TITLE:
Diurnal Cycle of Rainfall and Convective Properties over West and Central Africa
AUTHORS:
Richard Ayodeji Balogun, Elijah Adesanya Adefisan, Zechariah Debo Adeyewa, Emmanuel Chilekwu Okogbue, Ademola Akinbobola
KEYWORDS:
Convective, Diurnal Cycle, Flashcount, System Sizes
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.12 No.1,
January
4,
2022
ABSTRACT: The need to investigate diurnal weather cycles in West Africa originates
from the fact that complex interactions often result between mesoscale and
synoptic weather processes. This study investigates diurnal cycles of rainfall
and convective properties using six (6) hour interval data from the ERA-Interim
and derived products from the Tropical Rainfall Measurement Mission (TRMM).
Results showed that the land-ocean warming contrast is more strongly sensitive to the seasonal cycle, being very weak during
March-May (MAM) but clearly spelled out during June-September (JJAS). Dipoles of wind convergence/divergence and wet/dry precipitation, between CASS and Nigeria
Savannah zones, were identified in the morning and evening hours of MAM, whereas
distinct night and day anomalies, same location in CASS, were found to be
consistent during the JJAS season. The locations of flash count and system
sizes agree with the climatology of convective properties, that morning and
day-time hours are dominated by stratiform precipitation and small system
sizes. Most results clearly showed that the eastern locations of Sudano and
Sahel are consistently dry because rainfall and precipitation features are
predominantly few. Very unique results about the dipole of wind and
precipitation between two zones and the unusual dry zones of Sudan and Sahel
have been found. Results presented had shown the importance of diurnal
variation in understanding precipitation, flash count, system sizes patterns at
diurnal scales, and understanding land-ocean contrast, precipitation and wind
field anomaly at diurnal scales.