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Institut für Umweltphysik

Ground-based passive remote sensing measurements of H 2 O at Spitsbergen and Suriname Justus Notholt, Mathias Palm (FTIR), Harry Küllmann (MW) University of Bremen Matthias Schneider (FTIR) IMK/FZK, Karlsruhe Christian Mätzler (MW) University of Bern Bing Tan (MW)

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Institut für Umweltphysik

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  1. Ground-based passive remote sensing measurements of H2O at Spitsbergen and Suriname Justus Notholt, Mathias Palm (FTIR), Harry Küllmann (MW) University of Bremen Matthias Schneider (FTIR) IMK/FZK, Karlsruhe Christian Mätzler (MW) University of Bern Bing Tan (MW) University of Suriname, Paramaribo Universität Bremen Institut für Umweltphysik

  2. Observations in Spitsbergen/Ny-Ålesund (78,9°N)

  3. H2O total columns above Ny-Ålesund sonde lunar solar 30 IWV (kg m-2) or (mm) water vapour (molec. cm-2) 15 0 date (dd.mm.yy)

  4. Retrieval with SFIT-2 solar spectra • Frequency range: 823.5 – 827.0 cm-1 • Channeling: 4 sinusoidial structures • Interfering gases: O3 (profile retrieval), CO2, C2H6 (column retrieval)‏ • Solar lines included • logarithmic state vector for H2O, normalised state vector for anything else • diagonal covariance matrix • SNR ~ 150 : 1 – 500 : 1 • constant a priori lunar spectra • Frequency range: 3 microwindows in 780 - 800 cm-1 • No channeling • Interfering gases: O3, CO2 (column retrieval)‏ • normalised state vector • diagonal covariance matrix • SNR ~ 50 : 1 – 100 : 1 • Constant a priori

  5. Lunar observations sonde FTIR 12 water vapour (molec. cm-2) IWV (kg m-2) or (mm) 6 0 date (dd.mm.yy) - atmospheric emission up to 40% - full radiative transfer in SFIT-2 (absorption + emission in transmission spectra)

  6. Zoom in lunar observations sonde FTIR 7,50 water vapour (molec. cm-2) IWV (kg m-2) or (mm) 3,75 0,00 date (dd.mm.yy)

  7. Natural variability of H2O coli – coli-1 x 100 (%) coli-1 average variability from day-to-day: 37±45% variability date (dd.mm.yy)

  8. Variability of H2O within a day sonde FTIR 4,0 IWV (kg m-2) or (mm) 3,0 1.0 2,0

  9. Ny-Ålesund measurements evaluated with IMK retrieval: PROFFIT v9.4 (on logarithmic scale)

  10. + zero baseline, channeling, and phase error correction

  11. + zero baseline, chaneling, and phase error correction + set of modified line parameters

  12. → also for artic measurements at sea level sensitivity above 10km !

  13. Sensitivity of profile retrieval Subtropics Arctic altitude (km) altitude (km) DOF: 3.20 DOF: 3.02 AVK AVK - SFIT-2 - same Sa matrix - log retrieval - different vmr-profiles → averaging kernels depend on assumed vmr → vmr profile depends on tropopause altitude → maximum altitude of profile retrieval depends on tropopause altitude → maximum altitude of profile retrieval of H2O below tropopause (?)

  14. profile retrieval > 3 km sonde FTIR 0,6 0,0 water vapour (molec. cm-2) IWV (kg m-2) or (mm) 0 – 3 km 3,0 sonde FTIR 0,0 date (dd.mm.yy) - SFIT-2 - log- retrieval - constant a-priori

  15. log-retrieval <-> linear retrieval log-retrieval lmr = ln (vmr) vmr = elmr t(n) ~ e-elmr → non linear dependance linear retrieval t(n) ~ e-vmr → non linear dependance lin log - water variability is log-normal distributed (all trace gases are log-normal distributed) - retrieval often more stable - for small absorption features positive bias transmission ~ vmr

  16. TARA (Tragbares Radiometer) in Suriname (5,8°N) measurements - Integrated Water Vapor (IWV) - Integrated Liquid Water (ILW) channels (20.9 GHz and 35.0 GHz) Intermediate frequency (IF) 10-400 MHz Dicke switching (@ 70 Hz) to eliminate gain fluctuations location Suriname, Paramaribo, 5,8°N 56°W (since December 2006) Partners Institute of Applied Physics, University of Bern Faculty of Technology University of Suriname

  17. Meteorological Service of Suriname

  18. 21 March 2007 (good day)  calibration wrong for IWV

  19. 1 November 2007 (bad day) Problems - dew on window at night [1] - rain hits window [2] - temperature sensor in shadow but heated from below vapor (IWV) - slow decrease in the morning - sudden rise shortly after noon Liquid water (ILW)- clouds in morning [3] and at noon [2] Improvements - window heating - other temperature measurements - rain protection - more frequent calibrations 2 3 3 1 2 1

  20. Comparison with AMMA-observations, 9.6°N, 1.4°E (Crewell, University of Bonn) http://www.amma-germany.de/doku.php/quicklooks_h

  21. climatology seasonal variability in 2007 250 200 150 100 50 0 Tmin, Tmax (K) IWV (arb. units) RHmin, RHmax (%) 0 50 100 150 200 250 300 350 day of 2007 precipation (mm) month of year

  22. Summary FTIR observations in high Arctic - FTIR allows total column retrieval with sufficient accuracy - lunar observations give accurate total columns - suitable for trend studies - profile retrieval up to tropopause 2 channel MW observations in tropics - MW-observations in tropics successfully started - mechanical modifications required high resolution MW observations in tropics (Merida) - measurements throughout whole year in 2007 - channeling - study of tape recorder

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