MAX-DOAS observations of NO 2 in NDACC: status and perspectives

Transcription

1 MAX-DOAS observations of NO 2 in NDACC: status and perspectives F. Hendrick 31/01/2015 C. Gielen, G. Pinardi, B. Langerock, M. De Mazière, and M. Van Roozendael Royal Belgian Institute for Space Aeronomy(BIRA-IASB) + NDACC UV-vis Working Group 1

2 Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) Measures the absorption of sunlight scattered by molecules and aerosols in the UV-visible range Off-axis viewing directions + zenith: Typical elevationangles: 0, 1, 2, 3, 6, 8, 10, 12, 15, 30, and 90 Measurements from ~85 SZA sunrise to 85 SZA sunset ~20 minutes per scan sza θ 31/01/2015 Scattering Stratosphere * Troposphere Spectrometer Ground * GAW N-cycle Workshop, University of York, UK, 13 April φ φ = 10 φ = 6 φ = 3 elevation 2

3 MAX-DOAS System Optical head including telescope on a suntracker Two grating spectrometers (UV + visible) Controlling and acquisition unit GAW N-cycle Workshop, University of York, UK, 13 April

4 MAX-DOAS retrieval Two-step method: 1. Spectral inversion giving the slant column densities (SCDs): ' I( λ) ' τ ( λ) = ln = σ ( λ). SCD( λ) ' I0( λ) 2. Vertical column and/or profile retrieval from SCDs: VCD ( θ, α, ϕ) = SCD( θ, α, ϕ) AMF( θ, α, ϕ) GAW N-cycle Workshop, University of York, UK, 13 April

5 MAX-DOAS horizontal representativeness 360 nm 450 nm 560 nm MAD-CAT intercomparison campaign (June-July 2013; MPIC/Mainz) Mainz (MPIC), 17 June 2013 Ortega et al., AMT, 2015 MAX-DOAS and satellite nadir air quality measurements are sensitive to similar spatial domain (e.g.,omi and TROPOMI pixel sizes: 13x24and 3.5x7km 2,respectively) MAX-DOAS suitable for satellite nadir air quality instrument validation

6 NDACC-related MAXDOAS stations (Network for the Detection of Atmospheric Composition Change) International research network of ~90 remote sensing stations (Dobson/Brewer, FTIR, LIDAR, MW, sondes, UV-vis) Contributor to the GAW programme Main objective: Observing and understanding the physical/chemical state of the stratosphere and troposphere Plays a key role for trend studies, ground truthing of satellite data, model assessment MAX-DOAS systemsand algorithms are still under development, generallyoperated at scientific levelby expert scientists GAW N-cycle Workshop, University of York, UK, 13 April Harmonisation efforts under progress(started in 2011 with the FP7 project NORS)

7 Model validation: CAMS C-IFS (global) OHP (Southern France) Rural 27/01/2015 Xianghe(Beijing suburban area) suburban/ Highly polluted 31/01/2015 Uccle (Brussels) Urban/ Polluted 7

8 Model validation: CAMS Regional Model Ensemble (LOTOS-EUROS, CHIMERE, EMEP, EMEP-MACCEVA, SILAM, MOCAGE) Bremen (Germany)-2011 Urban Uccle (Brussels)-2012 OHP (Southern France)-2010 Urban Rural Correlation plots 27/01/2015 Seasonal variation Bremen (Germany) Uccle (Brussels) OHP (Southern France) 31/01/2015 Vertical profiles Bremen (Germany) Uccle (Brussels) OHP (Southern France) Courtesy A. Blechschmidt(IUP- Bremen) + CAMS regional model team + IUP-Bremen and BIRA-IASB MAX-DOAS teams 8

9 Satellite NO 2 validation using MAX-DOAS About 20 MAX-DOAS stations have been used to validate tropospheric NO 2 from nadir satellite sensors(omi/aura, GOME-2/METOP-A): SATELLITE MAXDOAS VCD tropo = (SCD total AMF strato VCD strato )/AMF tropo Pixels (cloud fraction<20%) falling within 50km around the stations, MAX-DOAS interpolated at the satellite overpass time GAW N-cycle Workshop, University of York, UK, 13 April

10 OMI (TEMIS) versus MAX-DOAS Overpass time: 13h30 Suburbanand Remote Urban sites Validation results strongly depend on the location of the station, with generally smaller satellite columns than the ground-based MAX-DOAS. - Good agreement in suburban and remote stations - Urbanconditions: MAX-DOAS is generally higher than satellite impact of local pollution sources, not adequately sampled at the coarse resolution of the pixel 10

11 MAX-DOAS versus in-situ at Uccle (Brussels) 25/07/ B km 41R012 + MAX-DOAS 17/07/

12 MAX-DOAS versus in-situ at Hohenpeissenberg Courtesy R. Holla(DWD) 12

13 Linking MAX-DOAS NO 2 measurements to the in-situ standards: ISSJ study case Linking MAX-DOAS and in-situ through the use of FLEXPART backward trajectory model simulations: Selection of comparison pairs having similar air mass history Generation of high-resolution vertical profiles which can be adjusted to the insitu surface concentration / km asl altitude range S. Henne(EMPA) in FP7 projectsactris and NORS 13

14 Nitrous acid (HONO) from MAX-DOAS CAS/IAP (06/ /2009) H O N O NO 2 Hendrick et al., ACP, 2014 (03/2010 till now) A O D 14

15 Nitrous acid (HONO) from MAX-DOAS Hendrick et al., ACP,

16 MAX-DOAS harmonisation: FP7 project NORS ( ) Perform the required research and developments to optimize the NDACC data products for the purpose of supporting the quality assessments of CAMS MAX-DOAS data harmonisation (NO 2, HCHO, aerosols): retrievalalgorithmsand settings, uncertainties, spatial representativeness, cloud flagging, data reporting(geoms hdf format), etc NRT (24h latency) data submission to the RD database: ftp://ftp.cpc.ncep.noaa.gov/ndacc/rd/ NORS validation server: 16

17 Perspectives: Centralised Processing System ( ) Stations:Ny-Alesund, Bremen, Cabauw, Uccle, Mainz, Heidelberg, Xianghe, Athens, Bujumbura, Lauder, Neumayer 17

18 Final remarks MAX-DOAS instruments are currently monitoring tropospheric NO 2 yearround at ~50 sites worldwide (urban, suburban, and remote conditions) HONO can bemeasured forhigh NO x andaerosolsemissions MAX-DOAS provides vertical column + information on the vertical distribution (especially the surface concentration) Suitable correlative data for satellite nadir air quality instrument validation Could be used as a link between in-situ air quality networks and satellite data Harmonisation efforts currently under progress (FP7 projects NORS, QA4ECV,ESA project FRM 4 DOAS,CINDI-IIcampaign) Updated NDACC data policy We are currently aiming at integrating (MAX)DOAS in ACTRIS RI. 18

19 Updated NDACC data policy Access to the NDACC data has been and will be further improved by: Rapid delivery (latency: 1 month or less) database in addition to the consolidated database Since 2016, consolidated data must be publicly accessible at latest 1 year after data acquisition (instead of 2 years) Renewed NDACC website with more direct access and visualisation of the data (hopefully by end 2016) NDACC Interjournal(ACP, AMT, ESSD) Special Issue in 2016, for the 25th anniversary of NDACC 19

20 Final remarks MAX-DOAS instruments are currently monitoring tropospheric NO 2 yearround at ~50 sites worldwide (urban, suburban, and remote conditions) HONO can bemeasured at high NO x and aerosolsemissions MAX-DOAS provides vertical column + information on the vertical distribution (especially the surface concentration) Suitable correlative data for satellite nadir air quality instrument validation Could be used as a link between in-situ air quality networks and satellite data Harmonisation efforts currently under progress (FP7 projects NORS, QA4ECV,ESA project FRM 4 DOAS,CINDI-IIcampaign) Updated NDACC data policy We are currently aiming at integrating (MAX)DOAS in ACTRIS RI. 20

21 Back-up slides 21

22 DOAS fit NO 2 in Beijing Ma et al., ACP,

23 MAX-DOAS data format homogeneisation Clear-sky, thinclouds, thick clouds, broken clouds 4 GEOMS templates(off-axis trace gas + aerosols, zenith, and directsun; see AVDC at 23

24 GOME-2A (DLR GDP4.8) versus MAX-DOAS Overpass time: 9h30 Suburbanand Remote Urban sites Validation results strongly depend on the location of the station, with generally smaller satellite columns than the ground-based MAX-DOAS. - Good agreement in suburban and remote stations - Urbanconditions: MAX-DOAS is generally higher than satellite impact of local pollution sources, not adequately sampled at the coarse resolution of the pixel 24