On the efficient treatment of temperature profiles for the estimation of atmospheric transmittance under scattering conditions
On the efficient treatment of temperature profiles for the estimation of atmospheric transmittance under scattering conditions
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DOI：
10.5194/amt-5-2525-2012
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发表时间：
2012-10
影响因子：
3.8
通讯作者：
R. Lindstrot;R. Preusker
中科院分区：
文献类型：
--
作者：
R. Lindstrot;R. Preusker
摘要。大气的垂直温度分布对气体吸收谱线的宽度和强度有影响。在光谱的可见和近红外部分，这给辐射传输的快进模拟带来了问题，这是从卫星测量中检索任何大气或地面相关参数所需的算法。通过对来自全球预报系统（GFS）的全球温度曲线集进行主成分分析（PCA），我们发现，根据精度要求，温度曲线的全球变率的主要部分可以用它们的前2到6个特征向量来描述。此外，我们证明了通过归因于每个显著温度特征向量的透射率的线性组合近似O2 A波段任何温度剖面的大气透射率的可能性，并且具有几乎完美的精度。对于从O2 A波段测量数据中检索地表压力，通过在平均温度剖面假设下强烈降低地表压力的区域偏差，将全球均方根误差从30hpa降低到1hpa以下。该技术可以在散射条件下应用，以消除温度引起的误差，例如，模拟辐射。原则上，该方法可用于任何问题，包括对温度剖面有重大影响的气体吸收或排放，例如总水蒸气含量或海面温度的检索。
Abstract. The vertical temperature profile of the atmosphere has an influence on the width and intensity of gaseous absorption lines. In the visible and near infrared part of the spectrum, this poses a problem for the fast forward simulation of the radiative transfer, needed in algorithms for the retrieval of any atmospheric or surface-related parameter from satellite measurements. We show that the main part of the global variability of temperature profiles can be described by their first 2 to 6 eigenvectors, depending on the accuracy requirement, by performing a Principal Component Analysis (PCA) on a global set of temperature profiles from the Global Forecast System (GFS). Furthermore, we demonstrate the possibility to approximate the atmospheric transmittance in the O2 A band for any temperature profile with almost perfect accuracy by a linear combination of the transmittances attributed to each of the significant temperature eigenvectors. For the retrieval of surface pressure from O2 A band measurements, this reduces the global root mean square error from >30 hPa to better than 1 hPa by strongly reducing the regional bias of surface pressure, retrieved on the assumption of an average temperature profile. The technique can be applied under scattering conditions to eliminate temperature-induced errors in, e.g., simulated radiances. In principal, the method can be useful for any problem including gaseous absorption or emission with a significant influence of the temperature profile, such as the retrieval of total water vapour content or sea surface temperature.