Time Variability of Chemical Species in Mt. Lemmon Aerosol using Principal Component Analysis

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Time Variability of Chemical Species in Mt.
LemmonAerosol using Principal Component Analysis

• Anna Wonaschütz
• ATMO 529 Class Project
• Dec. 3rd, 2007

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Description of the Data (I)?

• Matichuk et al., 2006
• mass concentration (monthly averages) of
• 8 chemical species in aerosols
• 4 aerosol precursor gases
• PM2.0
• time range Sept. 1992 - Apr. 2003
• location Mt. Lemmon, AZ

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Location

• Mt. Lemmon, elevation 2791 m/9157 ft
• winter (NDJF) summit in free troposphere
  (clean, continental air masses)?
• summer(MJJA) summit in planetary boundary
  layer
• fall (SO) and spring (MA) boundary layer depth
  varies
• Shaw, 2007, Philippin Betterton, 1997

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Location

• Mt. Lemmon, elevation 2791 m/9157 ft
• winter (NDJF) summit in free troposphere
  (clean, continental air masses)?
• summer(MJJA) summit in planetary boundary
  layer
• fall (SO) and spring (MA) boundary layer depth
  varies
• Shaw, 2007, Philippin Betterton, 1997

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Description of the Data (II)?

• Aerosol (PM2.0)
• sulfate (SO42-), nitrate (NO3-), chloride (Cl-),
  sodium (Na), ammonium (NH4), calcium (Ca2),
  elemental carbon (EC), organic carbon (OC)?
• precursor gases
• ammonia (NH3), nitric acid (HNO3), sulfuric acid
  (H2SO4, proxy for SO2), hydrochloric acid (HCl)?

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Description of the Data (III)?

• Summary of results from Matichuk et al., 2006
• 1. all species show a strong seasonal dependence
• 2. trends - OC, Cl- and Na insignificant
• - NH3, SO42-, NH4, SO2 negative
• - all other species positive

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Analysis Method

• PCA using SVD
• U...principal components (derived variables)?
• S...singular values (square root of eigenvalues)?
• V...EOF's (eigenvectors of the correlation
  matrix)?
• 1st PC timeseries that represents most of the
  variability of the original dataset, i.e. the
  timeseries of the chemical species
• EOF's contribution of the PC to each species

data USV
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Data Preparation

• units
• mg/m3 (aerosol), ppbv (gases) standardize
• gaps
• gap in one chemical species eliminate those
  months for all other species

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• 53 variance explained

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• 15.5 variance explained

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References

• Matichuk R., Barbaris B., Betterton E., Hori M.,
  Murao N., Ohta S., Ward D. A Decade of Aerosol
  and Gas Precursor Chemical Characterization at
  Mt. Lemmon, Arizona (1992 to 2002), Journal of
  the Meteorological Society of Japan, Vol. 84,
  No.4, 2006
• Philippin S., Betterton E.A. Cloud Condensation
  Nuclei Concentrations in Southern Arizona
  Instrumentation and Early Observations,
  Atmospheric Research 43 (3), 1997
• J.H. Seinfeld S.N. Pandis Atmospheric
  Chemistry and Physics, 2nd edition, 2006, John
  Wiley Sons, Inc.
• Shaw G. Aerosols at a mountaintop observatory
  in Arizona, Journal of Geophysical Research,
  Vol. 112, 2007
• D.S. Wilks Statistical Methods in the
  Atmospheric Sciences, 2nd edition, 2006, Elsevier