Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 2495-2508, 2017
https://doi.org/10.5194/acp-17-2495-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
17 Feb 2017
Aerosol scattering effects on water vapor retrievals over the Los Angeles Basin
Zhao-Cheng Zeng1,2, Qiong Zhang1, Vijay Natraj3, Jack S. Margolis4,*, Run-Lie Shia1, Sally Newman1, Dejian Fu3, Thomas J. Pongetti3, Kam W. Wong1,3, Stanley P. Sander3, Paul O. Wennberg1, and Yuk L. Yung1 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
2Institute of Space and Earth Information Science, The Chinese University of Hong Kong, Hong Kong, China
3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
41842 Rose Villa St., Pasadena, CA 91107, USA
*retired
Abstract. In this study, we propose a novel approach to describe the scattering effects of atmospheric aerosols in a complex urban environment using water vapor (H2O) slant column measurements in the near infrared. This approach is demonstrated using measurements from the California Laboratory for Atmospheric Remote Sensing Fourier Transform Spectrometer on the top of Mt. Wilson, California, and a two-stream-exact single scattering (2S-ESS) radiative transfer (RT) model. From the spectral measurements, we retrieve H2O slant column density (SCD) using 15 different absorption bands between 4000 and 8000 cm−1. Due to the wavelength dependence of aerosol scattering, large variations in H2O SCD retrievals are observed as a function of wavelength. Moreover, the variations are found to be correlated with aerosol optical depths (AODs) measured at the AERONET-Caltech station. Simulation results from the RT model reproduce this correlation and show that the aerosol scattering effect is the primary contributor to the variations in the wavelength dependence of the H2O SCD retrievals. A significant linear correlation is also found between variations in H2O SCD retrievals from different bands and corresponding AOD data; this correlation is associated with the asymmetry parameter, which is a first-order measure of the aerosol scattering phase function. The evidence from both measurements and simulations suggests that wavelength-dependent aerosol scattering effects can be derived using H2O retrievals from multiple bands. This understanding of aerosol scattering effects on H2O retrievals suggests a promising way to quantify the effect of aerosol scattering on greenhouse gas retrievals and could potentially contribute towards reducing biases in greenhouse gas retrievals from space.

Citation: Zeng, Z.-C., Zhang, Q., Natraj, V., Margolis, J. S., Shia, R.-L., Newman, S., Fu, D., Pongetti, T. J., Wong, K. W., Sander, S. P., Wennberg, P. O., and Yung, Y. L.: Aerosol scattering effects on water vapor retrievals over the Los Angeles Basin, Atmos. Chem. Phys., 17, 2495-2508, https://doi.org/10.5194/acp-17-2495-2017, 2017.
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Short summary
We propose a novel approach to describing the scattering effects of atmospheric aerosols using H2O retrievals in the near infrared. We found that the aerosol scattering effect is the primary contributor to the variations in the wavelength dependence of the H2O SCD retrievals and the scattering effects can be derived using H2O retrievals from multiple bands. This proposed method could potentially contribute towards reducing biases in greenhouse gas retrievals from space.
We propose a novel approach to describing the scattering effects of atmospheric aerosols using...
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