Precipitation Over Southern Africa: Moisture Sources and Isotopic Composition

Geppert, Marielle; Hartmann, Kai; Kirchner, Ingo; Struck, Ulrich; Riedel, Frank

doi:10.1029/2022jd037005

Cited by 9 publications

(6 citation statements)

References 143 publications

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“…The north-south precipitation gradient also extends from mainland Africa to Madagascar. SA receives the most moisture from continental recycling, while the warm IO (figure 1(c)) contributes the major oceanic moisture source to continental precipitation [45].…”

Section: Resultsmentioning

confidence: 99%

Seasonal variability and predictability of monsoon precipitation in Southern Africa

Horan,

Kucharski,

Ashfaq

2024

Environ. Res. Lett.

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Rainfed agriculture is the mainstay of economies across Southern Africa (SA), where most precipitation is received during the austral summer monsoon. This study aims to further our understanding of monsoon precipitation predictability over SA. We use three natural climate forcings, El Niño–Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and the Indian Ocean Precipitation Dipole (IOPD) – the dominant precipitation variability mode – to construct an empirical model that exhibits significant skill over SA during monsoon in explaining precipitation variability and in forecasting it with a five-month lead. While most explained precipitation variance (50–75%) comes from contemporaneous IOD and IOPD, preconditioning all three forcings is key in predicting monsoon precipitation with a zero to five-month lead. Seasonal forecasting systems accurately represent the interplay of the three forcings but show varying skills in representing their teleconnection over SA. This makes them less effective at predicting monsoon precipitation than the empirical model.

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Section: Resultsmentioning

confidence: 99%

Seasonal variability and predictability of monsoon precipitation in Southern Africa

Horan,

Kucharski,

Ashfaq

2024

Environ. Res. Lett.

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“…(2015), Geppert et al. (2022), and Weldon and Reason (2014). The deserts along the west coast of Namibia and South Africa are related to the combination of the cold Benguela ocean current and the subsidence of the South Atlantic Anticyclone.…”

Section: Resultsmentioning

confidence: 99%

“…In Figure S1 except along the southern coast and western part of South Africa associated with the Benguela current; most of the pr is located over the oceans of the southern part of the study domain. In austral summer (wet season), rainfall expands over almost all land areas with a southerly shifted ITCZ and the northerly winds of the East African Monsoon (Geppert et al, 2022), except for the deserts in the western part. This pronounced seasonal pr cycle with its local features is, for example, in accordance with Engelbrecht et al (2015), Geppert et al (2022), and Weldon and Reason (2014).…”

Section: Simulated Precipitation and 2 M Air Temperature Evaluationmentioning

confidence: 99%

“…In austral summer (wet season), rainfall expands over almost all land areas with a southerly shifted ITCZ and the northerly winds of the East African Monsoon (Geppert et al, 2022), except for the deserts in the western part. This pronounced seasonal pr cycle with its local features is, for example, in accordance with Engelbrecht et al (2015), Geppert et al (2022), and Weldon and Reason (2014). The deserts along the west coast of Namibia and South Africa are related to the combination of the cold Benguela ocean current and the subsidence of the South Atlantic Anticyclone.…”

Section: Simulated Precipitation and 2 M Air Temperature Evaluationmentioning

confidence: 99%

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Convection‐Permitting ICON‐LAM Simulations for Renewable Energy Potential Estimates Over Southern Africa

Chen,

Poll,

Hendricks Franssen

et al. 2024

JGR Atmospheres

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Renewable energy is recognized in Africa as a means for climate change mitigation, but also to provide access to electricity in sub‐Saharan Africa, where three‐quarters of the global population without electricity resides. Reliable and highly resolved renewable energy potential (REP) information is indispensable to support power plants expansion. Existing atmospheric data sets over Africa that are used for REP estimates are often characterized by data gaps, or coarse resolution. With the aim to overcome these challenges, the ICOsahedral Nonhydrostatic (ICON) Numerical Weather Prediction (ICON‐NWP) model in its Limited Area Mode (ICON‐LAM) is implemented and run over southern Africa in a hindcast dynamical downscaling setup at a convection‐permitting 3.3 km horizontal resolution. The simulation time span covers contrasting solar and wind weather years from 2017 to 2019. To assess the suitability of the novel simulations for REP estimates, the simulated hourly 10 m wind speed (sfcWind) and hourly surface solar irradiance (rsds) are extensively evaluated against a large compilation of in situ observations, satellite, and composite data products. ICON‐LAM reproduces the spatial patterns, temporal evolution, the variability, and absolute values of sfcWind sufficiently well, albeit with a slight overestimation and a mean bias (mean error (ME)) of 1.12 m s−1 over land. Likewise the simulated rsds with an ME of 50 W m−2 well resembles the observations. This new ICON simulation data product will be the basis for ensuing REP estimates that will be compared with existing lower resolution data sets.

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“…However, there is a lack of understanding of the attributes of Lesotho snowfall and its associated air mass pathways (Wunderle et al 2016;Grab et al 2017). In southern Africa, studies exploring moisture transport have primarily focused on rainfall (Leketa and Abiye 2020;Rapolaki et al 2020;Geppert et al 2022) and pollution deposition (Rose et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Classifying moisture sources associated with snowfall in the mountains of Lesotho

Marinaki,

Fitchett

2024

J. Mt. Sci.

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An average of eight snowfall events occur each year in the eastern Lesotho Highlands. These snowfall events are typically associated with cut-off low (CoLs) systems and mid-latitude cyclones. However, the moisture sources of the snowfall are unclassified and unclear. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, an air mass back trajectory model, has been used to evaluate moisture source waters locally in southern Africa and internationally in China and Europe. This study uses HYSPLIT to determine the source moisture of snow in Lesotho. A list of all 82 snowfall events in Lesotho spanning 2017 to 2022 was compiled using the Snow Report SA Instagram page, including the date and location of snowfall. A 72-hour back trajectory for each snowfall event was initiated for both Afriski and the whole of Lesotho. This amounts to models of moisture source trajectories for 28 and 82 snowfall days, respectively. These air mass pathways are classified according to their frequency per snowfall event, per month in the snow season, per year and for the full period. From this, associated moisture source regions and dominant air mass trajectories were identified. This study reports that the air mass trajectories associated with Afriski and Lesotho as a whole are very similar. The most common pathway of air mass trajectories transporting snow-bearing moisture to Lesotho was an inland trajectory from the northern regions of southern Africa. This pathway makes up 16.6% of all trajectories reported and is associated with the Angola Low, the Congo Air Boundary and the St. Helena High Pressure.

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Precipitation Over Southern Africa: Moisture Sources and Isotopic Composition

Cited by 9 publications

References 143 publications

Seasonal variability and predictability of monsoon precipitation in Southern Africa

Seasonal variability and predictability of monsoon precipitation in Southern Africa

Convection‐Permitting ICON‐LAM Simulations for Renewable Energy Potential Estimates Over Southern Africa

Classifying moisture sources associated with snowfall in the mountains of Lesotho

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