The issues of climate change and its causes have become agenda of di erent governmentalrnand non-governmental discussions. The major atmospheric components responsible forrnclimate change are particulate matters (aerosols) and trace gases (mainly anthropogenicrngreen house gases). The stratospheric aerosol climatology over Ethiopia from SAGE IIrndata and carbonyl sul de (OCS) measurement from FTIR spectrometer over Addis Ababarnare discussed in this thesis. The vertical pro les of aerosol extinction over Ethiopia werernanalyzed and the result shows seasonal variation of stratospheric aerosol distribution overrnEthiopia. The total column stratospheric aerosol also shows seasonal variation with maximumrnvalue attained during Spring and minimum during Summer. The annual meanrnvalue of total column AOD is observed to be steadily increasing from 1984 to 2005, whichrnrevealed the increasing trend of stratospheric aerosols of both ne and course mode particles.rnResults from the monthly mean stratospheric aerosol size distribution show thatrnthe number density is maximum for months of maximum AOD values as expected howeverrnthe observed trend is not signi cant. The Bruker IFS120M was installed at tropicalrnsite located in Addis Ababa, Capital of Ethiopia (9o10 ; 38o760 ; 2443 m.a.s.l.) and hasrnbeen continuously operating since May, 2009. Nearly regular cell (HBr cell) measurementsrnwere taken using laboratory source to monitor the alignment of the instrumentrnand its stability over time. The analysis of cell measurement using LINEFIT (LINEFIT12)rnsoftware has indicated the performance of the instrument is very good. The datarnmeasured between May, 2009 to April, 2010 were analyzed and interpreted. The latestrnversion of PROFFIT (PROFFIT95) was used to retrieve vertical pro les and totalrncolumn values of carbonyl sul de from pressure dependent broadened spectra with thernhelp of Tikhonov-Philips regularization method. The OCS VMR observed at Addis siternreaches up to 0.6 parts per billion by volume (ppbv) and the total column amount reachesrnup to 8 1019 molecules=cm2. The total column and vertical pro le observed in ourrnxirnsite is greater than the same quantity reported at Izana, Spain. The tropospheric andrnstratospheric mass of OCS is also estimated in gram and we found it to be 4.6056 Tg andrn0.3427 Tg respectively which sum up to yield of 4.9484 Tg of total mass. The atmophericrnlife time of OCS in our region is estimated to be 4.1236 years. Because of its longerrnlife time in the atmosphere (as compared to other sulfur containing compounds), it isrntransported to the stratosphere through the tropical tropopause by di erent mechanismsrnand latter converted to form stratospheric background sulfate aerosol layer, which in turnrndetermines the Earth's radiation budget. Random and systematic Error contributionrnto retrieval were analyzed and the result shows that the total error contribution due tornatmospheric and auxiliary parameters is less than 10%