Gradient flux measurements at Mace Head

Darius Ceburnis, School of Physics, National University of Ireland Galway, Ireland

Marine submicron aerosol sources, sinks and chemical fluxes

IGAC, Atmospheric Chemistry in the Anthropocene, 17-21 September 2012, Beijing

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Annual average dry SSA mass production flux as computed by several chemical transport andgeneral circulation models range over nearly 2 orders ofmagnitude. de Leeuw et al., 2011Textor et al., 2006.

Large discrepancies exist between different SS parameterisations

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

West coast of Ireland is well positioned to study North Atlantic Ocean with dominant air masses passing over biologically active waters in summer while encountering many storms throughout the year.

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

•Eddy covariance (EC) technique, relaxed eddy accumulation (REA) method, disjunct eddy covariance (DEC) method, all are not really suitable for aerosol chemistry due to required off-line chemical analysis and long sampling time.

•Production or removal processes create concentration gradient in the surface layer.

•Gradient flux method may offer an alternative method to estimate production and/or removal of chemical aerosol species.

How can we measure chemical How can we measure chemical fluxes?fluxes?

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Source

(e.g. ocean surface)

C*C*

production deposition

C*C*

Deposition to

flat/rough surface

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

3m

10m

30m

PM1.0 sampler (Leckel PMX)

Pre-fired quartz filters

Samples were deployed for 7 days, but sampled different number of hours, depending on clean sector conditions

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Eddy covariance

w, Kz

PM1

Gradient samples

Chemical fluxes

Flux-gradient method block Flux-gradient method block diagramdiagram

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

zz dz

dcKF

tK wz 2

2

0

5

10

15

20

25

30

35

0.25 0.3 0.35 0.4 0.45

concentration

height

Fzfc )(

Gradient transport theory or K-theory

Ceburnis et al., 2008 GRL

Concentration gradients can be positive as well as negative

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Un-biased turbulence is a key in determining realistic fluxes

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Primary fluxes – Sea Salt and Sea Spray

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Combined evidence suggests that marine OM is largely insoluble at the origin (sea spray production) only to be removed after being aged (oxidised to become water soluble).

Organic matter fluxes – WIOM vs WSOM

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Data broadly agree with the idea proposed by Gantt et Data broadly agree with the idea proposed by Gantt et al. 2011 that OM enrichment is a combined product of al. 2011 that OM enrichment is a combined product of biological activity and wind speed albeit of unknown biological activity and wind speed albeit of unknown proportions.proportions.

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Comparison of the most recent sea salt parameterisations

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

Acknowledgements

J. Keane-Brennan, J. Ovadnevaite, G. Martucci, C.D. O’Dowd, National University of Ireland Galway

M. Rinaldi, M.C. Facchini, Institute of Atmospheric Sciences and Climate, C.N.R. Bologna

Science Foundation Ireland, EPA Ireland, ESA and SOLAS are acknowledged for funding.

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT

ESA-SOLAS-EGU EO4OcAtm-2014, 28-31 October 2014, Frascati, IT