Observation and Validation of Methane from FT-IR over Addis Ababa.

Gemechu, Endale (2011) Observation and Validation of Methane from FT-IR over Addis Ababa. Masters thesis, Addis Ababa University.

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The concentration of methane, the most abundant organic trace gas in the atmosphere has increased dramatically, over the past few centuries, to more than double its value. The increase in its concentration is of special concern because of its effects on climate and atmospheric chemistry. High resolution Mid infra-red (MIR) solar absorption FTIR spectra have been routinely recorded between May 2009 and Nov 2010 at Addis Ababa Observatory (9.01oN, 38.76oE). By analyzing the shape of the pressure dependent absorption lines and their different temperature sensitivities, the vertical distribution and column amount of methane is retrieved. Unique time series of the column abundances and volume mixing ratio (vmr) of methane are presented. The effects of both dynamical and chemical seasonally varying trace gas cycles can be seen in the retrieved profiles. These include little variabilities in summer and winter seasons, which is typical of tropical atmosphere. Particular events are selected and origin of air mass flow is identified with the help of Air Resource Laboratory’s (ARL) Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. A detailed error analysis has been performed for each profile. The output from Atmospheric Infra-Red Sounder (AIRS) is compared to the total column amount. Results agree well with a correlation coefficient of 0.8.

Item Type: Thesis (Masters)
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Q Science > QD Chemistry
Divisions: Africana
Depositing User: Selom Ghislain
Date Deposited: 29 Jun 2018 07:35
Last Modified: 29 Jun 2018 07:35
URI: http://thesisbank.jhia.ac.ke/id/eprint/6119

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