270 likes | 415 Views
Odin/SMR Limb Observations of Stratospheric Trace Gases during 2001-2006. J. Urban, D. Murtagh, J. Rösevall, N. Lauti é, A. Jones, P. Eriksson, M. Olberg, … Department of Radio and Space Science, Chalmers University of Technology, 412 96 Göteborg / Sweden E. Dupuy, J. de La Noë, …
E N D
Odin/SMR Limb Observations of Stratospheric Trace Gases during 2001-2006 J. Urban, D. Murtagh, J. Rösevall, N. Lautié, A. Jones, P. Eriksson, M. Olberg, … Department of Radio and Space Science, Chalmers University of Technology, 412 96 Göteborg / Sweden E. Dupuy, J. de La Noë, … Observatoire Aquitain des Sciences de l’Univers, L3AB, Floirac / France P. Ricaud, E. Le Flochmoën, B. Barret, … Laboratoire d’Aérologie, Toulouse / France … and the Odin/SMR instrument team … and various contributors to the validation
The Odin satellite • Swedish led mini-satellite. • Cooperation with Canada, Finland, France. • Launched in February 2001. • Design lifetime: 2 years. • Circular quasi-polar sun-synchronous orbit: • 625km altitude, 96min/orbit, • 6h/18h equator crossing. • Time sharing: 50% astronomy, 50% aeronomy. • Limb-soundingin aeronomy mode: • ~45-65 scans/orbit, ~15 orbits per day. • 2 instruments: • SMR (Sub-Millimetre Radiometer), • OSIRIS(Optical Spectrograph and InfraRed Imaging System) • Aeronomy science objectives: stratosphere + mesosphere. • stratospheric mode (ClO, N2O, HNO3, O3),water isotope mode (H2O, HDO, H2O-18, H2O-17), • odd hydrogen / summer mesosphere mode (H2O, O3, CO),odd nitrogen mode (NO, HNO3, NO2 )
Odin/SMR frequency coverage Swedish Space Corporation odd nitrogen mode (NO, HNO3 ) water isotope mode (H2O, HDO, H2O-18, H2O-17) (O3, O3-18-asym, O3-18-sym, O3-17-asym) odd hydrogen / summer mesosphere mode (H2O, O3, CO) stratospheric mode (ClO, N2O, HNO3, O3)
Odin/SMR aeronomy data processing Retrieval Sweden (operational data) Retrieval France (reference version)
Odin/SMR Stratospheric Mode: N2O, ClO, O3, HNO3 HNO3 20-Sep 2002 Antarctic polar vortex - 78.4S/143.8E ~ 18 km N2O O3 N2O ~ 25 km O3 ClO 544.6 GHz band 501.8 GHz band ~ 32 km ~ 40 km CTSO-v223-offline
Odin/SMR stratospheric mode: level 2 product / zonal mean O3 N2O ClO 501.8 GHz band 20-21 March 2003 O3 HNO3 544.6 GHz band
Odin/SMR validation update: N2O Available N2O data versions: Chalmers-v1.2 (→April 2005), Chalmers-v2.0 (operational processor) http://www.rss.chalmers.se/gem CTSO-v222 (reference version) http://www.ether.ipsl.jussieu.fr
Level 2 quality assessment N2O: results balloon + aircraft MIPAS – v4.61/ofl ILAS-II (v1.4) Ch v1.2 Ch v2.0
Odin/SMR N2O: 2003 Jan Feb Mar May Jun Apr Jul Aug Sep Oct Nov Dec • Consistency of broad morphological features with previous global data-sets (Nimbus-7/SAMS;UARS/CLAES, UARS/ISAMS), • better global and altitude coverage of Odin/SMR (~83S-83N; ~1-100 hPa). • maximum VMR in tropical lower stratosphere, decreasing with altitude. • transport out of the tropics towards winter hemisphere following seasonal variation (Brewer-Dobson circulation). • Particular features: • - steep gradients at high-latitudes of winter hemispheres (subsidence • inside polar vortices), • - flat “surf-zone” equator-ward of vortex in zonal mean fields, • - “double-peak” structure in tropics at 5-10 hPa during Apr-Jun, also visible in Nov 2002 (in contrast to SAMS and CLAES). 25-26 September 2003 [Urban et al., JGR 2005]
Odin/SMR validation update: HNO3 Available HNO3 data versions: Chalmers-v1.2 (→April 2005), Chalmers-v2.0 (operational processor) http://www.rss.chalmers.se/gem CTSO-v223 (reference version) (not systematically produced)
Level 2 quality assessment HNO3: results balloon + aircraft MIPAS – v4.61/ofl ILAS-II (v1.4) Ch v1.2 Ch v2.0
Odin/SMR HNO3: 2003 Jan Feb Mar May Jun Apr Jul Aug Sep Oct Nov Dec HNO3 Chalmers-v2.0 • Consistency of broad morphological features e.g. with UARS/MLS climatology [Santee, JGR 2004], • Good altitude resolution (~2km) and global coverage (~83S-83N) of Odin/SMR, but limited altitude range at bottom (~1-50 hPa). • Minimum VMR in tropics, increasing VMR towards higher latitudes. • Maximum in lower stratosphere (~20-25km). • Seasonal variation with maxima in autumn (NH: ~Oct-Dec; SH: ~Apr-Jun). • Particular features: • - Very low values in lower stratosphere of southern winter hemisphere (denitrification inside Antarctic polar vortex ~Jun-Nov), • - Second maxima at ~30-40 km at high latitudes during winter [plot: M. Pommier]
Polar processes: Antarctic winter 2004 @ 475K T N2O ClO SZA O3 HNO3 Chalmers-v1.2
Antarctic winter 2004: vortex means Chalmers-v2.0 T-ECMWF [K] Vortex coldest in ~July z [km] Subsidence (weakens in August) Tpot [K] ClO [ppbv] Chlorine activation: ClO depends strongly on solar zenith angle. May-Aug → night-time measurements, Sep-Oct → day-time measurements SZA O3 [ppmv] Ozone loss, starting in August, strongest in September O3 [ppmv] Removal of HNO3 from gas phase starting in June – complete in July HNO3 [ppbv]
Polar processes: Arctic winter 2004-05 @ 475K T N2O ClO SZA O3 HNO3 Chalmers-v1.2
Arctic winter 2004-05: vortex means Chalmers-v2.0 T-ECMWF [K] Vortex coldest in Dec-Jan z [km] Subsidence (Nov - mid Feb) Tpot [K] ClO [ppbv] Chlorine activation: ClO depends strongly on solar zenith angle. Nov-Feb → night-time measurements, Mar-Apr → day-time measurements SZA O3 [ppmv] “Weaker” ozone loss in Jan+Feb O3 [ppmv] Low HNO3 (temporary removal from gas phase) during short episodes in December + January. HNO3 [ppbv]
Data assimilation:ozone loss + horizontal transportArctic winter 2004-05 • DIAMOND model (Chalmers University, Göteborg): • transport on isentropic surfaces • ECMWF wind fields • N2O and O3 from Odin/SMR 501.8 GHz data / version 2.0 • [J. Rösevall, D. Murtagh et al., 2006]
Polar processes: Arctic winter 2005-06 @ 475K Chalmers-v2.0 T N2O ClO O3 HNO3
Arctic winter 2005-06: vortex means Chalmers-v2.0 T-ECMWF [K] Vortex cold during Dec, warming in Jan z [km] Subsidence (Dec + Jan) Tpot [K] ClO [ppbv] High night-time ClO in relatively warm mid-January vortex indicates chlorine activation from reservoir gases. SZA O3 [ppmv] No obvious ozone loss in Dec-Jan O3 [ppmv] HNO3: No obvious removal from gas-phase HNO3 [ppbv]
Odin/SMR: strato-mesospheric water vapour Retrieval of water vapour H216O - band 488.35-489.35 GHz 15 Dec 2001 - zonal mean and global distribution zonal mean H216O H216O at 30km Roughly 4 observation days per month since November 2001: 24 hours = ~14 orbits x ~50 scans / orbit [N. Lautie et al., 2003]
Summary • Odin carrying SMR (Sub-Millimetre Radiometer)launched in February 2001 • now: ~4.5 years of observations starting from Nov 2001 (quasi-global coverage). • Odin just got green light for continued operation until April 2007. • Stratospheric and mesospheric research objectives (aeronomy mode): • Stratospheric chemistry and dynamics (e.g. polar processes, global circulation) • Strato-mesospheric water vapour and its isotopes (e.g. sources of water vapour) • Mesospheric measurement modes (e.g. global circulation, summer-mesosphere) • Odin/SMR stratospheric mode data of ClO, N2O, HNO3, O3 analysed up to ~ January 2006 (Chalmers-v2.0). • Level-2 data access: Operational data: http://www.rss.chalmers.se/gem → Chalmers-v1.2, Chalmers-v2.0 Reference versions: http://ether.ipsl.jussieu.fr → Bdx-v222 / Bdx-v223 • Reprocessing of L1b- and L2-datafor main stratospheric and water isotope modes ongoing during 2006 (→Ch-v2.0, Ch-v2.1), incl. processing of mesospheric water vapour.