1. © University of Reading 2008 www.reading.ac.uk 28 June 2015 CAVIAR Experimenters Meeting 2009 Liam Tallis

2. INTRODUCTION 2

3. Lab View 3

4. Sunsets 4

5. Introduction Assessment of the consistency of water vapour lines intensities in recent HITRAN databases Towards an absolute calibration Water Profile for Jungfraujoch Future work 5

6. ASSESSMENT OF THE CONSISTENCY OF WATER VAPOUR LINES INTENSITIES IN RECENT HITRAN DATABASES 6

7. Consistency Assessment Analysis of the consistency of water vapour lines in recent HITRAN databases Similar way to Casanova et. al. (2006) Optical depth spectrum given by Where F m is the measured signal by the FTIR, F s is the extraterestrial irradiance given by Kurucz (1995), τ m is the optical depth, θ is the solar zenith angle and k(v) is an unknown calibration factor. 7

8. Consistency Assessment Rearrangement ignoring the calibration factor (and a few other approximations) We know have a “pseudo” optical depth spectrum This spectrum will allow us to analyse the consistency between observation and model 8

9. Consistency Assessment Optical depth is calculated for water vapour ( τ w ) and for five other principle absorbers in the region: CH 4, CO 2, O 2, N 2 O and O 3 ( τ g ) using RFM (v4.28) Linear fit of the “pseudo” optical depth to that calculated by RFM Fit pseudo to the form of a x τ w + b x τ g + c 9

10. Consistency Assessment a x τ w + b x τ g + c b is tightly bound to be a value between 0.95 to 1.05 – An assumption made is other gases well know – Allowed to vary slightly for any minor error in the column amounts c is allowed to vary more freely – c is a offset parameter that varies slowly with wavelength a is allowed to vary between 0 and 3 – a is the important parameter – tells us the factor line intensities must be multiplied by 10

11. Consistency Assessment 11

12. Consistency Assessment 12

13. Consistency Assessment 13

14. Consistency Assessment Camborne Field Campaign InSb / CaF 2 Typically for 0.03cm-1 resolution spectra Over various days, radiosondes, water columns 14 HITRAN2004HITRAN2008H08 / H04 Average a 1.03321.03751.0055 Average a 3000 cm -1 – 8000 cm -1 0.98230.97830.9961 Average a 8000 cm -1 – 9500 cm -1 1.16141.15790.9971 Average a 10000 cm -1 - 11500 cm -1 0.95600.97621.0233

15. Consistency Assessment 15 HITRAN2004HITRAN2008H08 / H04 Average a 1.03321.03751.0055 Average a 3000 cm -1 – 8000 cm -1 0.98230.97830.9961 Average a 8000 cm -1 – 9500 cm -1 1.16141.15790.9971 Average a 10000 cm -1 - 11500 cm -1 0.95600.97621.0233 Ratio of 3000 cm -1 - 8000 cm -1 to 8000 cm -1 – 9500 cm -1 For HITRAN04 = 0.846, St Dev= 0.011 For HITRAN08 = 0.845, St Dev= 0.010

16. Consistency Assessment Camborne Field Campaign MCT / KBr Problems! Fit appears to be good... But scaling factor required for water vapour lines feels wrong Typical “a” value ~ 0.7 16

17. Consistency Assessment Camborne Field Campaign MCT / KBr Typically for 0.03cm -1 resolution spectra Over various days, radiosondes, water columns 17 HITRAN2004HITRAN2008H08 / H04 Average a 700 cm -1 – 1400 cm -1 0.75 0.99 Average a 800 cm -1 – 1000 cm -1 0.810.780.96 Average a 1100 cm -1 - 1250 cm -1 0.760.740.97

18. Consistency Assessment 18

19. Consistency Assessment 19

20. Consistency Assessment 20

21. TOWARDS AN ABSOLUTE CALIBRATION 21

22. Towards an Absolute Calibration Calibrations before each field campaign at NPL NPL produce a calibration function which when used with spectral data gives an irradiance [W/m2/FT o/p unit] Calibration x Spectral Data = Calibrated Spectra Extraterrestrial irradiance given by Kurucz’s (1995) database 22

23. Towards an Absolute Calibration 23

24. Towards an Absolute Calibration 24

25. Towards an Absolute Calibration We know the signal measured by the FT is given by And thus by rearranging, we can work out the optical depth 25

26. Towards an Absolute Calibration 26

27. Towards an Absolute Calibration 27

28. Towards an Absolute Calibration 28

29. Towards an Absolute Calibration 29

30. Towards an Absolute Calibration Microtops II Sunphotometer 13/08/2008 AOT380 = 0.465, AOT440 = 0.486, AOT675 = 0.577, AOT936 = 0.705, AOT1020 = 0.608 Campaign Average AOT380 = 0.22, AOT440 = 0.17, AOT675 = 0.12, AOT936 = 0.09, AOT1020 = 0.08 30

31. Towards an Absolute Calibration 31

32. Towards an Absolute Calibration 32

33. WATER PROFILE FOR JUNGFRAUJOCH 33

34. Water Profile for Jungfraujoch 34 Radiosonde (Payerne) Dropsonde (FAAM) FAAM Aircraft GPS IWV ECMWF Forecast Fields STARTWAVE Database, University of Bern – GPS Water Vapour – Column Water from Payerne Radiosonde

35. Water Profile for Jungfraujoch 35

36. Water Profile for Jungfraujoch 36

37. Water Profile for Jungfraujoch 37 1 st August 2009

38. FUTURE WORK 38

39. Future Work Analysis of the consistency of water vapour lines in recent HITRAN databases – Any improvements to MCT fit possible? – Repeat this style analysis for Jungfraujoch – Try with new ACE-FTS extraterrestrial line list (Hase et. al, JQSRT 2009) Absolute Calibration – Account for difference between calibrated spectra and extraterrestrial irradiance (in atmospheric windows) – Use Reading’s RFM + DISORT Code Water Profile for Jungfraujoch – Continued work in this area Questions? 39