The combined ICAD/CAPS NO2 in-situ data set for CINDI II
The combined ICAD/CAPS NO2 in-situ dataset for CINDI2
Johannes Lampel, Alexis Merlaud, Arnoud Frumau, Stefan Schmitt, Denis Pöhler, Martin Horbanski,
Lukas Tirpitz
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
„In-situ“ measurements during CINDI II
„In-situ“ datasets for the CINDI-II period:
ICAD (CE-DOAS) 438-464nm
Instrument Contact Location, height
3 CLD NOx A. Frumau (ECN) Tower, 27, 60, 120, 200m
1 CAPS A. Merlaud (BIRA) Tower, 27m, 200m
1 ICAD (CE-DOAS) J. Lampel (IUP) Tower, 27m
1 LP-DOAS S. Schmitt (IUP) To Tower
CAPS 440±10 nm
[Kebabian et al 2008]
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Available NO2-‘in situ‘ data
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
CAPS vs ICAD @ 27m during CINDI II
Good correlation between the ICAD and CAPS instruments, but a scaling factor of 1.4!
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Overview Instruments (Intercomparison after CINDI2)
Instrument Time resolution [s] Measured Species
HORIBA APNA 370 60 NO2, NOX, NO
HORIBA APOA 360 60 Ozone
ICADNO2 3 NO2, Glyoxal, H2O
ICADNOX 5 (effective 127) NO2, NOX, Glyoxal, H2O (NOx uncalibrated)
CAPS AS32M 60 NO2
Sources [ppb] Typ. Concentration NO2
[ppb] Typ. Concentration NO [ppb]
Ambient atmosphere 0 - 40 0 - 40
Permeation source 80.5 ± 0.5 < 1
Zero Air Cartridge < 0.2 < 0.2
Candle, Generator More than 1000 More than 1000
NO bottle 0 - 400 0 - 500
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
NO2 Intercomparison
ICADNOX - APNA
ICADNO2 - CAPS calibration source 81ppb
Why chose the ICAD instrument as reference? •Smallest zero drift over time •CAPS scaling factor variable over time? •Unknown interference by CAPS during chambre measurements. •CINDI II NOx monitors differ by 40%
Instrument Slope Offset [ppb] Drift [ppt/d]
APNA 370 1.02 0.36 5
ICADNO2 0.993 -0.007 0.5
CAPS AS32M 1.24 0.2 40-115
Results from intercomparison vs 2nd ICAD:
First two columns: CAPS: drift corrected from zero measurements Ambient air and permeation source measurements (no ‚special‘ measurements)
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
CAPS vs ICAD @ 27m during CINDI II
Good correlation between the 2 instruments, but scaling factor of ~1.4!
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Merging the two datasets (CINDI II)
1. Daily correlation of NO2 in-situ mixing ratios
2. Correcting CAPS Data: Application of fit results (slope, offset)
3. Gaps in ICAD data are filled with rescaled CAPS data
4. Last period where only CAPS data is available is rescaled with the latest correlation results, offset is set to zero!
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Merging the dataset – daily correlations
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Merged data – example
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Merged data - Overview
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Conclusions
• Combined dataset from ICAD and CAPS is found on the data server:
share/ICAD-DOAS/ICAD CAPS merged dataset/
# Column 1: Date and Time in UTC # Column 2: ICAD NO2 VMR [ppb] # Column 3: ICAD NO2 VMR measurement error [ppb] # Column 4: Raw CAPS data [ppb] (interpolated for ICAD lines) # Column 5: Rescaled CAPS data according to daily fit to ICAD data [ppb] # Column 6: Merged NO2 data [ppb] # Column 7: Data source: 1: ICAD; 2: CAPS (rescaled) # Column 8: Data flags # Column 9: NO2 factor (CAPS relative to ICAD) [] # Column 10: NO2 offset (CAPS relative to ICAD) [ppb]
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Conclusions
• Combined dataset from ICAD and CAPS is found on the data server:
share/ICAD-DOAS/ICAD CAPS merged dataset/
• Alexis M. rescaled the 200m CAPS data accordingly
• Scaling in comparison to other data:
– LP-DOAS 1.08 ± 9% (at 27m, interpolated)
– NOx monitor 1 0.87 ± 5% (at 27m)
– NOx monitor 2 0.97 ± 5% (at 27m)
– NOx monitor 3 1.20 ± 10% (at 27m)
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
• Thank you for your attention
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Comparison of CLD NOx Monitors
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
NO2 / NOx from NO titration Experiment
ppb
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Zero-Air Measurements
Instrument Species Mean [ppb]
Std [ppb] Drift [ppt / d] Time resolution [s]
APNA 370 NO2 0.0785 0.28 5 60
NO -1.0801 0.32 -4 60
NOx -1.0052 0.35 1 60
ICADNO2 NO2 -0.0045 0.08 0.5 3
ICADNOX NO2 -0.0520 0.034 -0.1 127
NOx -0.046 0.10 0.2 127
CAPS AS32M NO2 (0.1) 40-115 60
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
• Todo:
– Scaling to other Nox monitors in numbers
– Title page: Logos for ECN and BIRA
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Zero-Air Measurements
Shifted for plotting by - 3 ppb
- 3.5 ppb - 4 ppb
1 minute
1 minute
2 minutes
3 seconds
real offset after two months
CINDI II: - CAPS zero air measurements: every 3h - ICAD zero air measurements show zero drift of less than 0.2ppb / week
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
CAPS O3 Interference (or other effects)
[ppb]
Ozone
CAPS NO2
ICAD NO2
0
100
Titration experiment: NO from bottle and Ozone
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Merged data - Overview
The combined ICAD/CAPS NO2 in-situ data set for CINDI II
Intercomparison results
Instrument Species Slope Offset [ppb]
R2 n
APNA 370 NO2 1.02 0.36 0.990 24800
NO 1.09 -0.623 0.943 18942
NOx 1.07 -0.70 0.989 18372
ICADNO2 NO2 0.993 -0.007 0.998 10513
CAPS AS32M NO2 1.24 0.2 0.988 12900
CAPS: drift corrected from zero measurements Ambient air and permeation source measurements (no ‚special‘ measurements)
