Table 1.

Non‐Exhaustive Overview of Moisture Recycling Studies Over the African Continent

Reference	Area	Main findings	Methods/models	Input data source
Savenije (1995)	Sahel	Moisture recycling in the Sahel account for 90% of the rainfall Irrigation during the dry season does not necessarily lead to increased precipitation due to low atmospheric vapor	Simple linear analytical model based on Budyko (1974)	Rainfall gauges and runoff observations (field‐based)
Gong and Eltahir (1996)	West Africa (5°N–15°N, 10°W–15°E)	Precipitation in West Africa derives for 23%, 27%, and 17% on evaporation from the Atlantic Ocean, West Africa and Central Africa, respectively Moisture supply from Central Africa is limited by the westerly monsoonal circulation	Mass balance based on Budyko (1974)	ERA‐40, 2.5°, daily, 1985–1995
Mohamed et al. (2005)	Nile Basin	Mean annual local moisture recycling of 11%	Regional Atmospheric Climate MOdel (RACMO), applying Budyko framework, run for 35.96°N–12°S and 10°E−54.44°E, 0.44°	RCM initialized with ERA‐40, 2.5°, 1995–2000Vegetation cover from GLCC GlobalLand Coverage CharacteristicsDischarge data (gauged measurements at 11 stations)Precipitation from ground stations; GPCC, 1°, monthly; FEWS, 0.1°
Los et al. (2006)	Sahel	Vegetation‐rainfall feedback explains up to 30% of the rainfall variability between 15° and 20°N	Statistical Vegetation Index Simulation (SVIS)	NDVI from AVHRR, 0.5°, monthly, 1982–1999Precipitation and temperature from CRU, 0.5°, monthly, 1901–2000
Van der Ent et al. (2010)	African continent	West‐Africa is a major (precipitation) sink of continental evaporation Indian Ocean provides moisture to East and Central Africa, which in its turn provides moisture to West Africa Total precipitation from continental (terrestrial) origin over Africa = 49%	Water accounting model	ERA‐Interim, 1.5°, 6 hourly, 1998–2008
Pokam et al. (2012)	Equatorial Central Africa (5°N–5°S and 12.5°E–30°E)	Seasonal variability in moisture convergence determined by African Easterly Jet location and Atlantic Ocean Mean annual recycling ratio of 0.38 Low annual cycle/variability of recycling ratio	2D bulk recycling model based on (Burde et al. (2006)	National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, 1.9° and 2.5°, (monthly., at 1.9° × 1.9° and 2.5° × 2.5°)
Keys et al. (2014)	Western Sahel	Variation in Sahelian E most important to explain variance of precipitation 50.1% of the precipitation in the “core precipitation shed” derives from the land surface	Eulerian Water Accounting Model 2 Layers (WAM‐2Layers, v2.3.01),	ERA‐Interim, 1.5° and MERRA, 1.0° × 1.25°, 1979–2013
Salih et al. (2015)	Sahelian Sudan	ITCZ is the main source of moisture During July and August, the ITCZ brings in half of the precipitation Despite being relatively dry, trade winds from the Arabian Peninsula are responsible for almost 30% of the precipitation	FLEXPART v6.2	ERA‐Interim, 1.5° and 2°, 3/6 hourly, 1998–2008
Miralles et al. (2016)	East and West Sudanian Savanna, Serengeti, Kalahari Desert	East Sudanian Savanna receives almost all P from terrestrial E Recycling ratio Kalahari Desert during growing season 34% Local recycling ratios increase during dry years (intensification of dry conditions)	FLEXPART v9.0	ERA‐Interim, Evaporation from GLEAMand OAFLUXVegetation Optical Depth (VOD), all data regridded to 0.25° with monthly time steps
Oguntunde et al. (2016)	Niger Basin	Local recycling between June and September amounts 21%	Regional Climate Model (RegCM3) over 1981–2000	ERA‐InterimPrecipitation and temperature from CRU TS 2.1 (0.5°, monthly) River discharge from gauging stations
Dyer et al. (2017)	Congo Basin (10°S–5°N and 15°E−30°E)	Local E contribution varies between 24% and 38% throughout the year	Water tagging capability in NCAR Community Earth System Model (CESM v1.2), run at 1.9° × 2.5° (30 vertical levels)	CRU, GPCP, ERA‐Interim, and GPCC precipitation data sets
Sorí et al. (2017)	Congo Basin	The Congo Basin provides over 50% of the total atmospheric moisture for precipitation High oceanic E events are not directly linked to increased P over the basin Dry/wet years are associated with lower/higher local moisture contribution	FLEXPART v9.0	Precipitation from CRU TS v3.23, 0.5°Runoff from GRDCEvaporation from GLEAM v2 and OAFLUXERA‐Interim, 1°, 6 hourly
Yu et al. (2017)	Sahel	Oceanic forcing (i.e., SST) dominates precipitation variability (22% annual mean), except during post‐monsoon period (SON) Annual mean terrestrial forcing of 8%, with 18% in SON	A multivariate, lagged Generalized Equilibrium Feedback Assessment (GEFA)	Various land and ocean variables, see Yu et al. (2017) supplementary material for full overview
Keys and Wang‐Erlandsson (2018)	Niger	41% of annual precipitation derives from the ocean 9% derives from Niger itself, mostly from the South of the country	WAM‐2layers	ERA‐Interim, 1.5°, 3/6 hourly
Wang‐Erlandsson et al. (2018)	Congo Basin	Half of the streamflow in the Congo river is depending on terrestrial moisture recycling	STEAM and WAM‐2Layers	Meteorological data with ERA‐Interim, 1.5°, 3/6 hourly, 1995–2014Land Cover data with Ramankutty potential land‐cover, IGBP (MCD1C1), MIRCA2000 v1.1Precipitation from MSWEP v1, 0.25° regridded to 1.5°Runoff data from GRDC, 0.5° regridded to 1.5°
Notaro et al. (2019)	Sahel, Greater Horn of Africa, WAM‐region, Congo basin	Land–atmosphere feedbacks are most prominent in semi‐arid regions Forcing impact of soil moisture and vegetation is comparable of oceanic forcing for the whole region	A multivariate Stepwise Generalized Equilibrium Feedback Assessment (SGEFA)	Various land surface variables, see Table 1 in Notaro et al. (2019) for full overview
Tuinenburg et al. (2020)	Congo basin	Evaporation recycling of 60% Precipitation recycling of 47%	UTrack, analysis at 0.5°, monthly	ERA5, 0.25°, hourly, 2008–2017
Worden et al. (2021)	Congo basin	83% of free tropospheric moisture comes from terrestrial E in February (first rain peak) During the second rain peak (September–October), only 31% derives from terrestrial E	Statistical model based on satellite observations of deuterium content in water vapor	Deuterium content from NASA Tropospheric Emission Spectrometer; SIF from GOME‐2 V26 740 nm data productsPrecipitation from TRMM, 0.25°.E from MODIS and ERA5, 0.25°, daily