Research Questions

• How is the chemical composition* of the aerosol burden in Northern Europe modulated?– What are the chemical properties of the burden during high

pollution events?– What is the vertical distribution of the aerosol chemical

composition?

• What role does chemical composition play in the resultant impacts of the aerosol burden?

• Can we represent the observed spatial distribution using a sophisticated regional model treatment?– Focus upon ammonium nitrate

*Chemical composition = stuff that is measurable with an AMS

A quick advert…

• Examine 41 flights based out of the UK– That’s £1,025,000 just for the

flying! • Represents air masses from

NW Europe and NE Atlantic• Period covers 05/04/05 to

27/09/2006• Focus upon profiles from the

Q-AMS (Quadrupole Aerosol Mass Spectrometer)

• Compare with surface measurements at Harwell

• How does meteorology impact the aerosol burden and its composition?

Vertical Distribution of Sub-micron Aerosol Chemical Composition from North-Western Europe and the North-East Atlantic. Morgan et al., 2009, ACPD submitted.

*SLR: Straight & Level Run

*SLR: Straight & Level Run

Full dataset

Crosses are individual data points (grey are those below the detection limit). Red lines are 25 th, 50th and 75th percentiles for 500m altitude bins. Right panel shows mean and error about the mean.

Atlantic vs Easterley

Atlantic Easterley

Positive Matrix Factorisation (PMF)

Typically Resolved Organic Components:HOA: Hydrocarbon-like Organic AerosolOOA-1: “Aged” Oxygenated Organic Aerosol – characteristic of background/rural mass spectraOOA-2: “Fresher” Oxygenated Organic Aerosol

HOA is analogous to Primary Organic Aerosol (POA).OOA is considered to be representative of Secondary Organic Aerosol (SOA).

HOA versus primary markers

(a) Allan 2004 – Urban Manchester; (b) Kirchstetter et al., 1999 – Tunnel Study (Diesel Trucks); (c) Kirchstetter et al., 1999 – Tunnel Study (Light Duty Vechiles)

Regional scale dominated by OOA

Continental Europe Example

B366 – 8th May 2008Pollution episode dominated by nitrate and OOA-2 (r=0.81)

Complex Vertical Structure

Crosses are mean concentration and bars are standard deviation.Cabauw inlet situated at 60m.

Radiosonde launched from Cabauw at 16:04.

Complex Vertical structure

No PMF information from Cabauw yet

Partitioning is biased towards the particle phase at lower temperature and increased relative humidity

Aging of organic aerosol

Relationship between OOA-2 and nitrate is influenced by OOA-1 organic mass fraction

So what does it all do?

Large increases in mass driven strongly by nitrate – major driver of scattering intensity

What about the indirect effect?

CCN data is not yet finalised but could be interesting…

Comparison of CMAQ-MADRID Predictions & AMS Measurements

Measurements along track of aircraft between 11:30 and 12:30

Paper Plans

1. Aging and partitioning of atmospheric aerosol: Aircraft measurements across Northern Europe

– Evolution of OOA component from fresh to aged– Partitioning of nitrate and organic matter– Focus upon high pressure period during LONGREx– Compare with April and September ADIENT flying

2. Measurement and modelling of ammonium nitrate aerosol in Northern Europe and its resultant impacts

– Spatial gradients during high pressure phase of LONGREx– Broad range of pollution levels during ADIENT– Particular focus upon the vertical distribution in light of

partitioning– Also compare extinction and aerosol optical depth with in-situ

and remote sensing data?