Publication Abstracts

Fridlind and Jacobson 2003

Fridlind, A.M., and M.Z. Jacobson, 2003: Point and column aerosol radiative closure during ACE 1: Effects of particle shape and size. J. Geophys. Res., 108, no. D3, 4094, doi:10.1029/2001JD001553.

We used data collected during the First Aerosol Characterization Experiment (ACE 1) to study point and column aerosol radiative closure over the remote ocean. To test point closure, total and hemispheric backscattering coefficients calculated with a Mie single-scattering model were compared with measurements made by ship and aircraft at three wavelengths (400, 550, and 700 nm). On the ship, assuming spherical particles, calculated total scattering was usually within 10% of measurements (closure obtained in >80% of the cases) but calculated backscattering was usually 15-25% lower than measurements (closure obtained in <50% of the cases). When a model for particle nonsphericity was applied to the dried sea spray, assuming the particles to be ideal cubes or irregular convex and concave crystals resulted in overestimation of backscattering. However, when nonsphericity parameters were fit to the measurements, calculated backscattering was also usually within 10% of measurements (closure obtained in >80% of the cases). On the aircraft, however, calculated scattering and backscattering were usually lower than measurements by 20-45% regardless of assumed particle shape (closure obtained in <50% of the cases), likely owing to differences in the aerosol inlet penetration efficiencies to each instrument or unidentified uncertainties in the measured number size distributions or scattering coefficients. To test column closure, aerosol extinction profiles calculated from in situ observations (below 5.5 km) and satellite observations (above 5.5 km) were vertically integrated, and the resulting aerosol optical depth was compared with measurements made on the ship during two clear-sky days at three wavelengths (500, 778, and 862 nm). Calculated spectral optical depths were usually within 25% of measurements (closure obtained at one or more wavelengths on both days), and agreement at longer wavelengths was improved when satellite measurements were spectrally scaled using in situ model results. On both days, large sea salt particles produced a spectrally neutral aerosol optical depth in the marine boundary layer whereas smaller ammonium sulfate particles contributed to greater optical depth at shorter wavelengths in the overlying upper atmosphere.

Export citation: [ BibTeX ] [ RIS ]

BibTeX Citation

@article{fr08000d,
  author={Fridlind, A. M. and Jacobson, M. Z.},
  title={Point and column aerosol radiative closure during ACE 1: Effects of particle shape and size},
  year={2003},
  journal={J. Geophys. Res.},
  volume={108},
  number={D3},
  pages={4094},
  doi={10.1029/2001JD001553},
}

[ Close ]

RIS Citation

TY  - JOUR
ID  - fr08000d
AU  - Fridlind, A. M.
AU  - Jacobson, M. Z.
PY  - 2003
TI  - Point and column aerosol radiative closure during ACE 1: Effects of particle shape and size
JA  - J. Geophys. Res.
VL  - 108
IS  - D3
SP  - 4094
DO  - 10.1029/2001JD001553
ER  -

[ Close ]

• Return to 2003 Publications

• Return to Publications Homepage