Aerosol Properties Computed from Aircraft-Based Observations during the ACE-Asia Campaign: 1. Aerosol Size Distributions Retrieved from Optical Thickness Measurements

Authors

• M. Kuzmanoski, University of New South Wales, Sydney, AustraliaFollow
• M. A. Box, University of New South Wales, Sydney, Australia
• G. P. Box, University of New South Wales, Sydney, Australia
• B. Schmid, Bay Area Environmental Research Institute, Sonoma, California, USA
• J. Wang, Brookhaven National Laboratory, Upton, New York, USA
• P. B. Russell, NASA Ames Research Center, Moffett Field, California, USA
• H. H. Jonsson, Center for Interdisciplinary Remotely-Piloted Aircraft Studies, Marina, California, USA
• J. H. Seinfield, Department of Chemical Engineering, California Institute of Technology, Pasadena, California, USA

Document Type

Article

Date of this Version

2007

Citation

Aerosol Science and Technology, 41:202–216, 2007

Comments

U.S. Government Work

Abstract

In this article, aerosol size distributions retrieved from aerosol layer optical thickness spectra, derived from the 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) measurements during the ACE-Asia campaign, are presented. Focusing on distinct aerosol layers (with different particle characteristics) observed in four vertical profiles, we compare the results of two different retrieval methods: constrained linear inversion and a nonlinear least squares method. While the former does not use any assumption about the analytical form of the size distribution, the latter was used to retrieve parameters of a bimodal lognormal size distribution. Furthermore, comparison of the retrieved size distributions with those measured in-situ, aboard the same aircraft on which the sunphotometer was flown, was carried out. Results of the two retrieval methods showed good agreement in the radius ranges from ~0.1 μm to ~1.2–2.0 μm, close to the range of retrievable size distributions from the AATS-14 measurements. In this radius interval, shapes of retrieved and measured size distributions were similar, in accord with close wavelength dependencies of the corresponding optical thicknesses. Additionally, the effect of a size-resolved refractive index on the retrieved size spectra was investigated in selected cases. Retrieval using a constant refractive index pertaining to particle sizes within the range of retrievable size distributions resulted in a size distribution very close to the one retrieved using a size-resolved refractive index.