Littmann et al. (2026) An Empirical Classification of Weather Types and Interrelations with Rainfall and Evapotranspiration in the Southern Western Cape, South Africa

Identification

• Journal: Innovations in landscape research
• Year: 2026
• Date: 2026-01-01
• Authors: Thomas Littmann, Tobias Recke, Maik Veste
• DOI: 10.1007/978-3-032-00993-7_4

Research Groups

• DLC—Dr. Littmann Consulting, Ennepetal, Germany
• CEBra—Center for Energy Technology Brandenburg e.V., Cottbus, Germany
• Department of Molecular Botany, University of Hohenheim, Institute of Biology, Hohenheim, Germany

Short Summary

This study empirically classified five distinct weather types in the Southern Western Cape, South Africa, demonstrating their critical influence on regional rainfall, evapotranspiration, and agricultural water balance. The classification reveals how seasonal changes in near-ground circulation, driven by major pressure centers, dictate local microclimatic processes and agricultural water management needs.

Objective

• To empirically classify weather types in the Southern Western Cape, South Africa, based on daily atmospheric data.
• To analyze the interrelations between these classified weather types and microclimatic processes, specifically rainfall and evapotranspiration, and their impact on the water balance of farmlands.

Study Configuration

• Spatial Scale: Southern Western Cape, South Africa, with specific focus on the Rust en Vrede Farm site.
• Temporal Scale: 13 years (2010–2022), using daily data.

Methodology and Data

• Models used: k-means cluster analysis.
• Data sources: Aerological soundings (for three geopotential heights), reanalysis data, weather station measurements, and FarmImpact measurements.

Main Results

• Five distinct weather types were empirically classified, primarily driven by the seasonal change of near-ground circulation and the strength/position of controlling pressure centers (South Atlantic Anticyclone, mid-latitude, or thermal inland lows).
• In winter, Type 2 is characterized by mid-latitude cyclones, frontal passages, cold air influx, strong wind, and high rainfall (minor frequency). Type 4 represents cyclones further south with frontal systems typically not reaching the Southwestern Cape (more frequent).
• In summer, Type 3 is associated with strong inland thermal lows, a strong South Atlantic Anticyclone, and consequently high wind speeds and temperatures.
• Microclimatic processes, including rainfall, evapotranspiration, and the resulting water balance on farmlands, are largely controlled by these mesoscale atmospheric dynamics.
• Irrigation water consumption and mechanical fruit damage are directly influenced by the frequencies of dry and windy weather types (Types 3 and 1) during the growing season, and rain-bearing types (Types 2, 4, and 5) during the winter half-year, which determine soil, groundwater, and reservoir water storage.

Contributions

• Provides an original empirical classification of weather types specific to the Southern Western Cape, linking synoptic patterns to local microclimatic conditions.
• Quantifies the direct impact of these classified weather types on critical agricultural parameters such as rainfall, evapotranspiration, irrigation requirements, and potential crop damage.
• Offers a valuable framework for understanding regional climate variability and its implications for sustainable agricultural water management in the context of climate change.

Funding

• FarmImpact project, supported by the Federal Ministry of Education and Research (BMBF) and managed by PT-DLR (grant no. FKZ 01LZ1711A-F) as part of the “CLIENT II—International Partnerships for Sustainable Innovations” funding initiative.

Citation

@article{Littmann2026Empirical,
  author = {Littmann, Thomas and Recke, Tobias and Veste, Maik},
  title = {An Empirical Classification of Weather Types and Interrelations with Rainfall and Evapotranspiration in the Southern Western Cape, South Africa},
  journal = {Innovations in landscape research},
  year = {2026},
  doi = {10.1007/978-3-032-00993-7_4},
  url = {https://doi.org/10.1007/978-3-032-00993-7_4}
}