after the Pinatubo eruption in 1991 is clearly seen and the 'aerosol decay time constant' was evaluated.

The data processing for stratospheric temperature was a task of ON only. It consisted of temperature profile retrieval between app. 25 and 55 km, evaluation of the systematic and the statistical errors, comparison with the temperature measured by PTU radiosondes (when available). The stratospheric temperature profile shows appearance of cold periods and stratospheric warming events.

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: 95.0294