Water vapour foreign-continuum absorption in near-infrared windows from laboratory measurements.
Water vapour foreign-continuum absorption in near-infrared windows from laboratory measurements.
复制标题
实验室测量的近红外窗中的水蒸气外来连续吸收。
DOI：
10.1098/rsta.2011.0218
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Ptashnik IV
中科院分区：
文献类型：
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作者：
Ptashnik IV
长期以来，人们一直认为，在相对高红外透过率的波长区域（所谓的“窗口”）内，大气对辐射的吸收主要是水蒸气的自连续体，即由H2O−H2O对相互作用引起的光谱平滑吸收。由于外来连续体的吸收（即主要由地球大气中的H2O−n2双分子吸收引起）在窗口中被认为是可以忽略不计的。我们报告了在温度为350和430 K之间的四个近红外窗口（1.1和5 μm (9000-2000 cm−1)）中，从高分辨率实验室测量中获得的水蒸气外来连续体的新检索。我们的结果表明，这些窗口中的外来连续体对温度的依赖性非常弱，通常比目前许多气候和天气预报模式中使用的连续体的表示要强一到两个数量级。这表明在所研究的窗口中，由于外来连续统引起的吸收可以与大气条件下的自连续统相媲美。与广泛使用的MTCKD （mlawer - to宾- clough - kneizys - davies）外来连续体模式相比，使用这些新测量值计算出的全球平均晴空大气太阳辐射吸收量增加了约0.46 W m - 2（或晴空总吸收量的0.6%）。
For a long time, it has been believed that atmospheric absorption of radiation within wavelength regions of relatively high infrared transmittance (so-called ‘windows’) was dominated by the water vapour self-continuum, that is, spectrally smooth absorption caused by H2O−H2O pair interaction. Absorption due to the foreign continuum (i.e. caused mostly by H2O−N2bimolecular absorption in the Earth's atmosphere) was considered to be negligible in the windows. We report new retrievals of the water vapour foreign continuum from high-resolution laboratory measurements at temperatures between 350 and 430 K in four near-infrared windows between 1.1 and 5 μm (9000–2000 cm−1). Our results indicate that the foreign continuum in these windows has a very weak temperature dependence and is typically between one and two orders of magnitude stronger than that given in representations of the continuum currently used in many climate and weather prediction models. This indicates that absorption owing to the foreign continuum may be comparable to the self-continuum under atmospheric conditions in the investigated windows. The calculated global-average clear-sky atmospheric absorption of solar radiation is increased by approximately 0.46 W m−2(or 0.6% of the total clear-sky absorption) by using these new measurements when compared with calculations applying the widely used MTCKD (Mlawer–Tobin–Clough–Kneizys–Davies) foreign-continuum model.