A ground-based high spectral resolution Fourier-transform infrared (FTIR) solar absorptionrnspectrometer has been operational at the Addis Ababa University (9.01â—¦ N, 38.76â—¦ E, 2443rnm a.s.l) since May 2009 to obtain information on the total column abundances and verticalrndistribution of various constituents in the atmosphere. Retrieval strategy and resultsrnon information content and corresponding full error budget evaluation of methane and nitrousrnoxide are presented. Optimal estimation retrieval technique is used to analyses thernobserved spectra and provide regular vertical profiles, total and partial column measurementsrnof trace gases. The volume mixing ratio profiles of CH4 and N2O are simultaneouslyrnretrieved from ground-based FTIR solar absorption spectra measured between Mayrn2009 and March 2013. The ground-based FTIR CH4 and N2O at Addis Ababa, Ethiopiarnwere compared with Michelson Interferometer for Passive Atmospheric Sounding ( MIPAS)rn(version V5R_CH4_220, V5R_CH4_224, V5R_N2O_220 and V5R_N2O_224), thernMicrowave Limb Sounder on board of the Aura satellite (Aura/MLS) (MLS v3.3 of N2Ornand CH4 derived from MLS v3.3 products of CO, N2O and H2O) and the Atmospheric InfraredrnSounder (AIRS) (CH4) to validate the instrument performance. Relative differencesrnrange in vertical profiles of CH4 and N2O from the measurements between MIPAS (versionrnV5R_CH4_220, V5R_CH4_224, V5R_N2O_220 and V5R_N2O_224) and FTIR inrnaltitude ranges of 15-27 km are -15 % to -3.8 %, -4.8 % to 4.6 %, 2 % to 10 %, -7 % to 15rn% respectively. Moreover, the mean differences in partial column of CH4 and N2O withinrnaltitude ranges of 15 to 27 km are -11 % , -5.5 %, 2.39 % and 0.5 % respectively. Relativerndifferences in vertical profiles of CH4 and N2O from the measurements between MLS v3.3rnand FTIR in altitude ranges of 17-27 km are less than 9 % and 15 % respectively. Relativerndifferences range in vertical profiles of CH4 from the measurements between AIRS andrnFTIR in altitude ranges of 11-27 km is -4.8 % to 9 %. The bias obtained between FTIRrnand the new data version of MIPAS_CH4_224 has been reduced in the altitude range ofrn15-27 km when the interfering gas H2O is fitted jointly with the target gas, CH4. Therefore,rnthe ground-based FTIR spectrometer can be recommended for CH4 and N2O satellite datarn(MIPAS, MLS and AIRS) validation.rnUncertainties of tropical methane concentrations, retrieved from spectra recorded by thernMIPAS, MIPAS_CH4_220 are large at upper troposphere and lower stratosphere. The relationrnof these uncertainties with water vapour variability is explored and the uncertaintiesrnhave been reduced in MIPAS_CH4_224. Coincident measurements of CH4 by MIPAS,rnground based FTIR and EOS MLS CH4 are used to estimate the standard uncertainty of MIPAS_CH4_220, MIPAS_CH4_224 and natural variability of H2O. Different methods suchrnas bias evaluation, differential method and correlation coefficient are employed to explorernthe latitudinal variations of standard uncertainty of MIPAS_CH4_220 and natural variabilityrnof water vapour as well as its reduction in MIPAS_CH4_224. The averaged bias betweenrnMIPAS_CH4_220 and ground-based FTIR measurements in the altitude range 15-22 kmrnare 12.3 %, 8.9 % and -1.2 % for the tropics, mid-latitudes and high latitudes, respectively.rnWhereas the averaged bias for MIPAS_CH4_224 is 3.4 %, -2.8 % and -2.4 %. The averagernestimated uncertainties of MIPAS_CH4_220 methane are 5.9 %, 4.8 % and 4.7 % at altitudernranges of 15 to 27 km in the tropics, mid-latitudes and high latitudes, respectively. On thernother hand, the average estimated uncertainties of MIPAS_CH4_224 methane were obtainedrn2.4 %, 1.4 % and 5.1 %. Moreover, the correlation coefficient between MIPAS_CH4_220rnand MIPAS_N2O_220 are found to be 0.30, 0.98 and 0.96 in the lower stratosphere of therntropics, mid and high latitudes respectively. However, the correlation coefficient betweenrnMIPAS_CH4_224 and MIPAS_N2O_224 are 0.62, 0.80 and 0.66. The correlation coefficientrnbetween the uncertainty of MIPAS_CH4_220, MIPAS_CH4_224 and the variability ofrnwater vapour in the lower stratosphere are 0.70 and 0.51 on monthly temporal scales. It wasrnfound that the relation between the uncertainty in methane and the variability of water vaporrnhas been reduced in the new data version. Therefore, the natural variability of water vapourrnwas a cause for high uncertainties in the MIPAS_CH4_220 measurements over tropics.rnIn summary, this study has derived column abundances and profiles of CH4 and N2Ornfrom solar absorption measurements taken by FTIR at tropical high altitude site of AddisrnAbaba, Ethiopia for a period that covers May 2009 to March 2013. The quality of the datarnis assessed through comparison with data from MIPAS, MLS and AIRS sensors onboardrnsatellites. Moreover, the different retrieval errors and their sources are fully characterized tornallow the use of the data in further scientific studies as it represents unique environment ofrntropical Africa, a region poorly investigated in the past.