Ground based UV/vis observations

Transcription

1 Ground based UV/vis observations A) History B) Spectroscopy C) Basic viewing directions D) Radiative transport modelling E) Results from different stations 1

2 Remote sensing in UV / vis spectral range Cloud droplets rain droplets aerosols molecules Wavelengths from ~3 to 7nm -electronic + vibrational transitions => Emission can be neglected 2

3 William Hyde Wollaston Philosophical Transactions of the Royal Society of London, vol. 92 (182), p. 38 (Plate XIV) ,5 m -Wollaston verwendet statt rundem Loch einen dünnen Spalt (1.3 mm) -er entdeckt 7 schwarze Linien, 5 davon hält er für Grenzen zwischen natürlichen Farben 3

4 Anfänge der Spektroskopie Joseph von Fraunhofer ( ) Ich fand mit dem Fernrohre fast unzählig viele starke und schwache vertikale Linien, die aber dunkler sind als der übrige Teil des Farbbildes; einige scheinen fast schwarz zu sein erste große achromatische Objektive für Fernrohre erste Verwendung von Beugungsgittern, erste absolute Wellenlängenbestimmung Bestimmung der Position von 234 der über 5 von ihm gefundenen Linien im Sonnenspektrum; seine Benennung wird heute noch Verwendet Von Joseph von Fraunhofer selbst koloriertes Sonnenspektrum, um

5 Gustav Robert Kirchhoff in Heidelberg: Robert Wilhelm Bunsen in Heidelberg: , in Berichten der Preußischen Akademie der Wissenschaften: Über die Fraunhoferschen Linien: Kochsalzdampf absorbiert auch dieselben von ihm emittierten Linien; diese sind mit den Fraunhoferlinien in der heißen Sonnenatmosphäre identisch. 5

6 Ozon Wirkungsquerschnitt 188, Hartley: UV Ozonabsorption [cm ] 1E-17 1E-18 1E-19 1E-2 1E-19 1E-2 1E-21 1E , Chappuis: vis Ozonabsorption 189, Huggins 1E-21 1E-22 1E-23 Liniengruppe Spektrum des Sirius (langwellige UV Absorption des Ozon) Hartley Huggins Chappuis Wavelength [nm] 6

7 Basic viewing geometries: Direct light: Sun, Moon, Stars -easy geometry -nightime measurements Direktlicht- Beobachtungen Zenit SZA Zenith scattered sun light: -sensitive to stratospheric trace gases Vom Zenit gestreute Intensität Scattered sun light in various viewing directions (MAXDOAS): -sensitive to tropospheric trace gases Sun Spectrograph Zenith Stratosphere Troposphere

8 1925: Dobson-Spekrophotometer zur Messung der Ozonschichtdicke 8

9 9

10 O3-Absorptionsquerschnitt [cm ] 3E-19 2E-19 1E-19 A B C D E Wellenlänge [nm] Dobson-Photospektrometer Das Intensitätsverhältnis verschiedener Wellenlängenpaare hängt von der Ozongesamtsäule ab 1 Dobson Unit (DU) entspricht einer Säule von 1 m unter Normalbedingungen Typische Ozonschichtdicke: 35 DU (3.5 mm unter N.B.) 1

11 UV / vis remote sensing (of the earth s atmosphere) A modified Brewer instrument was used to measure the atmospheric NO 2 absorptions [cm²] 1E-18 8E-19 6E-19 4E-19 2E-19 NO 2 cross section (22K) Vandaele et al., 1997 Brewer et al., Nature, 1973, Uni-Toronto 1E-18 8E Wavelength [nm] E-19 F log I log1 I 2 I I 2 3 [cm²] 4E-19 2E Wavelength [nm]

12 Absorption spectroscopy Beer- Lambert-law : Optical depth l I( ) I ( ) exp i ( ) i ( s) s ( ) ds i i : i : s : Absorption cross section of trace gas i Concentration of trace gas i Extinction coefficient => From the knowledge of the absorption cross section it is possible to determine the trace gas concentration 12

13 Differential absorption spectroscopy Beer- Lambert-law : Differential optical depth l I( ) I' ( ) exp ' i ( ) i ( s i ) ds I i : Intensity minus all broad and contributions (absorption & scattering) i : Differential absorption cross section of trace gas i i : Concentration of trace gas i s : Extinction coefficient => From the knowledge of the differential absorption cross section it is possible to determine the trace gas concentration 13

14 Intensit t I( ) Meßspektrum 'differentielle' optische Dichte I O3-Absorption I c ln I I' l ' Typically the light path length l is not known NO2-Absorption Wellenlänge [nm] SCD c s ' 14 I I '

15 6 % 7 % 7 % Atmospheric spectrum Divided by Sun Spectrum Ring Spectrum Example of a DOAS analysis of scattered sun light (from satellite measurements).3 % BrO Target species: BrO 1.2 % O3 2.2 %.2 % O4 Residual From spectral fit => Trace gas SCD Wavelength [nm] 15

16 O O , SZA: Optical density NO , SZA: OClO , SZA: NO 2 OClO Examples of different trace gas analyses (ground based measurements at Kiruna, northern Sweden) BrO , SZA: Wavelength [nm] Examples of the spectral fitting procedure of the different trace gases (data from the Kiruna instrument). Displayed are the absorption cross sections (red curves) scaled to the respective trace gas absorption in the measured spectrum (black curves). BrO 16

17 Differentielle Wirkungsquerschnitte verschiedener atmosphärischer Spurengase '[1-19 cm 2 ] O 3 Phenol SO 2 1 HCHO 2 ClO 5 BrO Benzol 1 5 Toluol 8 4 para-kresol HONO NO Wavelength [nm] 17 IO NO2 Detection Limit 1 ppb L=5km 5 ppt L=5km 2 ppt L=5km 1 ppt L=5km 5 ppt L=5km 5 ppt L=5km 2 ppt L=12km 2 ppt L=12km 1 ppt L=16km 2 ppt L=1km 25 ppt L=1km 5 ppt L=1km 2 ppt L=1km

18 General strategy for UV / vis observations: two step approach: a) Spectroscopy (spectral fit) => yields the integrated trace gas concentration along the light path, the so called slant column density, SCD b) Radiative transfer simulations => converts the SCD into the vertical column density, the vertically integrated trace gas cincentration This separation is possible because a) usually the absorptions in the UV/vis are weak b) only absorption (no emission) has to be considered (in principle also the general retrieval approach, e.g. Optimal Estimation, could be applied) 18

19 Direct light observations -light source: sun, moon or star -direct light path, easy interpretation of the measurement (similar to long path DOAS) -complex instrumental set-up, tracking system -night-time chemistry can be investigated 19

20 Der 'Air-Mass-Faktor' (AMF) Zenit Direktlicht- Beobachtungen SZA Quotient aus schräger und vertikaler Säulendichte: AMF = SCD / VCD 1 / cos (SZA) SCD: entlang des Lichtstrahls integrierte Spurenstoffkonzentration VCD: entlang der Vertikalen integrierte Spurenstoffkonzentration 2

21 The AMF depends on the altitude of the trace gas profile Stratospheric trace gas layer Trop. trace gas layer Direct light AMF for different (box) profile height 6 AMF profile height (x km - x+1 km) geometric AMF SZA 21

22 Intensity [arbitr. units] Stratospheric DOAS-measurements A / B: C: reference spectrum O3 B: SZA=65 degrees spectra measured at different solar zenith angles A: SZA=9 degrees Two measurements are needed to remove the Fraunhofer lines: One measurement at low SZA (with weak atmospheric absorptions) and one at high SZA (with strong atmospheric absorptions) Direktlicht- Beobachtungen Zenit SZA D: reference spectrum O => only differences! Wavelength [nm] 22

23 Direktlicht- Beobachtungen Zenit SZA ref mess The measured SCD is the difference between both measurements: SCD = SCD mess SCD ref = VCD * AMF mess VCD * AMF ref => VCD = SCD / (AMF mess - AMF ref ) 23

24 O3-Langley-Plot 1 Fit: Y = 356DU * X - 454DU SCD O3[DU] SCD 5 Slope = VCD y-intercept => SCD ref AMF VCD = SCD / AMF VCD = (SCDmess + SCDref) / AMF Dmess + SCDref) / AMF VCD = ( SCD SCD SCDmess = (VCD * AMF) - SCDref 24

25 Kiruna, 25./26.Jan 1994 VCD NO3 [113molec/cm ] Direct moonlight measurements 4 VCD NO2 [115 molec/cm ] VCD NO2 night VCD NO2 day 1/25/94 4:48 1/25/94 16:48 1/26/94 4:48 1/26/94 16:48 Zenith scattered sunlight measurements 25

26 Stickoxidgleichgewicht Photolyse NO NO 2 N 2 O 5 schnelles Gleichgewicht langsame Gleichgewichte HNO 3 Diurnal cycle of reactive nitrogen compounds. N 2 O 5 is accumulated during night and photolised during day. Thus NO 2 is systematically smaller during sunrise than during sunset [Lambert et al., 22]. 26

27 Zenith scattered light observations -simple instrumental set-up -restricted to daylight -high sensitivity for stratospheric trace gases -often complicated data analysis, radiative transfer simulation is required 27

28 Spectroscopy of zenith scattered light Vom Zenit gestreute Intensität Sensitivity: -is high for low sun (large solar zenith angle, SZA) (sensitivity for stratosphere is higher than for direct light observations) -depends on many parameters: -wavelength -concentration profile -aerosol profile -clouds => Radiative transfer modelling is required 28

29 Dependence of the AMF on SZA and surface albedo 14 1/cos(SZA) 12 1 strat. AMF, albedo: 8% & 5% AMF 8 6 trop. AMF, albedo: 8% trop. AMF, albedo: 5% SZA [ ] 29

30 Monte Carlo Radiative transfer models (e.g. MCARTIM, Tim Deutschmann) - individual photon paths are modelled -atmospheric processes like scattering and absorption and also surface reflection are simulated statistically - advantages: - full 3D geometry - most realistic simulation of the reality - disadvantages: - computational expensive 3

31 MCARTIM, Tim Deutschmann Deutschmann et al

32 satellite Example of radiative transfer modelling for satellite nadir geometry, 37 nm, no clouds Look from the side Rayleigh-scattering ground reflection TRACY-II Tim Deutschmann, IUP Heidelberg Look from above 32

33 satellite Example of radiative transfer modelling for satellite nadir geometry, 37 nm, with cloud (OD 4) from the surface to 8 km Look from the side Rayleigh-scattering ground reflection particle scattering TRACY-II Tim Deutschmann, IUP Heidelberg Look from above 33

34 Realistic modelling of microscopic cloud properties: Backward Monte Carlo modelling Photon paths for different aerosol phase functions Green points indicate scattering points of photons => reception area of the detector Strong forward peak aerosol layer Instrument Suniti Sanghavi, IUP Heidelberg Moderate forward peak aerosol layer Instrument 34 Tim Deutschmann, IUP Heidelberg

35 Simulated Intensity.12 no aerosols Normalised Radiance Reihe1 42 nm (blue) Reihe2 5 nm (green) Reihe3 6 nm (red) Elevation angle , 4:1 The sky is bright close to the horizon AOD:.1 Normalised Radiance Reihe1 42 nm (blue) Reihe2 5 nm (green) Reihe3 6 nm (red) Elevation angle 35

36 AMF calculation from simulated radiances 1) The atmospheric properties for a given measurement (e.g. the SZA, the trace gas profile, etc.) are defined. 2) The intensity is modelled for two cases: with (I) and without (I ) the absorbing species. From the calculated intensities the corresponding optical density for the trace gas SCD is determined: SCD I ln I 3) The ratio of this optical density and the absorption cross section for the selected trace gas absorption yields the trace gas SCD: SCD SCD 4) The trace gas profile defined in the first step is integrated to yield the respective VCD. The AMF is determined from the SCD and VCD according to the AMF-equation : AMF = SCD / VCD 36

37 Raman scattering on air molecules (Ring effect) Transitions for rotational and vibrational Raman scattering on O 2 and N 2 molecules 37

38 Filling-in of Fraunhofer lines by inelastic scattering (Ring effect) In the UV spectral range the corresponding spectral features accound for up to 1% optical depth earth shine spectrum dirct sun light spectrum intensity [arbitrary units] Wavelength [nm] 38

39 Fig.Sample Ring spectrum (I( Ring )) calculated for the evaluation of UV spectra taken during ALERT2. Shown is also the logarithm of the Fraunhofer reference spectrum(i meas ) used for the calculation. 39

40 6 % 7 % Atmospheric spectrum Divided by Sun Spectrum Example of a DOAS analysis of scattered sun light (from satellite measurements) Ring spectrum 7 % Ring Spectrum.3 % BrO Target species: BrO 1.2 % O3 2.2 % O4.2 % Residual Wavelength [nm] 4

41 Time series from zenith sky observations at different locations Overview on the Heidelberg network of ground based DOAS stations. The instrument at Paramaribo (Suriname) was build and installed within the project. Kiruna Paramaribo Neumayer Arrival Heigts MAXDOAS Jan-1 Jan-2 Jan-3 Jan-4 Jan-5 Periods of successful measurements. The Paramaribo measurements started in May 22. In early the instrument at the Neumayer station was equipped with a MAXDOAS telescope.

42 Instrumental set-up at Kiruna. Three spectrometers are mounted on a high table directly below the plexiglass dome. The controlling devices are placed below. The telescope lenses for the three spectrometers are mounted on a common frame over which a black shielding or a halogen lamp is automatically moved during night. These measurements are important for the calibration of the instrument and the correction of dark current and electronic offset (Bugarski, 23). 42

43 O3-Auswertung O3-Fitergebnis SCD O3 [DU] 8 Optische Dichte [rel. Einheiten] 4 Tagesgang, Kiruna, SCD O3 VCD O3 [DU] VCD O3 4:48 7:12 9:36 12: 14:24 16:48 Zeit 43

44 NO 2 -Auswertung Optische Dichte [rel. Einheiten] NO2-Fitergebnis Wellenlänge [nm] SCD NO2 [1e15 molec/cm ] Tagesgang, Kiruna, SCD NO2 VCD NO2 [1e15 molec/cm ] VCD NO2 7:12 9:36 12: 14:24 Zeit 44

45 Stickoxidgleichgewicht Photolyse NO NO 2 N 2 O 5 schnelles Gleichgewicht langsame Gleichgewichte HNO 3 Diurnal cycle of reactive nitrogen compounds. N 2 O 5 is accumulated during night and photolised during day. Thus NO 2 is systematically smaller during sunrise than during sunset [Lambert et al., 22]. 45

46 8.E+15 7.E+15 VCD Average NO2 VCD from SCIAMACHY at noon Reihe2 MAXDOAS NO2 VCD sunrise 9 SZA Reihe3 MAXDOAS NO2 VCD sunset 9 SZA 6.E+15 NO2 VCD [molec/cm²] 5.E+15 4.E+15 3.E+15 2.E+15 1.E+15.E+ SCIAMACHY NO2 VCD Andreas Richter Nov. 96 Nov. 97 Nov. 98 Nov. 99 Nov. Nov. 1 Nov. 2 Nov. 3 Nov. 4 Time Time series of NO 2 VCDs measured by the Kiruna instrument since December From 22 to 25 also the time series of average SCIAMACHY NO 2 VCDs (within 2km, scientific product of the University of Bremen) are shown. 46

47 8.E+15 7.E+15 6.E+15 Minimum VCDmin NO2 VCD from SCIAMACHY at noon MAXDOAS Reihe2 NO2 VCD sunrise 9 SZA MAXDOAS Reihe3 NO2 VCD sunset 9 SZA SCIAMACHY NO2 VCD Andreas Richter NO2 VCD [molec/cm²] 5.E+15 4.E+15 3.E+15 2.E+15 1.E+15.E+ Jan. 5 Feb. 5 Mrz. 5 Apr. 5 Mai. 5 Jun. 5 Time series of NO 2 VCDs measured by the Kiruna instrument and minimum SCIAMACHY NO 2 VCDs (within 2km, scientific product of the University of Bremen) for the first half of 25. The SCIAMACHY NO 2 VCDs are between the Kiruna AM and PM data probably indicating remaining low NO 2 contributions from the troposphere. 47 Time

48 Time series of NO 2 VCDs measured by the Kiruna instrument between January 1997 to December 214. In addition satellite results (GOME-1, SCIAMACHY, GOME-2) analysed by the University of Bremen are shown. Myojeong Gu, MPIC Mainz 48

49 Long time series allow to investigate trends... Paul Johnston, Richard Querel (NIWA), personal communication 49

50 Telescope Observation platform Quartz glass fiber bundles Top: Building of the meteorological service of Suriname in Paramaribo. The telescopes of the MAXDOAS instrument are seen at the top. Right: The telescope units outside the building are connected to the spectrometers inside via glass fibre bundles. Spectrograph UV Spectrograph Visible Electronics Meteorological Office Building Computer 5

51 4.E E+15 SCIAMACHY NO2 VCD Andreas Richter 3.E+15 NO2 VCD [molec/cm²] 2.5E+15 2.E E+15 1.E+15 5.E+14.E+ Min VCDmin NO2 VCD from SCIAMACHY at noon MAXDOAS Reihe2 NO2 VCD sunrise 9 SZA MAXDOAS Reihe3 NO2 VCD sunset 9 SZA Apr. 2 Okt. 2 Apr. 3 Okt. 3 Apr. 4 Okt. 4 Apr. 5 Time Time series of NO 2 VCDs measured by the Paramaribo instrument and minimum SCIAMACHY NO 2 VCDs (within 2km, scientific product of the University of Bremen) for the period

52 Dynamical and photochemical development in the stratosphere during polar winter Surface reactions Gas phase reactions Abundance ClONO2 HCl ClO + 2 Cl2O2 Fall Early winter Late winter Spring Time Denitrification Dehydration End of polar night photochemical ozone destruction Transport hv (UV) PSC BrO CFC Stratosphere Reservoir compounds active comp. OClO (HCl, ClONO 2 ) (Cl, ClO) Ozone destruction 52

53 During polar night a vortex formes in the stratosphere. No effective mixing appears between air inside and outside this polar vortex. vironment-book/images/polarvortex.jpg f_record_ozone_loss_arctic_wide_measurements_verify_rapid_depletion_in_ recent/?chash=ee2ef56ededac781aeddcb73f26bdc 53

54 High values of OClO (indicating stratospheric chlorine activation) are found only when the polar vortex is over Kiruna. 54

55 3. E +1 4 OClO DSCD [molec/cm²] 2.5 E E E E E +1 3 KR iruna e ihe 1O C lo D SC D A M KR iruna e ihe 2O C lo D SC D P M OClO DSCDs over Kiruna for different polar winters. High values were detected for the cold winters 1999/2 and 24/25.. E E +1 3 Jan. Ja n. 1 Jan. 2 Ja n. 3 Jan. 4 Jan. 5 Tim e Volume of polar stratospheric clouds and Ozone loss for different Antarctic winters ( Markus Rex, see Strong ozone destruction was observed during the winters with high chlorine activation indicated by high OClO DSCDs over Kiruna 55

56 DOAS- Messungen auf der Neumayer- Station/Antarktis Udo Frieß VCD O 3 [DU] DOAS (84 <=SZA<=9 ) DOAS (88 <=SZA<=94 ) Ozone soundings TOMS VCD NO 2 [1 15 molec/cm 2 ] am pm Date hPa [K] Date SCD OClO [1 14 molec/cm 2 ] am, SZA = 9 pm, SZA = 9 am, SZA = 94 pm, SZA = K (PVU) Date

57 Absorptionserhöhung durch Bewölkung Effects of clouds II -clouds enhance the light path inside the cloud Mie-Vielfach-Streuung Spektrograph 57

58 intensity [counts] 2E+6 1E+6 E+ B: A: cloudy sky ( , SZA: 85.4 ) clear sky ( , SZA: 85.5 ) Quotient A / B 3 2 A 2 C = A / B B 1 Quotient C / Polynomial wavelength [nm] O4 H2O 58

59 Average [1/s] nm 3E+4 2E+4 1E+4 Intensität Thick cloud over Kiruna, Intensit tsquotient 682nm / 388 nm E E-3 Colour-Index VCD NO 2 klarer Tag klarer Tag OD 5E-4 OD OD E SCD H 2 O Diff. SCD O 4 The strongest absorption enhancement occurs when a very thick cloud waslocated over the measurement site (low intensity). 6 Trop. O 3 Absorption [DU] 3 7:12 9:36 12: 14:24 Zeit 59

60 Multi-Axis Observation Geometry Sun Zenith Stratosphere 45 Scattered light measurements in different viewing directions (close to the horizon to the zenith) Zenith sky measurements are sensitive mainly to the stratospheric column Spectrograph Troposphere Measurements close to the horizon have a long light path through the troposphere and are therefore sensitive for trace gases near the surface Multi-Axis DOAS allows to gain information on the vertical distribution of atmospheric trace gases 6

61 Compact (Mini) MAX-DOAS instrument The whole instrument is turned by stepper motor Advantages: - rather cheap, commercially available - simple operation (only battery and notebook needed) Mini-MAX-DOAS during the CINDI campaign, Cabauw, The Netherlands, 29 Disadvantages: - poor spectral quality - low quantum efficiency in UV - often problems with USB connection Hoffmann Messtechnik, Germany 61

62 Advanced MAX-DOAS set-up spectrometer inside moveable telescope outside two-axis sun tracker Clemer et al., AMT 21 62

63 Three azimuth directions are observed simultaneously Three UV spectra on the CCD Same azimuth angle Different azimuth angles 63 Wagner et al., AMT 211

64 High-speed 2-D MAX-DOAS instruments moveable telescope with strong & precise motor Similar instruments are used by Uni Colorado Uni Heidelberg AIOFM Hefei BIRA Brussels 64

65 MAX-DOAS observations at Milano, 23 For (mainly) stratospheric Absorbers (e.g. O 3 ) all elevation angles yield the same DSCDs 3 1.E+2 O4 DSCD O3 DSCD Altitude [km] 2 1 O3 O3 DSCD [molec/cm²] 8.E+19 6.E+19 4.E+19 Reihe1 3 elevation angle Reihe2 6 Reihe3 1 Reihe E+19.E+ 4: 6:24 8:48 11:12 13:36 16: The U-shape is caused by the changing SZA 65

66 MAX-DOAS observations at Milano, 23 For surface-near Absorbers (e.g. HCHO) all elevation angles yield different DSCDs Altitude [km] HCHO4 SCD HCHO [molec/cm²] 1.E+17 8.E+16 6.E+16 4.E+16 Reihe 3 Reihe Reihe 1 Reihe 18 Elevation: Reihe1 3 Reihe2 6 6 Reihe3 1 Reihe E+16.E+ 4: 6:24 8:48 11:12 13:36 16: Time

67 Altitude [km] For Absorbers located also in the free troposphere (e.g. the oxygen dimer O 4 ) the difference between the DSCDs is small MAX-DOAS observations at Milano, 23 O4 O4 DSCD [14molec2/cm5] The U-shape is caused by the changing SZA elevation angle O4 DSCD Reihe2 18 Reihe3 1 Reihe4 6 Reihe5 3 4: 6:24 8:48 11:12 13:36 16:

68 Increasing aerosol optical depth O4 DSCD [1 4 molec 2 /cm 5 ] Telescope elevation Reihe Reihe2 Reihe3 Reihe4 Reihe5 Reihe O4 AMF (reference added) 14. Sep. 15. Sep. 16. Sep. 17. Sep. Date Increasing aerosol laod leads to a decreas of the absorption paths and thus to a decrease of the measured absorptions. => From MAX-DOAS measurements aerosol profiles can be inverted => Only after aerosol profiles are known, trace gas profiles can be inverted

69 How to derive profiles (trace gases and aerosols) from measured DSCDs? -compare results from forward model to measurements -iterate assumed profiles until forward model and measurements agree -information content is limited (typically 1-3 pieces of information) -Optimal estimation and parameterised inversion algorithms are used 69

70 Forward model: A) aerosol or trace gas profile B) Radiative transfer model Trace gas DSCDs altitude DSCD Concentration MCARTIM (T. Deutschmann) 3D spherical MC model - Raman scattering - Polarisation Elevation angle 7

71 S =.5 S =.8 S = 1. S = 1.2 S = 1.2 linear two layers Trace gas concentration or aerosol extinction We use simple parameterisation (1-3 independent pieces of information) for tropospheric profiles: -layer height -shape factor -vertically integrated amount (trace gas VCD or AOT) 71

72 Comparison of measured O 4 DAMFs (black dots) to the results of the forward model (coloured lines) O 4 damf , 12: 19.9., 8: Reihe1 Measurement Reihe2 S = 1.1 Reihe9 S = 1. Reihe8 S =.8 Reihe3 S = 1.1 (linear) Elevation angle [ ] O 4 damf Reihe1 Measurement Reihe2 S = 1.1 Reihe9 S = 1. Reihe8 S =.8 Reihe3 S = 1.1 (linear) Elevation angle [ ] : : f: 1.1 AOD:.4 f: 1.1 AOD:.61 f: 1. AOD:.85 f: 1. AOD:.77 f:.8 AOD: 1.28 f:.8 AOD:.73 f: 1.1 lin AOD: 1.28 f: 1.1 lin AOD:.78 72

73 Comparison of measured DSCDs of NO 2 and HCHO (black dots) to the results of the forward model (coloured lines) damf ratio (or dscd ratio) Reihe1 Measurement Reihe2 S = 1.1 Reihe9 S = 1. Reihe8 S =.8 Reihe3 S =.5 NO Elevation angle [ ] damf ratio (or dscd ratio) Reihe1 Measurement Reihe2 S = 1.1 Reihe9 S = 1. Reihe8 S =.8 Reihe3 S =.5 HCHO Elevation angle [ ] S:.5, L=183m, VCD= molec/cm² S:.8, L=267m, VCD= molec/cm² S: 1., L=32m, VCD= molec/cm² S: 1.1, L=254m, VCD= molec/cm² S:.5, L=282m, VCD= molec/cm² S:.8, L=445m, VCD= molec/cm² S: 1., L=515m, VCD= molec/cm² S: 1.1, L=35m, VCD= molec/cm² 73

74 OD Results for selected days September : 7: 9: 11: 13: 15: 17: south Reihe7 north Reihe6 west Reihe5 AOT_35 AERONET telescopes directed to different azimuth angles NO2 mixing ratio [ppb] : 7: 9: 11: 13: 15: 17: south Reihe2 north Reihe3 west Reihe1 LP-DOAS NO2_[ppb] 6 6 HCHO mixing ratio [ppb] : 7: 9: 11: 13: 15: 17: south north west LP-DOAS Hantzsch Reihe2 Reihe3 #DIV/! HCHO_[ppb] HCHO-PPB Layer height [m] : 7: 9: 11: 13: 15: 17: aerosols south HCHO south NO 2 south north north north west west west 74

75 OD Results for selected days 19 September 23 5: 7: 9: 11: 13: 15: 17: south Reihe7 north Reihe6 west Reihe5 AOT_35 AERONET telescopes directed to different azimuth angles NO2 mixing ratio [ppb] : 7: 9: 11: 13: 15: 17: south Reihe2 north Reihe3 west Reihe1 LP-DOAS NO2_[ppb] 6 6 HCHO mixing ratio [ppb] : 7: 9: 11: 13: 15: 17: south north west LP-DOAS Hantzsch Reihe2 Reihe3 #DIV/! HCHO_[ppb] HCHO-PPB Layer height [m] : 7: 9: 11: 13: 15: 17: aerosols south HCHO south NO 2 south north north north 75 west west west

76 Comparison of trace gas mixing ratios from MAX-DOAS and LP-DOAS (towards north-west) South North West NO 2 NO 2 mixing ratio South 1 5 slope:.76 ±.2 r²: NO 2 mixing ratio LP-DOAS 1 5 slope: 1. ±.3 r²: NO 2 mixing ratio LP-DOAS 1 5 slope: 1.16 ±.3 r²: NO 2 mixing ratio LP-DOAS HCHO HCHO mixing ratio South [ppb] slope: 1.11 r: HCHO mixing ratio LP-DOAS [ppb] slope: 1.16 r: HCHO mixing ratio LP-DOAS [ppb] slope:.98 r: HCHO mixing ratio LP-DOAS [ppb] 76 Wagner et al., AMT 211

77 Examples for MAX-DOAS profile inversion, CINDI campaign, Cabauw, The Netherlands, Summer Aerosol extinction NO2 concentration 77

78 Ceilometer data } Optimal Estimation Cabauw, Paramerised retrievals }Udo Friess, IUP 78 Heidelberg

79 Ceilometer data } } Optimal Estimation Cabauw, Paramerised retrievals Udo Friess, IUP 79 Heidelberg

80 Validation for column data and surface values Comparison of MAX-DOAS AODs at 36, 477, 577, and 63 nm and a co-located sun photometer observations. Better agreement for short wavelengths Clemer et al., ACP 21 8

81 Extinction coefficient retrieved by MAX-DOAS vs. in-situ pm 2.5 measurements Good qualitative agreement Border Air Quality and Meteorology Study (BAQS-Met) at Ridgetown 27 Jamie Halla et al., ACP

82 Extinction coefficient retrieved by MAX-DOAS vs. in-situ measurements. The color code denotes the AOD. Good qualitative agreement, but poor quantitative agreement slope: 3.4 slope: 1.5 Paul Zieger et al., ACP

83 83

84 The whole route of Polarstern on ANT/XX in the year 22/23. The cruise started on and ended on

85 6.E+15 5.E+15 morning NO2 VCD afternoon NO2 VCD NO2 VCD Latitude 4.E+15 3.E+15 2.E+15 1.E+15.E E BrO VCD BrO VCD [molec/cm²] 5. E E E E E E P o la rs te rn B r O V C D A M 2 4 P o la rs te rn B r O V C D P M E E L a titu d e Top: NO 2 VCDs for the Atlantic traverse during May 24 as a function of latitude. Bottom: Latitudinal mean VCDs of BrO in May 25 for SZA between 84 and

86 Enhanced BrO in Antarctica Wagner et al., ACP, 27 86

87 'Bromine explosion' gas phase aerosol, sea ice surface 1Br atom BrO + HO2 -> O2 + HOBr HOBr + H+ + Br - -> Br2 2 Br atoms 2 Br <- hv + Br2 BrO + O 2 <= Br + O 3 87

88 Car MAX-DOAS measurements - determination of emissions - validation of satellite observations Paris Summer 29 (3 measurement days) Paris Winter 21 (2 measurement days) New Dehli 21 & 211 (8 measurement days) Elevation angles: Typical integration time: 3 s R. Shaiganfar, MPIC 88 Mainz

89 Emission estimates for Paris from car MAX-DOAS Car MAX-DOAS Car MAX-DOAS

90 Car MAX-DOAS in Rhein-Main region Frankfurt Mainz, 5th November 215 Sebastian Donner 9

91 Car MAX-DOAS around Mannhein/Ludwigshafen 1:3 12: 11:3 13: 24 August, 29 Ibrahim et al., ACP, 21 91

92 A) Emission estimates from car MAX-DOAS F NO2 S VCD NO2 (s) w n ds Wind vector Normal vector of driving route B) F NO c L c F x NO 2 Correction for NO x to NO 2 ratio Correction for NO x lifetime 92

93 C) Extrapolation of encircled emissions to total emission (New Delhi) NO 2 VCD from car MAX-DOAS Correction factor derived from light distribution measured from sky 3 sec spatial resolutin 93

94 NO x emissions New Delhi Shaiganfar et al., ACP

95 Comparison to Chimere model simulations (Paris) Hervé Pepetin, Matthias Beekmann, LISA, Paris 95

96 Validation of OMI satellite observations Paris, Summer 29 96

97 Paris New Delhi summer winter Over polluted regions satellite observations systematically underestimate the tropospheric NO 2 VCD 97

98 Ma et al., ACP 213 (28 21) (28 211) Comparison of tropospheric NO 2 VCD over Beijing. Satellite data are systematically lower than the MAX-DOAS. Why? Coarse spatial resolution of satellite data Too large AMF used in satellite data analysis (aerosols shield part of the tropospheric NO 2 ) 98

99 Imaging DOAS: 2-dimensional information F. Hoffmann, IUP-Heidelberg 99

100 NO 2 -chimney plume, Power plant Fernheizkraftwerk Heidelberg F. Lohberger, IUP-Heidelberg Lohberger et al., Ground-based imaging differential optical absorption spectroscopy of atmospheric gases, Appl. Optic., 24. 1

101 Imaging DOAS of volcanic emissions SO 2 at Popocatepetl, 15 April, 29 Diploma Thesis, Peter Lübcke, IUP Heidelberg 11

102 Short summary for UV/vis ground based observations: -in general simple retrieval algorithms because thermal emission can be neglected (typically no optimal estimation algorithms are used. -scattered light observations are limited to daylight -from spectral effects (almost) no information on vertical distribution can be derived -several sophisticated techniques exist (e.g. MAX-DOAS) for the retrieval of profile information -instruments at different platforms and with different viewing geometries (and light sources: scattered light and direct light) -typically simple instrumentation 12