Measurement of atmospheric carbon dioxide and water vapor in built-up urban areas in the Gandhinagar-Ahmedabad region in India using a portable tunable diode laser spectroscopy system

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dc.contributor.author Roy, Anirban
dc.contributor.author Sharma, Neetesh Kumar
dc.contributor.author Chakraborty, Arup Lal
dc.contributor.author Upadhyay, Abhishek
dc.date.accessioned 2017-09-19T10:21:24Z
dc.date.available 2017-09-19T10:21:24Z
dc.date.issued 2017-11
dc.identifier.citation Roy, Anirban; Sharma, Neetesh Kumar; Chakraborty, Arup Lal and Upadhyay, Abhishek, “Measurement of atmospheric carbon dioxide and water vapor in built-up urban areas in the Gandhinagar-Ahmedabad region in India using a portable tunable diode laser spectroscopy system”, Applied Optics, DOI: 10.1364/AO.56.000H57, vol. 56, no. 31, pp. H57-H66, Nov. 2017. en_US
dc.identifier.issn 1559-128X
dc.identifier.issn 2155-3165
dc.identifier.uri http://dx.doi.org/10.1364/AO.56.000H57
dc.identifier.uri https://repository.iitgn.ac.in/handle/123456789/3142
dc.description.abstract This paper reports open-path in situ measurements of atmospheric carbon dioxide at Gandhinagar (23.2156°N, 72.6369°E) and Ahmedabad (23.0225°N, 72.5714°E) in the heavily industrialized state of Gujarat in western India. Calibration-free second harmonic wavelength modulation spectroscopy (2𝑓2f WMS) is used to carry out accurate and fully automated measurements. The mean values of the mole fraction of carbon dioxide at four locations were 438 ppm, 495 ppm, 550 ppm, and 740 ppm, respectively. These values are much higher than the current global average of 406.67 ppm. A 1 mW, 2004-nm vertical cavity surface-emitting laser is used to selectively interrogate the R16 transition of carbon dioxide at 2003.5 nm (4991.2585 cm−1). The 2𝑓2f WMS signal corresponding to the gas absorption line shape is simulated using spectroscopic parameters available in the HITRAN database and relevant laser parameters that are extracted in situ from non-absorbing spectral wings of the harmonic signals. The mole fraction of carbon dioxide is extracted in real-time by a MATLAB program from least-squares fit of the simulated 2𝑓2f WMS signal to the corresponding experimentally obtained signal. A 10-mW, 1392.54-nm distributed feedback laser is used at two of the locations to carry out water vapor measurements using direct absorption spectroscopy. This is the first instance of a portable tunable diode laser spectroscopy system being deployed in an urban location in India to measure atmospheric carbon dioxide and water vapor under varying traffic conditions. The measurements clearly demonstrate the need to adopt tunable diode laser spectroscopy for precise long-term monitoring of greenhouse gases in the Indian subcontinent. en_US
dc.description.statementofresponsibility by Anirban Roy, Neetesh Kumar Sharma, Arup Lal Chakraborty and Abhishek Upadhyay.
dc.format.extent vol. 56, no. 31, pp. H57-H66
dc.language.iso en en_US
dc.publisher Optical Society of America en_US
dc.title Measurement of atmospheric carbon dioxide and water vapor in built-up urban areas in the Gandhinagar-Ahmedabad region in India using a portable tunable diode laser spectroscopy system en_US
dc.type Article en_US
dc.relation.journal Applied Optics


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