Overview and quality of global observations of middle atmospheric water vapour by the Odin satellite

Transcription

1 Overview and quality of global observations of middle atmospheric water vapour by the Odin satellite J. Urban*, D.P. Murtagh*, M. Ekström,, P. Eriksson*, C. Sanchez*, A. Jones,* S. Lossow **, Y. Kasai ***, E. Dupuy****, K. Walker **** and the Odin/SMR team * Department of Radio and Space Science, Chalmers University of Technology, Göteborg G / Sweden * * Meteorological Institute of Stockholm University / Sweden *** National Institute for Information and Communications Technology, Tokyo / Japan **** University of Toronto, Canada

2 SPARC 2001 water 1-10 hpa assessment Direct comparisons cluster within a 10% range in middle and upper stratosphere hpa Over 20% differences not uncommon in the lower stratosphere. 10% Extreme range of direct comparisons exceeds 30% hpa Indirect comparisons differ by as much as 50%. NEW H2O ASSESSMENT IN ! From SPARC H 2 O Assessment, Figure 2.73

3 The Odin satellite Swedish led mini-satellite. Cooperation with Canada, Finland, France. Launched in February Design lifetime: 2 years. Circular quasi-polar sun-synchronous orbit: ~600km altitude, 96min/orbit, 6h/18h equator crossing. Time sharing: 50% astronomy, 50% aeronomy 100% aeronomy since April 2007! Limb-sounding in aeronomy mode: ~45-65 scans/orbit, ~15 orbits per day. 2 instruments: SMR (Sub-Millimetre Radiometer), OSIRIS (Optical Spectrograph and InfraRed Imaging System) Science objectives: stratospheric and mesospheric processes

4 Middle atmosphere Odin aeronomy science objectives: Chemical and dynamical processes related to stratospheric ozone, Spatial and temporal variability of water vapour and its isotopes in the middle atmosphere, Global circulation and the transport between the spheres global circulation CO, N 2 O, H 2 O, T water isotopes (H 2 O, HDO, H 2 O-18, H 2 O-17) (O 3, O 3-18-asym, O 3-18-sym, O 3-17-asym) summer mesosphere H 2 O, O 3, CO, T odd nitrogen NO, HNO 3 stratospheric mode ClO, N 2 O, HNO 3, O 3,, (H 2 O, ice)

5 Odin/SMR frequency coverage water isotope mode (H 2 O, HDO, H 2 O-18, H 2 O-17) (O 3, O 3-18-asym, O 3-18-sym, O 3-17-asym) odd nitrogen mode (NO, HNO stratospheric mode 3 ) (ClO, N 2 O, HNO 3, O 3 ) odd hydrogen / summer mesosphere mode (H 2 O, O 3, CO, HO 2 ) Swedish Space Corporation 485GHz 580GHz

6 Odin/SMR water vapour observation modes band species days/month altitude region range GHz H2O ~4 (8) mesosphere, lower therm. ~ km GHz H2O, H2O-18 ~4 (8) stratosphere, mesosphere ~20-75 km GHz HDO ~4 (8) stratosphere, mesosphere ~20-70 km GHz H2O (3) stratosphere, mesosphere ~20-75 km GHz H2O ~10 (15) lower stratosphere ~10-25 km 501.8/544.6 GHz RHi, IWC ~10 (15) tropical upper troposphere ~10-15 km

7 Lower stratospheric water vapour

8 H GHz: : 2003 H2O retrieval from continuum emissions in GHz stratospheric mode measurements (O3, HNO3), ~10 observation days per month. Global coverage (~83S-83N), altitude resolution ~3-4 km, useful altitude range ~10-25 km covering UT/LS, noise requires averaging. Monthly zonal mean fields: - Large VMR in troposphere, change of gradient indicates tropopause, -Typical VMR in lower stratosphere (~15-25km) of ppmv, -De-hydrification inside Antarctic polar vortex: Very low values at km in SH winter (~Jul-Nov), - Minima around ~20-25 km at high latitudes (summer hemisphere and outside vortex during winter).

9 H2O: Odin/SMR vs ACE/FTS Lower stratospheric water vapour 544.6GHz band, mode SM_AC1e

10 H2O-cont 544.6GHz tape-recorder

11 Tropical ascent rates heating rates, trajectories [Wohltmann & Rex ACPD, 2007] Odin/SMR HALOE: 2[CH4]+[H2O] [Hall & Waugh JGR, 1997] Odin/SMR average consistent with HALOE! [J. Urban, Proc. Reunion Island Symp., 2007]

12 Water isotopes in stratosphere and mesosphere

13 Odin/SMR Water Isotope Mode: H 2 O, O 3 + isotopes GHz band tropics GHz band ~ 20 km H 2 O-16 HDO H 2 O-18 O 3-16 ~ 35 km O 3-18-sym O 3-18-asym O 3-17-asym O 3 -img ~ 50 km Chalmers-v2.1

14 Odin/SMR water isotope mode Retrieved profiles of H GHz and GHz H 2 16 O (0.3S/106.5E) tropics HDO (4.2S/129.9E) Simultaneous retrieval of H 2 16 O, O 3, H 2 18 O / HDO, 18 O 3 -asym, 18 O 3 -sym, scan-bias, linear baseline (offset), temperature, and continuum Chalmers-v2.1

15 H 2 O Odin/SMR water isotope mode Sep-Oct-Nov H 2 18 O HDO Isotopic depletion/enrichment: δd = (R obs /R ref 1) x 100 [%] e.g. Standard Mean Ocean Water: D/H ratio = R ref = x10-4 Isotopic fractionation processes: phase changes, chemistry Chalmers-v2.1 δ 18 O(H 2 O) δd (H 2 O)

16 Comparison with 2-d 2 d model: H 2 O, HDO, δd Zonal mean of water vapour H 2 16 O and its isotopologue HDO ( ) H GHz H GHz GHz GHz δd (HDO) δd (HDO) 2-d model / DJF 2-d model / DJF SMR / DJF SMR / DJF 2d-model from Ridal & Siskind calculations C. Sanchez

17 H2O: Odin/SMR vs ACE/FTS Strato-mesospheric water vapour 489GHz band, mode IM_AC2ab

18 HDO zonal mean: ACE/FTS vs Odin/SMR 70 20ºS-20ºN 30ºN-60ºN 70ºN-90ºN FTS SMR 60 FTS SMR 60 FTS SMR Eric Dupuy, Univ. Toronto DJF MAM JJA SON DJF MAM JJA SON DJF MAM JJA SON VMR [ppbv] VMR [ppbv] VMR [ppbv]

19 H GHz 21 km 36 km 50 km

20 Strato-mesospheric H 2 O-17 / 2007 Jan Jul Apr Oct Chalmers-v2.1 H GHz

21 Mesospheric water vapour

22 Mesospheric water GHz 51 km 65 km 79 km

23

24 H2O: Odin/SMR vs ACE/FTS Mesospheric water vapour 557GHz band, mode IM_AC1c

25 Mesospheric water vapour / 2002 Jan Jul Apr Oct Chalmers-v2.1 H GHz

26 Annual and semi-annual oscillations Odin/SMR H 2 O@557GHz high latitudes 80 S S. Lossow tropics 10 S - 10 N

27 Water vapour evolution Example: 83 km altitude Sunspot number Odin S. Lossow

28 Summary Odin carrying SMR (Sub-Millimetre Radiometer) launched in February 2001 now: ~6 years of observations starting from Nov 2001 (quasi-global coverage). Continued operation through (ESA third party mission, 100% aeronomy). Odin/SMR water vapour measurement modes: 1. Mesospheric water vapour: H 2 O, O 3, T at 557GHz: ~4 days / month, Nov , mesosphere (~50-100km), now ~8 days / month 2. Strato-mesospheric water vapour and its isotopes: H 2 O, HDO, H 2 O-18, O 3 -isotopes around 490GHz: ~4 days / month, Nov , strato+mesosphere (~20-75km), now ~8 days / month H 2 O-17, NO, O 3, T at 551GHz: ~1 day / month, Oct , strato+mesosphere (~18-75km), now ~4 days / month 3. Lower stratospheric water vapour and upper tropospheric humidity: N 2 O, ClO, O 3, HNO 3,T, ~10 days / month, Nov , stratosphere (~100hPa-1hPa), 1hPa), now ~15 days / month water retrieval from stratospheric mode continuum emissions. Odin/SMR operational level-2 data: Chalmers-v2.0/v2.1, processed up to date.

29 Next steps... New reprocessing of L1b- and L2-data for main stratospheric and water isotope modes envisaged in Eliminate some known problems (attitude data inconsistency, calibration issues, spectroscopy...) Ongoing quality assessment of water vapour products: Comparisons (e.g. ACE, MLS, MIPAS, MOSAIC, sondes, NDAAC) Identify biases and artefacts... Unify Odin H2O data product(s): Correction of biases, data filtering Data assimilation... Model studies, model comparisons (2-d, 3-d 3 d CTM / CCM) Trends?

30 Water vapour time series NH: 30-60ºN 35-45km VMR / ppmv SAGE HALOE POAM Odin/SMR AURA/MLS year courtesy of Ashley Jones, Chalmers

31 Thank you!