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FTIR studies of the nucleation and composition properties of terrestrial and Martian clouds.

机译：FTIR研究陆云和火星云的成核和组成特性。

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摘要

For application to the remote sensing of cirrus and polar stratospheric clouds, the optical constants of ice in the near infrared (7000–4000 cm−1) at tropospheric temperatures were calculated from FTIR transmission spectra. At each temperature, a series of ice films ranging from 200 to 1100 μm was condensed. The optical constants were calculated using an iterative Kramers-Kronig program based on the optical design of our chamber.; Secondly, during the 2000 SOLVE Arctic campaign, the composition of polar stratospheric clouds (PSCs) was probed by solar IR extinction, a direct application of laboratory determined optical constants. High resolution FTIR occultation spectra from aboard the DC-8 were analyzed to identify the stratospheric aerosol. Absorption spectra were produced by ratioing spectra recorded on days in which PSCs were present to spectra recorded on clear days, in spectral windows with little or no gas phase absorption. The resulting broad absorption features were fit to spectra calculated from a Mie extinction model using the optical constants of PSC particles of different compositions. Spectra recorded on January 27, 2000 clearly show the absorption features representative of nitric-acid trihydrate (NAT). This is the first direct field confirmation of NAT outside of mountain lee wave-induced PSCs.; Lastly, greenhouse warming due to the infrared scattering by CO 2 clouds may have allowed for liquid water on early Mars and may even be responsible for having maintained the early Earth's surface temperature above freezing. The warming potential of these clouds depends on their particle size, which is determined by the nucleation and growth conditions. I studied the nucleation and growth of CO2 on water ice under Martian atmospheric conditions, and found that a critical saturation, S = 1.34, is required for nucleation, corresponding to a contact parameter between ice and CO2 of m = 0.95. After nucleation occurs, growth of CO2 is rapid and proceeds without a surface kinetic barrier. These results suggest particles larger than those being currently suggested for the present and past Martian atmospheres. Using this information in a microphysical model described in a companion paper, we found that CO 2 clouds are best described as “snow”, having a small number of large particles.
机译：为了应用于卷云和极地平流层云的遥感，根据FTIR透射光谱，计算了对流层温度下近红外（7000-4000 cm -1> ）中冰的光学常数。在每个温度下，冷凝范围从200到1100μm的一系列冰膜。光学常数的计算基于我们室的光学设计，使用了迭代的Kramers-Kronig程序。其次，在2000年的SOLVE Arctic活动中，通过太阳IR消光探测了平流层极地云（PSC）的成分，这是实验室确定的光学常数的直接应用。分析了DC-8上的高分辨率FTIR掩星，以鉴定平流层气溶胶。在几乎没有气相吸收或没有气相吸收的光谱窗口中，通过将存在PSC的各天记录的光谱与无色的各天记录的光谱比值，得出吸收光谱。使用不同组成的PSC粒子的光学常数，将所得的宽吸收特征拟合至根据Mie消光模型计算出的光谱。 2000年1月27日记录的光谱清楚地表明了硝酸三水合物（NAT）的吸收特征。这是首次在山里风诱导的PSC之外直接进行NAT的现场确认。最后，由于CO 2 云的红外散射导致的温室变暖可能在火星早期允许液态水，甚至可能导致地球早期的地表温度保持在冰点以上。这些云的变暖潜力取决于它们的粒径，这取决于成核和生长条件。我研究了火星大气条件下水冰上CO 2 的成核和生长，发现成核需要临界饱和度 S = 1.34，这对应于冰与 m 的CO 2 之间的接触参数= 0.95。成核后，CO 2 的生长迅速，并且没有表面动力学屏障。这些结果表明，与目前和过去的火星大气相比，目前所建议的粒子要大。在随附论文中描述的微物理模型中使用此信息，我们发现CO 2 云最好描述为“雪”，具有少量大颗粒。

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  • 作者

    Glandorf, David Lee.;

  • 作者单位

    University of Colorado at Boulder.;

  • 授予单位 University of Colorado at Boulder.;
  • 学科 Physics Atmospheric Science.; Geophysics.; Chemistry Physical.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 p.5166
  • 总页数 139
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 大气科学（气象学）;
  • 关键词

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