Odin/SMR Limb Observations of Stratospheric Trace Gases during 2001-2005

Joachim Urban⁽¹⁾

⁽¹⁾ Chalmers University of Technology, Hörsalsvägen 11, 412 96 Göteborg, Sweden

Abstract

(1) Chalmers University of Technology, Department of Radio and Space Science, 412 96 Göteborg, Sweden.

(2) Observatoire Aquitain des Sciences de l'Univers / L3AB, 33270 Floirac, France.

(3) Swedish Space Corporation, Box 4207, 171 04 Solna, Sweden.

(4) Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden.

(5) Observatoire de Midi-­Pyrénées, Laboratoire d'Aérologie, 31400 Toulouse, France.

(Email: jo.urban@rss.chalmers.se)

Profile measurements of key constituents relevant to stratospheric chemistry and dynamics such as ozone (O3), nitrous oxide (N2O), chlorine monoxide (ClO), and nitric acid (HNO3), taken by the Odin Sub-­Millimetre Radiometer (SMR), are presented.

The Odin/SMR instrument, launched in February 2001 into a polar sun­ synchronous orbit, employs 4 tunable single-sideband­ Schottky-diode heterodyne receivers in the 486-­581GHz spectral range and a 1.1m telescope for passive observations of thermal emissions originating from the Earth's limb. Spectra are recorded using two high resolution auto-­correlator spectrometers. Atmospheric measurements are performed in a time sharing mode with astronomical observations. Profile information is retrieved from the spectral measurements of a limb scan by inverting the radiative transfer equation for a non-­scattering atmosphere.

Stratospheric mode observations are performed approximately on two observation days per week. The characteristics of the recently reprocessed Odin/SMR stratospheric mode level-­2 data (version 2.0) are discussed and the data quality is evaluated by comparison with correlative measurements of other spaceborne instruments such as for example MIPAS on Envisat.

Scientific results are presented with emphasis on measurements taken in the polar winter stratosphere of both hemispheres during the period 2001-­2005. The Odin/SMR measurements of nitrous oxide, chlorine monoxide, nitric acid, and ozone allow to study the chemical and dynamical evolution of the Arctic and Antarctic vortices by providing information on chlorine activation, denitrification, subsidence of vortex air, and on ozone loss.

Odin is a Swedish-­led satellite project funded jointly by Sweden (SNSB), Canada (CSA), Finland (TEKES) and France (CNES).