Laser heterodyne radiometers (LHR) for in situ ground-based remote sensing of greenhouse gases in the atmospheric column
Authors: Wang Jingjing , Shen Fengjiao , Tan Tu , Cao Zhensong , Gao Xiaoming , Jeseck Pascal , Te Yao , Chen Weidong 
Published: March 2020

&lt;p&gt;Measurements of vertical concentration profiles of greenhouse gases (GHGs) is extremely important for our understanding of regional air quality and global climate change trends. In this context, laser heterodyne radiometer (LHR) technique has been developed &lt;sup&gt;[1-5]&lt;/sup&gt; for ground-based remote measurements of GHGs in the atmospheric column.&lt;/p&gt;&lt;p&gt;Solar radiation undergoing absorption by multi-species in the atmosphere is coupled into a LHR instrument where the sunlight is mixed with a local oscillator (LO), being usually a tunable laser source, in a fast photodetector. Beating note at radio frequency (RF) resulted from this photomixing contains absorption information of the LO-targeted molecules. Scanning the LO frequency across the target molecular absorption lines allows one to extract the corresponding absorption features from the total absorption of the solar radiation by all molecules in the atmospheric column. Near-IR (~1.5 &amp;#181;m) and mid-IR (~8 &amp;#181;m) &lt;sup&gt;[6]&lt;/sup&gt; LHRs have been recently developed in the present work. Field campaigns have been performed on the roof of the platform of IRENE in Dunkerque (51.05&amp;#176;N/2.34&amp;#176;E).&lt;/p&gt;&lt;p&gt;The developed LHR instruments as well as the preliminary results of their applications to the measurements of CH&lt;sub&gt;4&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, CO&lt;sub&gt;2&lt;/sub&gt; (including &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt;/&lt;sup&gt;12&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt;), H&lt;sub&gt;2&lt;/sub&gt;O vapor (and its isotopologue HDO) in the atmospheric column will be presented and discussed.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgments&lt;/strong&gt; The authors thank the &amp;#64257;nancial supports from the LABEX CaPPA project (ANR-10-LABX005), the MABCaM (ANR-16-CE04-0009) and the MULTIPAS (ANR-16-CE04-0012) contracts, as well as the CPER CLIMIBIO program. S. F. thanks the program Labex CaPPA and the &quot;P&amp;#244;le M&amp;#233;tropolitain de la C&amp;#244;te d&amp;#8217;Opale&quot; (PMCO) for the PhD fellowship support.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References &lt;/strong&gt;&lt;/p&gt;&lt;p&gt;[1] R. T. Menzies, and R. K. Seals, Science &lt;strong&gt;197&lt;/strong&gt; (1977) 1275-1277&lt;/p&gt;&lt;p&gt;[2] D. Weidmann, T. Tsai, N. A. Macleod, and G. Wysocki, Opt. Lett. &lt;strong&gt;36&lt;/strong&gt; (2011) 1951-1953&lt;/p&gt;&lt;p&gt;[3] E. L. Wilson, M. L. McLinden, and J. H. Miller, Appl. Phys. B &lt;strong&gt;114&lt;/strong&gt; (2014) 385-393&lt;/p&gt;&lt;p&gt;[4] A. Rodin, A. Klimchuk, A. Nadezhdinskiy, D. Churbanov, and M. Spiridonov, Opt. Express &lt;strong&gt;22&lt;/strong&gt; (2014) 13825-13834&lt;/p&gt;&lt;p&gt;[5] J. Wang, G. Wang, T. Tan, G. Zhu, C. Sun, Z. CAO, W. Chen, and X. Gao, Opt. Express &lt;strong&gt;27&lt;/strong&gt; (2019) 9600-9619&lt;/p&gt;&lt;p&gt;[6] F. Shen, P. Jeseck, Y. Te, T. Tan, X. Gao, E. Fertein, and W. Chen, Geophys. Res. Abstracts, &lt;strong&gt;20 &lt;/strong&gt;(2018) EGU2018-79&lt;/p&gt;