Using satellite (MODIS) and reanalysis (MERRA-2) data from 2004 to 2024, this study examines the spatiotemporal variability and long-term trends of aerosol optical depth (AOD) over Ethiopia. Both datasets were evaluated against in-situ AERONET measurements to assess their accuracy and suitability. MERRA-2 and MODIS show strong and moderate correlations with AERONET AOD (r = 0.76 and r = 0.64, respectively), confirming their robustness for characterizing Ethiopia’s aerosol environment. Validation of OMI data showed a weaker correlation ( \(r=0.32\) ), while composite analysis revealed a modest impact of climate modes (ENSO/IOD) on regional AOD anomalies, with negative anomalies during ENSO phases. Total AOD at 550 nm (TAOD) exhibits a clear seasonal wet-dry cycle, with lower values (<0.14) during the wet season and higher values (>0.30) during the dry season, peaking in June. Spatially, the central highlands and western lowlands show decreased aerosol loading because of efficient wet scavenging and vegetation cover, while the desert Afar region continues to have significant aerosol burdens caused by mineral dust uplift. Regional differences in aerosol sources and climatic conditions are reflected in correlation analyses between absorbing AOD at 500nm (AAOD) and key meteorological variables. Correlation analyses between absorbing AOD at 500 nm (AAOD) and key meteorological variables show strong AAOD–temperature relationships in the northeast (R \(^2\) = 0.66, p = 0.0013) and northwest (R \(^2\) = 0.59, p = 0.0033), moderate relationships in the southwest (R \(^2\) = 0.52, p = 0.0062), and weak relationships in the southeast (R \(^2\) = 0.10, p = 0.2807). AAOD–precipitation correlations range from moderate (northeast R \(^2\) = 0.43, p = 0.0203) to weak (southwest R \(^2\) = 0.07, p = 0.6466), and are non-significant in the southeast (R \(^2\) = 0.15, p = 0.1136). In wetter regions, scattering AOD at 550 nm (SAOD) exhibits a positive association with precipitation (northeast R \(^2\) = 0.29; northwest R \(^2\) = 0.10), while correlations are negligible in arid zones. Using the Sen’s slope estimator and the Mann-Kendall test, the long-term analysis shows that national-scale trends in TAEOD, SAOD, AAOD, and TAOD are generally weak and statistically insignificant. Although spatial maps reveal localized increasing trends, particularly in the arid regions of northeastern Ethiopia, these do not translate into significant national trends, which remain dominated by strong interannual variability. The impact of regional circulations on dust uplift and aerosol transport is further demonstrated by wind streamline analyses conducted at 850 and 1000 hPa, especially over the northern and eastern sectors. Together, these findings show that episodic emission events and seasonal meteorological-dynamics, rather than long-term, persistent changes, dominate Ethiopia’s aerosol regime. This highlights the need for improved high-resolution monitoring and modeling, as well as localized emission control strategies, to inform climate and air quality policy.
