Observations of a distinctive infra‐red spectral feature in the atmospheric spectra of polar stratospheric clouds measured by the CRISTA instrument
Observations of a distinctive infra‐red spectral feature in the atmospheric spectra of polar stratospheric clouds measured by the CRISTA instrument
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DOI：
10.1029/2003gl017231
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发表时间：
2003-08
影响因子：
5.2
通讯作者：
R. Spang;J. Remedios
中科院分区：
文献类型：
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作者：
R. Spang;J. Remedios
在寒冷的极地冬季，极地平流层云粒子（PSC）会强烈影响平流层下部的红外发射光谱。1997年8月，CRISTA实验观测到许多南极PSC，利用临边探测光谱对这些红外特征进行了研究。在这些光谱中，许多光谱都发现了一个以820 cm−1为中心的独特光谱特征，这是第一次在大气中的PSC光谱中观察到一个特定的波段。这一特征可以归因于NO3−离子的ν2带，并强烈表明颗粒中有凝聚的硝酸组分，其形式为固体硝酸三水合物（NAT）或液体三元溶液（STS）。光谱特征属于CRISTA记录的PSC观测的确定子集。粒子在远高于192 K的温度下观察到，允许温度误差，并且建议NAT粒子是光谱特征的最可能来源。此外，它表明，PSC事件，其中没有光谱特征是目前只观察到低于192 K，并显示出非常相似的HNO 3-温度关系的STS粒子。
Polar stratospheric cloud particles (PSCs) are known to strongly influence the infra‐red emission spectrum of the lower stratosphere in cold polar winters. The characteristics of these infra‐red features have been examined using limb sounding spectra recorded by the CRISTA experiment in August 1997 when many Antarctic PSCs were observed. A distinctive spectral feature centered at 820 cm−1 has been identified in many of these spectra, the first time that a particular band has been observed in the spectra of PSCs in the atmosphere. The feature can be attributed to the ν2 band of the NO3− ion and strongly suggests a condensed nitric acid component to the particles in the form of solid nitric acid trihydrate (NAT) or liquid ternary solution (STS). The spectral signatures belong to a definite sub‐set of the PSC observations recorded by CRISTA. The particles are observed at temperatures well above 192 K, allowing for temperature errors, and it is suggested that NAT particles are the most likely source of the spectral signature. In addition, it is shown that PSC events in which no spectral signature is present are only observed below 192 K and display a very similar HNO3‐temperature relationship to STS particles.