A new ground-based FTIR spectrometer reference site at Shadnagar (India) and preliminary columnar retrievals of CH4 and N2O. Issue 14 (18th July 2017)

• Record Type: Journal Article
• Authors: Mahesh, P.; Biswadip, G.; Rao, P. V. N.; Dadhwal, V. K.; Sreenivas, G.; Kanchana, A. L.; Mallikarjun, K.
• Is Part Of: International journal of remote sensing. Volume 38:Issue 14(2017)
• Page Start: 4033
• Page End: 4046
• Publication Date: 2017-07-18
• Subjects: Remote sensing -- Periodicals; Télédétection -- Périodiques; 621.3678
• DOI: 10.1080/01431161.2017.1312624
• Languages: English
• ISSNs: 0143-1161

Abstract

ABSTRACT: A Fourier Transform Infrared (FTIR) spectrometer has been operational since March 2014, at National Remote Sensing Centre (NRSC), Shadnagar, which is a suburban site of central India. Direct solar radiation spectra recorded by the FTIR during clear sky days at a high spectral resolution of 0.01 cm ‒1 were analysed using the line-by-line radiative transfer algorithm (LBLRTA) to retrieve the initial results of column-averaged concentrations of methane (XCH4 ) and nitrous oxide (XN2O ) in the atmosphere. Error residuals between the measured and estimated atmospheric transmissions are in the range of 0.40–0.80% for CH4 and 0.20–0.50% for N2 O, respectively. The maximum (minimum) XCH4 and XN2O were, respectively, 1.88 ± 0.04 ppm (1.67 ± 0.02 ppm) and 316.15 ± 5.85 ppb (278.92 ± 4.02 ppb). Columnar concentrations of CH4 and N2 O retrieved from the Infrared Atmospheric Sounding Interferometer (IASI) were compared against retrieved XCH4 and XN2O using the ground FTIR. The observed differences between the two data sets lie between −0.06 ppm and +0.10 ppm for CH4 and between +32 ppb and ‒10 ppb for N2 O.