Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana High
Rainfall variability in the sensitive Kalahari semi-desert in Southern Africa, a region of strong climatic gradients, has not been much studied and is poorly understood. Here, anomalies in rainfall totals and moderate and heavy rain day frequencies are examined for both the summer half of the year a...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
|
| Series: | Atmosphere |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4433/16/6/747 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849433844101414912 |
|---|---|
| author | Bohlale Kekana Ross Blamey Chris Reason |
| author_facet | Bohlale Kekana Ross Blamey Chris Reason |
| author_sort | Bohlale Kekana |
| collection | DOAJ |
| description | Rainfall variability in the sensitive Kalahari semi-desert in Southern Africa, a region of strong climatic gradients, has not been much studied and is poorly understood. Here, anomalies in rainfall totals and moderate and heavy rain day frequencies are examined for both the summer half of the year and three bi-monthly seasons using CHIRPS rainfall data and ERA5 reanalysis. Peak rainfall occurs in January–February, with anomalously wet summers marked by a significant increase in the number of rainy days rather than rainfall intensity. Wet summers are linked to La Niña events, cyclonic anomalies over Angola, and a weakened Botswana High, which enhances low-level moisture transport and convergence over the region as well as mid-level uplift. Roughly the reverse patterns are found during anomalously dry summers. On sub-seasonal scales, ENSO and the Botswana High (the Southern Annular Mode) are negatively (positively) significantly correlated with early summer rainfall, while in mid-summer, and for the entire November–April season, only ENSO and the Botswana High are correlated with rainfall amounts. In the late summer, weak negative correlations remain with the Botswana High, but they do not achieve 95% significance. |
| format | Article |
| id | doaj-art-9de96a3a19a14d388bab047be51e3910 |
| institution | Kabale University |
| issn | 2073-4433 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj-art-9de96a3a19a14d388bab047be51e39102025-08-20T03:26:53ZengMDPI AGAtmosphere2073-44332025-06-0116674710.3390/atmos16060747Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana HighBohlale Kekana0Ross Blamey1Chris Reason2Oceanography Department, University of Cape Town, Rondebosch 7700, South AfricaOceanography Department, University of Cape Town, Rondebosch 7700, South AfricaOceanography Department, University of Cape Town, Rondebosch 7700, South AfricaRainfall variability in the sensitive Kalahari semi-desert in Southern Africa, a region of strong climatic gradients, has not been much studied and is poorly understood. Here, anomalies in rainfall totals and moderate and heavy rain day frequencies are examined for both the summer half of the year and three bi-monthly seasons using CHIRPS rainfall data and ERA5 reanalysis. Peak rainfall occurs in January–February, with anomalously wet summers marked by a significant increase in the number of rainy days rather than rainfall intensity. Wet summers are linked to La Niña events, cyclonic anomalies over Angola, and a weakened Botswana High, which enhances low-level moisture transport and convergence over the region as well as mid-level uplift. Roughly the reverse patterns are found during anomalously dry summers. On sub-seasonal scales, ENSO and the Botswana High (the Southern Annular Mode) are negatively (positively) significantly correlated with early summer rainfall, while in mid-summer, and for the entire November–April season, only ENSO and the Botswana High are correlated with rainfall amounts. In the late summer, weak negative correlations remain with the Botswana High, but they do not achieve 95% significance.https://www.mdpi.com/2073-4433/16/6/747rainfall variabilityrain daysKalahari desertENSOSAMmoisture fluxes |
| spellingShingle | Bohlale Kekana Ross Blamey Chris Reason Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana High Atmosphere rainfall variability rain days Kalahari desert ENSO SAM moisture fluxes |
| title | Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana High |
| title_full | Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana High |
| title_fullStr | Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana High |
| title_full_unstemmed | Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana High |
| title_short | Variability in Summer Rainfall and Rain Days over the Southern Kalahari: Influences of ENSO and the Botswana High |
| title_sort | variability in summer rainfall and rain days over the southern kalahari influences of enso and the botswana high |
| topic | rainfall variability rain days Kalahari desert ENSO SAM moisture fluxes |
| url | https://www.mdpi.com/2073-4433/16/6/747 |
| work_keys_str_mv | AT bohlalekekana variabilityinsummerrainfallandraindaysoverthesouthernkalahariinfluencesofensoandthebotswanahigh AT rossblamey variabilityinsummerrainfallandraindaysoverthesouthernkalahariinfluencesofensoandthebotswanahigh AT chrisreason variabilityinsummerrainfallandraindaysoverthesouthernkalahariinfluencesofensoandthebotswanahigh |