Abstract
Greenhouse gasses (GHGs) play an important role in controlling local air
pollution as well as climate change. In the present study, we retrieved
column-averaged dry-air (X) mole fractions of carbon dioxide (CO2),
methane (CH4), and carbon monoxide (CO) using a ground-based EM27/SUN
Fourier Transform Infrared Spectrometer (FTIR). The EM27/SUN
spectrometers are widely in use in the COllaborative Carbon Column
Observing Network (COCCON). The PROFFAST software provided by COCCON has
been used to analyze the measured atmospheric solar absorption spectra.
In this paper, the diurnal variation and the time series of daily
averaged XCO2, XCH4, and XCO covering the period December 2020 to May
2021 are analyzed. The maximum values of XCO2, XCH4, and XCO are
observed to be 420.57 ppm, 1.93 ppm, and 170.40 ppb respectively. Less
diurnal (XCO2 ~0.44 ppm; XCH4=0.004 ppm, and XCO=4.84
ppb) but clear seasonal changes are observed during the study period.
The XCH4 and XCO from the Sentinel-5Precursor (S5P)/TROPOspheric
Monitoring Instrument (TROPOMI) are compared against the EM27/SUN
retrievals. The correlation coefficient ‘r’ between the EM27/SUN
retrieved XCH4 and XCO against S5P/TROPOMI are 0.75 and 0.94
respectively.