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Soil moisture data is crucial for enhancing drought monitoring, optimizing water management, refining irrigation schedules, forecasting floods, and understanding climate change impacts. Despite the existence of long-term global satellite and reanalysis products, the performance of global satellite products in Ethiopia is underexplored, highlighting a need for comprehensive assessments to effectively utilize these resources and address critical environmental challenges. This research evaluates various operational satellites and reanalysis soil moisture datasets over the Gilgel Abay watershed. The datasets include the European Space Agency's Climate Change Initiative Soil Moisture (ESA-CCI SM), Soil Moisture and Ocean Salinity (SMOS), NASA's Soil Moisture Active Passive mission (SMAP Enhanced), the European Centre for Medium-Range Weather Forecasts Fifth Generation Reanalysis (ECMWF ERA5), Climate Forecast System reanalysis (CFSRv2), NASA's Short-term Prediction Research and Transition Center - Land Information System (SPoRT-LIS), and NASA's Global Land Data Assimilation System (GLDAS). After applying bias correction, the Kolmogorov-Smirnov two-sample t-tests, Bonferroni correction, and statistical error metrics, the evaluation reveals that all products, except NASA-GLDAS, effectively capture soil moisture dynamics. SMAP shows superior temporal dynamics, followed by SMOS, ESA-CCI, CFSRv2, LIS and ERA5. Using Spearman's rank correlation coefficient (rs), SMAP (rs = 0.68) and SMOS (rs = 0.67) identified as the most accurate soil moisture products, with SMOS excelling in spatial representation and closely aligning with the Topographic Wetness Index (TWI). However, the lack of sufficient in situ monitoring networks limits the ability to perform a thorough evaluation. Establishing these networks is essential for improving satellite retrievals and modelling in the upper Blue Nile Basin, Ethiopia.

Study region: The eastern flank of the 4 km Rwenzori Mountains and the Mobuku catchment 0.25–0.4 N, 29.85–30.1E are the geographic area for detailed analysis. Research focus: Hydro-climate variability is studied using high resolution satellite- and model- assimilated products in the period 1980–2023. The Mobuku catchment receives rainfall of 3–6 mm/day which generates an eastward discharge of 100 m3/s that declines rapidly downstream, thereby limiting hydro-power availability. New insights: Long-term trends in cloud fraction and potential evaporation reveal a tendency for drying associated with increasing easterly winds, subsidence near the mountain top, and warming of +.04 C/year that is melting glaciers. These constrain runoff on the eastern flank of the Rwenzori Mountains. Low river flows in Dec-Mar correspond with dry air intrusions from the northeast. High river flows in Jul-Nov are modulated by sea temperatures in the Indian Ocean that oscillate east-west at ∼3 year interval. Improved understanding of climate variability will contribute to better management of Uganda’s hydro-power resources.

Study region: Tana basin is the origin of the Blue Nile Basin located in Ethiopia. The Lake Tana’s mean annual precipitation is approximately 1400 mm/yr and its outflow drains an area of about 15,096 km2. There is limited effort to apply nested hydrological models for flood prediction due to being poorly gauged for validation. Study focus: The objective of this study is to show how climate simulations can be used to generate reliable local predictions of flood and runoff for the Blue Nile in the Ethiopian highlands.In this study, outputs from the Coupled Model Intercomparison Project Phase 6 (CMIP6) were used to initialize a nested hydrological model to reveal long-term trends of runoff in flood-prone areas of the Lake Tana basin, Ethiopia. Available satellite and reanalysis datasets were used for selection of CMIP6 products and the five models with best validation were used to force a nested hydrological model: Known as Wflow_sbm. A model-independent multi-algorithm optimization estimation tool was implemented for calibration of Wflow with insitu observations. New hydrological insights for the region: In terms of simulating runoff and flood events, application of Wflow_sbm to the Lake Tana basin gave promising results. This study serves as a major step towards the development and implementation of global model-driven nested hydrological assessments of flood risk in future projections for Lake Tana basin.

Drought is a slow onset, recurring and inevitable feature of South Africa's climate. This research deconstructs the meteorological processes underlying drought and its impacts on surface temperature and vegetation in the more productive eastern half of South Africa. We use an index area 22–31°S, 22–32°E and extract monthly satellite and reanalysis data in the period 1979–2019. Drought intensity is determined by i) vegetation color, ii) soil moisture, iii) maximum air temperature and iv) net outgoing longwave radiation. Global drivers are represented by tropical Pacific and Indian Ocean sea temperatures. Composite and regression analysis of drought reveals a mid-tropospheric anticyclone over Namibia induces equatorward flow and subsidence that drives away atmospheric moisture. This feature is associated with the Pacific El Niño, positive Indian Ocean Dipole and an accelerated westerly jet stream. Ocean warming east of Madagascar draws NW-cloud bands there. The advection of anticyclonic vorticity from the South Atlantic and standing atmospheric Rossby wave-trains are key features of South African drought. Dry spells in the summers of 2015, 2016 and 2019 were more intense than 1983 and 1992, as reflected by S-pan potential evaporation measurements >14 mm/day. Despite water deficits, maize yields and river discharge appear stable, due to the uptake of scientific advice and innovative engineering.

Using ozone data from model-assimilated satellite measurements in the eastern Caribbean 15–20N, 60–68W, cases were studied when upper tropospheric O3 values declined below 60 ppb. Secondary criteria on convection and circulation isolated two hurricanes for analysis (Irma and Maria 2017). Winds at 150 hPa (14 km) show divergence over the vortex characterized by ozone 100 ppb appear west of hurricanes, where sinking motions interact with vortex outflow. Past work suggests that high values are important, but here low ozone concentrations near the core are more conspicuous. The low O3 layer formed over the ocean and lifted by the hurricane circulation and convection, indicates vortex – environment interaction, vertical motion and storm intensity. Upper tropospheric O3 concentrations 10 mm/h, appearing as a protective envelope around the core.

Region: Upper Zambezi catchment and the river flow gauge at Kafue Hook (13.4S, 27.8E), typified by gentle topography and a strong seasonal cycle. Focus: Evaluation of satellite and model estimates of hydro-meteorology conditions using data in the period 1998–2015, to supplement the very limited operational reports coming from the region. Insights: Satellite soil moisture and model run-off track the Kafue Hook gauge with correlation values of 84% and 68%, respectively. Satellite river flow estimates achieve a logarithmic fit to monthly and daily gauge of 92% and 65%, respectively. Discrepancies are related to inadequate (calibration) reporting and to under-estimation of evaporation in the dry season. Statistical analyses of satellite rainfall and model evaporation are used to suggest improvements to hydro-meteorology network coverage in the upper Zambezi. An automated online network of ∼20 weather stations and river flow gauges appears sufficient, given satellite-model ability to interpolate between observations.