1 / 22

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)

tiana
Download Presentation

Institut für Umweltphysik

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related