Open Access Digital Repository of Ministry of Earth Sciences, Government of India

Analysis of sunlight absorption spectra related to atmospheric trace gases in the tropics

Meena, GS and Lal, DM (2016) Analysis of sunlight absorption spectra related to atmospheric trace gases in the tropics. International Journal of Remote Sensing, 37 (6). pp. 1362-1375.

Full text not available from this repository. (Request a copy)

Abstract

Zenith sky-scattered light intensity spectra of wavelength ranges of 325–500 nm have been recorded with UV-visible spectrometer over tropical station Pune (18° 31′ N, 73° 55′ E). Zenith scattered light spectra in the spectral range of 346–358 nm are analysed to find out differential optical depth (DOD) for the period 15–18 November 2010. In DOD spectra, depths are noticed at relevant wavelength due to the absorption by atmospheric gases such as NO2 (nitrogen dioxide), O3 (ozone), BrO (bromine monoxide), and OClO (chlorine dioxide). These DOD spectra are analysed by a matrix inversion technique to calculate individual DOD spectrum of the gases. The observed and calculated DODs are found to be in a good agreement. The coefficient of determination (R2) between observed and calculated DODs of NO2, O3, BrO, OClO, O4 (oxygen dimer), and Ring effect are observed to be 0.55, 0.77, 0.73, 0.75, 0.82, and 0.91, respectively. Filling-in of solar Fraunhofer lines in the observed zenith scattered sunlight is known as ‘Ring effect’. The slant column densities of the above gases are found to be increased due to increasing absorption path length with solar zenith angles. The vertical column densities (VCDs) of O3 and NO2 derived using ground-based spectrometer are compared with the Ozone Monitoring Instrument (OMI) on board Aura satellite during the period 1 March–31 December 2010. The day-to-day variations are found to be similar; however, the percentage differences in VCDs of O3 between ground-based spectrometer and satellite-based OMI are observed to be varying from 1% to 15%, while for NO2, they vary from 1% to 10%. Also, the seasonal mean values of VCDs of O3 and NO2 are discussed. The O3 mean values in the rainy season are found to be higher than that of in the summer and winter seasons from both ground- and satellite-based measurement. Whereas, the NO2 mean values in the winter season are found to be higher than that of in the summer and rainy seasons from both the measurement techniques. The VCDs of O3 are observed to be lowest in winter season due to the loss of ozone within NO2 and O3 reaction active during the winter season.

Item Type: Article
Additional Information: Copyright of this article belongs to Taylor & Francis Group
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 08 Apr 2017 08:56
Last Modified: 08 Apr 2017 08:56
URI: http://moeseprints.incois.gov.in/id/eprint/4334

Actions (login required)

View Item View Item