Transcript ADIENT_Meeting_April_2009

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…
Vertical Distribution of Sub-micron Aerosol Chemical Composition from
North-Western Europe and the North-East Atlantic.
Morgan et al., 2009, ACPD submitted.
• 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?
*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 25th, 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
Aerosol
OOA-1: “Aged” Oxygenated Organic
Aerosol – characteristic of
background/rural mass spectra
OOA-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 2008
Pollution 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
Partitioning is biased towards the particle phase at lower temperature and
increased relative humidity
No PMF information from Cabauw yet
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?