Comparison of the aerosol extinction coefficient retrieved
from MAX-DOAS measurements to in-situ measurements
P. Zieger1, K. Clemer2, S. Yilmaz3, R. Fierz-Schmidhauser1, U. Friess3, H. Irie4, B. Henzing5, G. de
Leeuw5,6,7 , J. Mikkila7, T. Wagner8, U. Baltensperger1, and E.Weingartner1
1Paul
Scherrer Institut, 2Belgium Institute for Space Aeronomy, 3University of Heidelberg, 4JAMSTEC, 5TNO,
6Finnish
Meteorological Institute, 7University of Helsinki, 8MPI Mainz
CINDI workshop at BIRA, 10-12 March 2010, Brussels, Belgium
Rel. humidity
Global Atmosphere Watch (GAW)
guideline for aerosol light
scattering measurements:
RH < 30 - 40%
To keep continuous light
scattering measurements
comparable.
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Humidified nephelometer (WetNeph)
Fierz-Schmidhauser et al., 2010 (AMT)
Set-up in the Cabauw tower
Definition:
Scattering enhancement factor
f ( RH ,  ) 
 s ( RH ,  )
 s ( RH  40%,  )
WetNeph
DryNeph
s: scattering coefficient; : wavelength
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Aerosol scattering coefficient
Measurement example (Cabauw)
02 July 09
03 July 09
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
04 July 09
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Aerosol scattering coefficient
Measurement example (Cabauw)
02 July 09
03 July 09
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
04 July 09
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Scattering enhancement factor
Measurement example (Cabauw)
f ( RH ,  ) 
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
 s ( RH ,  )
 s ( RH  40%,  )
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Comparison to MAX-DOAS data
Comparison of ambient in-situ measurements with MAX-DOAS
measurements (lowest height level 0-200m)
Instruments so far:
1.
Belgian Institute for Space Aeronomy (BIRA)
2.
University of Heidelberg (IUPHD)
3.
Japan Agency for Marine-Earth Science and
Technology (JAMSTEC)
4.
Max Planck Institut (MPI)*
*retrieval height varied
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
Ambient aerosol extinction coefficient
 ep  f ( RH amb )  sp   ap
Ambient scattering coefficient

DryNeph, WetNeph (=450,
Absorption coefficient

Photometer (= 660nm)
550, 700nm)

Multi-Angle Absorption
RHamb from tower

 =1.05 (Collaud et al., 2010)
measurements (10-200m)

No change with hygroscopic
growth assumed

Interpolation to MAX-DOAS wavelengths (Ångström law)
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
Golden day 24 June 2009
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
Golden day 24 June 2009
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
Golden day 24 June 2009
Ceilometer 24 June 09
(H. Klein Baltink, KNMI)
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
BIRA: entire campaign
AERONET

BIRA with Cimel retrieval (asymmetry factor and single
scattering albedo as input parameter)

Clouds don’t really influence comparison
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
All instruments
BIRA retrieval repeated
with in-situ measured input
parameters
MPI retrieval height varied
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
All instruments – hour of day
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Comparison to MAX-DOAS data
All instruments – AOD from sun photometer
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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PBL height from ceilometer (H. Klein Baltink, KNMI)
Comparison to MAX-DOAS data
All instruments – PBL height
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Conclusions
-
MAX-DOAS and in-situ measurements agree better than expected
-
Agreement better for low AOD and low PBL cases
-
Retrieval for BIRA improves with ambient in-situ measurements as
input
-
Possible reasons:
-
Stability of boundary layer, influence of upper layers, influence of
homogeneous gradient of aerosol concentration, influence of
clouds (unlikely, checked with AERONET data), …
-
Losses in the inlet system (unlikely), calibration issues (very
unlikely), parameterization of f(RH) (small effect), …
-
Influence of nitrate partitioning ? -> Bas
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Outlook
-
Further analysis, possibly with additional MAX-DOAS instruments
(KNMI and IUPB?), MAX-DOAS: unified assumptions, time grid, etc …
-
Longer time series will bring further insights and might help to prove
or disprove our hypotheses (e.g. IUPHD measured until October)
-
Add Lidar profiles in comparison
-
Paper on in-situ comparison will be submitted by the end of June
2010 together with the profile paper
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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Thank you for your attention!
Thank you for your attention!
… and thank you to all contributors and the CINDI organizers!
Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium
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