Spectroscopic Measurements of Tropospheric HCN and C2H6 over Addis Ababa
No Thumbnail Available
Date
2011-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The atmospheric concentrations of HCN and C2H6 are important indicators of tropospheric
pollution and transport because they are primarily emitted from biomass burning
and anthropogenic sources. Tropospheric column amounts and mixing ratios of C2H6
and HCN were retrieved from ground-based infrared solar spectra using a vertical pro le
retrieval algorithm (PROFFIT). The spectra were recorded with high spectral resolution
Fourier transform infrared (FTIR) spectrometer at Addis Ababa (9.010 N, 38.760 E and
2.45 km asl), Ethiopia from May 2009 to February 2011. The selected microwindows are
found to be good with a maximum residual error of less than 0.1% for HCN and less than
3.5% for C2H6 retrievals. We found that the degrees of freedom for HCN is 2 and 1.5
for C2H6 with a total statistical error 38.78% and 17.74% and a total systematic error
37.33% and 12.04% respectively. HCN is more sensitive in the upper atmosphere while
C2H6 is sensitive in the lower atmosphere. The total column amount of HCN ranges from
9.83 1018 to 6.39 1019 while of C2H6 from 3.60 1019 to 1.70 1020 molecules/m2. The
maximum volume mixing ratio for both gases was found in March
Description
Keywords
Spectroscopic Measurements