Rainfall distribution over Nairobi area
Date
2007Author
Opijah, Franklin J.
Mukabana, Joseph R.
Ng’ang’a, John K.
Type
ArticleLanguage
enMetadata
Show full item recordAbstract
The distribution of rainfall in time and space over Nairobi area is analysed for the 31-year base period
between 1960 and 1990. The high-resolution limited-area numerical model, Geesthacht Simulation Model of
the Atmosphere ( GESIMA) is used to simulate the water substance field over Nairobi City in a case study.
The model is integrated to 24 hours to simulate the diurnal cycle of the moisture budget for a typical day in
the “short rains” season. The model encompasses the real topography, land use/cover characteristics and full
physics. The interaction between large-scale flow and local factors in determining the distribution of categorised
rainfall over the City is assessed. The observed decreasing trend of annual rainfall amounts and frequency
over Nairobi area is attributed to inter-annual variability of large-scale forcing systems. Increasing
trends of heavy rainfall intensities are attributed to anthropogenic forcing through changes in the landscape
on relatively small scales. The effects of small-scale features on the water substance are demonstrated
through numerical simulation: Local features have the capability of modifying the heat budget and airflow patterns
affect the moisture distribution and convection in the entire Nairobi province.
Citation
J. Kenya Meteorol. Soc.,1(1), 3-13 (2007)Publisher
University of Nairobi, Department of Meteorology Meteorology