Back to Search Start Over

Structure, modulation and impacts of southeastern Africa's diurnal convection.

Authors :
Jury, Mark R.
Source :
Theoretical & Applied Climatology. Jun2024, Vol. 155 Issue 6, p4851-4862. 12p.
Publication Year :
2024

Abstract

This study explores the structure, modulation, and impacts of the mean diurnal climate across southeast Africa using high-resolution hourly reanalysis and satellite rainfall. This research was motivated by upward trends in diurnal temperature range and vegetation index over the Drakensberg escarpment. Statistical analysis identified a land-sea rainfall dipole pattern associated with diurnal airflows. Point-to-field regressions (Oct–Mar 2000–2023) found that sea breeze-driven convection is underpinned by 'col' airflow between adjacent sub-tropical low-pressure cells (30°S, 20°E/22°S, 37°E) and a weak mid-latitude anticyclone (40°S, 10°E). Diurnal residual and case study analysis demonstrate an ~ 6-m/s sea breeze penetrating ~ 200 km inland during the day, as part of an over-turning zonal circulation. Land > sea rainfall during summer is initiated by temperature gradients ∂T/∂x ~ 5 °C at 29°S, 31°E and convergence in the afternoon ∂U/∂x ~ − 4 × 10−5 s−1. Further inland (29°S, 26°E) a 1007-hPa thermal low and counter-clockwise rotating airflows interact with the incoming sea breeze. Together these contribute to evening rainfall ~ 30 mm over the Drakensberg escarpment. The drivers of diurnal rainfall show little response to global climate variability, and help sustain water resources during multi-year dry spells over southeastern Africa. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0177798X
Volume :
155
Issue :
6
Database :
Academic Search Index
Journal :
Theoretical & Applied Climatology
Publication Type :
Academic Journal
Accession number :
178459689
Full Text :
https://doi.org/10.1007/s00704-024-04885-y