Analysis of nonlinear effects in microwave spectrometers
Analysis of nonlinear effects in microwave spectrometers
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微波光谱仪的非线性效应分析
DOI：
10.1029/2008jd011141
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发表时间：
2009
影响因子：
--
通讯作者：
P. Hartogh
中科院分区：
文献类型：
--
作者：
L. Paganini;P. Hartogh
[1]在毫米波长下，行星大气中痕量气体的旋转光谱产生基本特征，如丰度、温度和风的垂直分布。外差光谱学提供的高分辨率允许以非常高的精度检索大气的化学成分和热结构。然而，在几次观测活动中，在外差光谱仪后端之间的功率谱密度（PSD）响应中观察到了小的意外差异。在这篇文章中，我们分析了非线性对这些观测的影响。这项调查涵盖两个主要主题。第一个目的是从理论上证明PSD精度的重要性，在观测下检索正确的地球物理参数。这项研究是通过辐射传输和检索模拟，这表明如何在光谱偏差可能会产生相当大的变化，在地球大气中检索的微量气体的垂直剖面。一旦PSD精度的重要性已经解决，第二个主题的重点是在光谱仪后端的非线性检测。基于差分方法，进行了一种精度比以前提高一个数量级以上的改进实验，以检测和研究啁啾变换光谱仪的非线性行为，从而评估优化其响应的可能机制。结果证实，由光谱仪中的非线性引入的总体偏差已经减小，并且因此后端仪器的性能已经改善。
[1] At millimeter wavelengths, rotational spectra of trace gases in planetary atmospheres yield essential characteristics such as vertical profiles of abundance, temperature, and winds. The high resolution provided by heterodyne spectroscopy allows to retrieve the chemical composition and thermal structure of the atmosphere with very high accuracy. On several observation campaigns, however, small unexpected differences have been observed in the power spectral density (PSD) response among heterodyne spectrometer backends. In this article, we analyze what the impact of nonlinearity is on these observations. This investigation covers two major topics. The first one seeks to theoretically demonstrate the importance of PSD accuracy for retrieving the correct geophysical parameters under observation. This study is performed by means of radiative transfer and retrieval simulations, which show how deviations in the spectra might produce considerable changes in the vertical profile of trace gases retrieved in the Earth's atmosphere. Once the importance of PSD accuracy has been addressed, the second topic focuses on the detection of nonlinearity in spectrometer backends. On the basis of a differential approach, an improved experiment with more than one order of magnitude higher accuracy than before was conducted in order to detect and study nonlinear behavior in chirp transform spectrometers and, consequently, evaluate possible mechanisms to optimize their response. As a result, it is confirmed that the overall deviations introduced by nonlinearity in spectrometers have been decreased, and thus the performance of the backend instrument has been improved.
中高纬度中上层中间层冬季臭氧昼夜比异常研究
影响因子：
2.6
作者：
G. R. Sonnemann;P. Hartogh;C. Jarchow;M. Grygalashvyly;U. Berger
通讯作者：
U. Berger