研究目的
To develop a comprehensive calibration procedure for mobile, low-resolution, solar-absorption FTIR spectrometers used for greenhouse gases observations, ensuring their reliability for campaign use and deployment at remote sites.
研究成果
The study successfully developed a comprehensive calibration routine for mobile FTIR spectrometers, demonstrating their high level of stability and agreement. The method allows for the unambiguous detection of XGas enhancements in the sub-ppm range for CO2 and ppb range for CH4, making it suitable for detecting local sinks and sources of various kinds.
研究不足
The study acknowledges the need for a controlled environment for certain procedures to avoid condensation inside the spectrometer and the potential impact of local sources on measurements.
1:Experimental Design and Method Selection:
The study involved the characterization of the instrumental line shape (ILS) of each spectrometer by analyzing H2O signatures in open path spectra. A setup for an external source was suggested to demonstrate the invariance of derived ILS parameters with regard to chosen path length.
2:Sample Selection and Data Sources:
The study utilized open-path observations of lab air to derive ILS characteristics, avoiding the need for a gas cell. Side-by-side solar observations before and after a campaign were used to verify the temporal invariability of instrumental characteristics.
3:List of Experimental Equipment and Materials:
The study used portable FTIR spectrometers (EM27/SUN) developed in collaboration with Bruker, featuring a RockSolid? pendulum interferometer and an InGaAs detector.
4:Experimental Procedures and Operational Workflow:
The ILS was derived from H2O lines in the 7000 and 7400 cm?1 spectral region. The selected microwindow encompasses a large number of water vapor lines spanning a wide range of line intensities.
5:Data Analysis Methods:
The analysis used version 14 of the retrieval software LINEFIT for the ILS characterization and PROFFIT Version 9.6 for the spectral analysis.
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