The extinction spectra of laboratory generated sea salt aerosols have been measured from 1μm to 20μm using a Bruker 66v/S FTIR spectrometer. Concomitant measurements include temperature, pressure, relative humidity and the aerosol size distribution. The refractive indices of the sea salt aerosol have been determined using a simple harmonic oscillator band model (Thomas et al., 2004) for aerosol with relative humidities at eight different values between 0.4% to 86%. The resulting refractive index spectra show significant discrepancies when compared to existing sea salt refractive indices calculated using volume mixing rules (Shettle and Fenn, 1979). Specifically, an additional band is found in the refractive indices of dry sea salt aerosol and the new data shows increased values of refractive index at almost all wavelengths. This implies that the volume mixing rules, currently used to calculate the refractive indices of wet sea salt aerosols, are inadequate. Furthermore, the existing data for the real and imaginary parts of the refractive indices of dry sea salt aerosol are found not to display the Kramers-Kronig relationship. This implies that the original data used for the volume mixing calculations is also inaccurate.
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机译：使用Bruker 66v / S FTIR光谱仪测量了1μm至20μm的实验室产生的海盐气溶胶的消光光谱。伴随的测量包括温度，压力，相对湿度和气溶胶尺寸分布。海盐气溶胶的折射率已使用简单的谐波振荡器带模型（Thomas等，2004）确定了气溶胶的相对湿度，其相对湿度在0.4％至86％之间的八个不同值处。与使用体积混合规则计算得出的现有海盐折射率相比，所得的折射率光谱显示出明显的差异（Shettle和Fenn，1979年）。具体而言，在干海盐气溶胶的折射率中发现了一个附加谱带，新数据显示几乎所有波长处的折射率值都增加了。这意味着当前用于计算湿海盐气溶胶的折射率的体积混合规则不充分。此外，发现干海盐气溶胶的折射率的实部和虚部的现有数据均未显示Kramers-Kronig关系。这意味着用于体积混合计算的原始数据也不准确。
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