Assessment of the consistency of near‐infrared water vapor line intensities using high‐spectral‐resolution ground‐based Fourier transform measurements of solar radiation
Assessment of the consistency of near‐infrared water vapor line intensities using high‐spectral‐resolution ground‐based Fourier transform measurements of solar radiation
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使用太阳辐射的高光谱分辨率地面傅立叶变换测量来评估近红外水汽线强度的一致性
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发表时间：
2006
期刊：
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通讯作者：
H. Pegrum
中科院分区：
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作者：
S. Casanova;K. Shine;T. Gardiner;M. Coleman;H. Pegrum
[1]大气气体，特别是水蒸气对太阳辐射的吸收的计算取决于谱线参数数据库的质量。近年来，对HITRAN等数据库的审查越来越多，但这主要是在逐个频段的基础上进行的。我们报告了九个高光谱分辨率(0.03厘米−1)测量到达英格兰南部表面的太阳辐射，波数范围为2000到12,500厘米−1(0.8到5μm)，这使得对整个光谱区域的谱线数据库的一致性进行了独特的评估。数据是根据模拟的水汽柱进行评估的，这是使计算和观测一致所必需的；对于一个完全一致的数据库，该水蒸汽柱应随频率恒定。对于HITRAN01数据库，水汽柱中的扩散约为11%，不同光谱区域之间存在明显的移位。HITRAN04数据库在完全更新的3,000至8,000厘米−1光谱区域内的一致性明显更好(约5%分布)，但各个光谱区域之间的不一致仍然存在：例如，在8,000至9,500厘米−1光谱区域，结果表明相对于3,000至8,000厘米−1区域，线强度被低估了18%(±1%)。这些测量还表明了2500至2900厘米−1范围内水蒸气的同位素分馏的影响，其中HDO线主导于H2O中最丰富的同位素的线。
[1] Calculations of the absorption of solar radiation by atmospheric gases, and water vapor in particular, are dependent on the quality of databases of spectral line parameters. There has been increasing scrutiny of databases such as HITRAN in recent years, but this has mostly been performed on a band-by-band basis. We report nine high-spectral-resolution (0.03 cm−1) measurements of the solar radiation reaching the surface in southern England over the wave number range 2000 to 12,500 cm−1 (0.8 to 5 μm) that allow a unique assessment of the consistency of the spectral line databases over this entire spectral region. The data are assessed in terms of the modeled water vapor column that is required to bring calculations and observations into agreement; for an entirely consistent database, this water vapor column should be constant with frequency. For the HITRAN01 database, the spread in water vapor column is about 11%, with distinct shifts between different spectral regions. The HITRAN04 database is in significantly better agreement (about 5% spread) in the completely updated 3000 to 8000 cm−1 spectral region, but inconsistencies between individual spectral regions remain: for example, in the 8000 to 9500 cm−1 spectral region, the results indicate an 18% (±1%) underestimate in line intensities with respect to the 3000 to 8000 cm−1 region. These measurements also indicate the impact of isotopic fractionation of water vapor in the 2500 to 2900 cm−1 range, where HDO lines dominate over the lines of the most abundant isotope of H2O.