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 MainzCINDI workshop at BIRA, 10-12 March 2010, Brussels, Belgium

2Paul Zieger, 2nd CINDI workshop, 10-11 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.

3Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Humidified nephelometer (WetNeph)

)%,40(

),(),(

RH

RHRHf

s

s

Definition: Scattering enhancement factor

WetNeph

DryNeph

Fierz-Schmidhauser et al., 2010 (AMT)

sscattering coefficient;wavelength

Set-up in the Cabauw tower

4Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Measurement example (Cabauw)

02 July 09 03 July 09 04 July 09

Aero

sol sc

att

eri

ng c

oeffi

cient

5Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Measurement example (Cabauw)

02 July 09 03 July 09 04 July 09

Aero

sol sc

att

eri

ng c

oeffi

cient

6Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Measurement example (Cabauw)

Sca

tteri

ng e

nhance

ment

fact

or

)%,40(

),(),(

RH

RHRHf

s

s

7Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS data

Comparison of ambient in-situ measurements with MAX-DOAS

measurements (lowest height level 0-200m)

Instruments so far:

*retrieval height varied

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)*

8Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS data

apspambep RHf )(

Ambient aerosol extinction coefficient

Absorption coefficientAmbient scattering coefficient

Multi-Angle Absorption

Photometer (= 660nm)

=1.05 (Collaud et al., 2010)

No change with hygroscopic

growth assumed

DryNeph, WetNeph (=450,

550, 700nm)

RHamb from tower

measurements (10-200m)

Interpolation to MAX-DOAS wavelengths (Ångström law)

9Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataGolden day 24 June 2009

10Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataGolden day 24 June 2009

11Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataGolden day 24 June 2009

Ceilometer 24 June 09

(H. Klein Baltink, KNMI)

12Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataBIRA: entire campaign

BIRA with Cimel retrieval (asymmetry factor and single

scattering albedo as input parameter)

Clouds don’t really influence comparison

AERONET

13Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataAll instruments

MPI retrieval height varied

BIRA retrieval repeated with

in-situ measured input

parameters

14Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataAll instruments – hour of day

15Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataAll instruments – AOD from sun photometer

16Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Comparison to MAX-DOAS dataAll instruments – PBL height

PB

L heig

ht

from

ceilo

mete

r (H

. K

lein

Balt

ink,

KN

MI)

17Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

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

18Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

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

19Paul Zieger, 2nd CINDI workshop, 10-11 March 2010, Brussels, Belgium

Thank you for your attention!

Thank you for your attention!

… and thank you to all contributors and the CINDI organizers!