Correlation of aerosol particles with clouds and radiation budget over the horn of Africa–Ethiopia using MODIS satellite data: Part 02

The aerosol particles are positively associated with the cloud parameters, precipitation and radiation budgets. The correlations of the aerosols-clouds-precipitations interaction ACPI are uncertain, that show large spatiotemporal variability in their magnitude. For this study, the aerosol particles and clouds data were retrieved from the Moderate Resolution Imaging Spectroradiometer MODIS sensors. These comprized of aerosol optical depth AOD, Ångström exponential AET, atmospheric water vapor AWV, mean cloud fraction CFM, cloud top pressure CTP and cloud top temperature CTT. The precipitation PPT data is comprized of 3B43 monthly products sourced from Tropical Rainfall Measuring Mission TRMM and the outgoing long-wave radiation OLR flux is comprized of Clouds and the Earth‘s Radiant Energy System CERES satellite instruments.

The study covers sixteen sites in East Africa–Ethiopia with neighboring Eritrea, Djibouti, and South Sudan countries clustered into four regions for the periods 2001–2022 to provide detailed information on the aerosol particles spatiotemporal correlations on clouds and precipitation. The increase–decrease AET, AWV, CFM and PPT fluctuations are with AOD opposing OLR, CTP and CTT. The spatial correlations are oriented towards western part mostly in southwest of the study area regions. The clustered regions show minima radiative forcing in 2012 at the southwest cluster for all surface radiative forcing F${}_{\text{Surf}}$ and at the southeast cluster for top of the atmosphere radiative forcing F${}_{\text{TOA}}$, with their maxima at the northwest cluster in 2022 for F${}_{\text{Surf}}$ and in 2010 for F${}_{\text{TOA}}$ from both instruments. Accordingly, the minimum values are −23.83 Wm⁻² and 8.37 Wm⁻² for Terra and −22.95 Wm⁻² and 7.68 Wm⁻² for Aqua, and the maxima are −0.58 Wm⁻² and 63.80 Wm⁻² for Terra −1.37 Wm⁻² and 58.83 Wm⁻² for Aqua, respectively. Here, the values for all of the parameters we observed in the Terra satellite are mostly greater than those of the Aqua satellite. The values for the parameters were higher in the southern clusters, specifically in the southwest clusters, than in the northern clusters.

The mean cloud fraction CFM was less dominant, while AET was the most dominant variable with 0.02733$<$ slop value ${\beta }_1<15.17547$ in the regression analysis. The study area regions showed the best performance R values, with 0.93941 $<$ R $<$ 0.99958 for all the seasons. The minimum values observed in Bega at Kombolcha are from Aqua for both ${\beta }_1$ and R, while their maximums are from Terra in Kiremt at Bahir Dar for the dominance and in Tseday at Agnuak for the performance we described.