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Wir schaffen Wissen – heute für morgen
27.08.2014
Paul Scherrer Institute
PMF runs with SoFi based on ME-2
F. Canonaco, K. Dällenbach, I. El Haddad, M. Crippa , C.
Bozzetti, J. Slowik, A. Prevot, U. Baltensperger, …
Motivation – Organic Source apportionment
page 2F. Canonaco, PSI Switzerland
ACSM measures mainly
ammonium nitrate,
ammonium sulfate,
ammonium chloride and
Organic mixture � Source apportionment technique
Source apportionment technique - PMF
page 3F. Canonaco, PSI Switzerland
X
{n x m}=
G
{n x p}
F
{p x m}
species j: 1…m
columns„factor time series“
factors
+E
{n x m}
k: 1…p
sam
ple
s in
tim
e i
: 1
…n
elelmeasured EXX modmodˆ +=
rows „factor
profiles“
Bilinear model – Positive Matrix Factorization (PMF)
� The rows of the matrix F represent the factor profiles
� The columns of the matrix G represent the factor time series
.
Paatero and Tapper 1994
Method - PMF
page 4F. Canonaco, PSI Switzerland
Least-squares algorithm
Advantages
� Values in G & F are non-negative
� Factors represent sources (POA) / aging (SOA)
Disadvantages
� Assess number of factors
� Constant factor profiles (mass spectra)
� Uncertainties are not well-known, minimal Q-value is not necessarily the best solution
� Investigate the solution space even for slightly higher Q-values (few %)
� PMF solutions suffer from rotational ambiguity
� Investigate the solution space
∑∑= =
=
m
i
n
1jij
ije
Q1
2
σeij: difference (measured – model)
σij: uncertainty (measurement)
������ = � · = � · � · �� · = �′ · ′
Paatero 1999, Paatero and Hopke 2008
Source apportionment technique – PMF/ME2 solver
page 5F. Canonaco, PSI Switzerland
PMF2 solver ME2 solver
global rotational tool (fpeak) global rotational tool (fpeak)
- Individual rotational tool (fpeak)
pull towards zero (G and/or F) Constraining values (G and/or F) a-value/pulling
jp,jp,solutionj,p, faff ⋅±=
a-value approach for F
Paatero 1999, Paatero and Hopke 2008
SoFi – The interface in Igor
page 6F. Canonaco, PSI Switzerland
Canonaco et al., 2013
SoFi – The actual version 4.8
page 7F. Canonaco, PSI Switzerland
Regular features
� Various results plots / residual plots
� Comparison with external tracers
� Validate a PMF solution
Special features
� …
Canonaco et al., 2013
SoFi – correalation plots
page 8F. Canonaco, PSI Switzerland
� Monitor the correlation of a factor time series with external data, e.g. HOA with BC over
different model runs
SoFi – overview plots
page 9F. Canonaco, PSI Switzerland
� Compare different model runs together
SoFi – HR variable plot
page 10F. Canonaco, PSI Switzerland
� HR data, families grouped into UMR
SoFi – reweight panel
page 11F. Canonaco, PSI Switzerland
� Reweight based on averaged S/N ratio
� Reweight based on t-dependent S/N ratio (available with new release)
SoFi – combined PMF (C-value)
page 12F. Canonaco, PSI Switzerland
� C-value approach for combined PMF data, e.g. AMS and gas-phase
SoFi – combined PMF (C-value)
page 13F. Canonaco, PSI Switzerland
� C-value approach
SoFi – The future version
page 14F. Canonaco, PSI Switzerland
Next release
� Fast bilinear ME-2 lane in ME-2 (Paatero)
� Restructuration of SoFi (interface and storage)
� Controlled investigation of the solution space (POA and SOA profiles)
� Propagation of the statistical uncertainty to the PMF results
� Version 4.9 will cover all this…
Canonaco et al., 2013
ME2 interface - Strategy
page 15F. Canonaco, PSI Switzerland
� Constant factor profile for OOA / BBOA is problematic for long-term data
� Run PMF over groups of data, seasons, months, weeks
Source apportionment strategy for long-term data
� Grouped data based on daily temperature in ascending order
� Run PMF over a small window, e.g. one month (Automatic - Au)
� HOA, COA, BBOA were always expected, constrain with the a-value
� model 1-2 OOA factors based on mainly f44/f43 ratio
� optimize solution based on correlation over time and diurnal cycle for:
HOA with NOX / BCtr, BBOA with BCbb, SV-OOA with nitrate /
temperature, LV-OOA with sulfate, cooking lunch peak presence
� Shift PMF frame by a day and rerun PMF (Rolling - Ro)
AuRo – SoFi
� Same sources supposed
� Rolling window allows to dynamically adapt to changing SOA
� Small shift compared to PMF frame allows for a partial propagation of the uncertainty
ME2 interface – AuRo-SoFi result
page 16F. Canonaco, PSI Switzerland
ME2 interface – AuRo-SoFi result
page 17F. Canonaco, PSI Switzerland
ME2 interface – AuRo-SoFi result
page 18F. Canonaco, PSI Switzerland
� Talk at the IAC on the 2nd of September
