A new parameterization scheme of the real part of the ambient aerosols refractive index

Abstract

<p><strong>Abstract.</strong> The refractive index of ambient aerosols, which directly determines the aerosol optical properties, is widely used in atmospheric models and remote sensing. Traditionally, the real part of the refractive index (RRI) is mainly parameterized by the measurement of ambient aerosol main inorganic components. In this paper, the characteristics of the ambient aerosol RRI are studied based on the field measurement in the East China. Results show that the ambient aerosol RRI varies significantly between 1.36 and 1.56. The direct aerosol radiative forcing is estimated to vary by 40 % corresponding to the variation of the measured aerosol RRI. We find that the ambient aerosol RRI is highly related with the aerosol effective density (<i>ρ</i><sub>eff</sub>) rather than the main chemical components. However, parameterization schemes of the ambient aerosol RRI by <i>ρ</i><sub>eff</sub> are not available due to the lack of corresponding simultaneous field measurements. For the first time, the size-resolved ambient aerosol RRI and <i>ρ</i><sub>eff</sub> are measured simultaneously by our designed measurement system. A new parameterization scheme of the ambient aerosols RRI using <i>ρ</i><sub>eff</sub> is proposed. The measured and parameterized RRI agree well with the correlation coefficient of 0.76. Knowledge of the ambient aerosol RRI would improve our understanding of the ambient aerosol radiative effects.</p>