Abstract
Relatively little is known about the urban climate processes of the fastest growing cities in the world today. Described in this paper are urban–rural and intra‐urban variations in air temperature and humidity in one of these cities; Ouagadougou, Burkina Faso. Measurements were collected from car traverses and fixed site measurements during two field studies. The aim of the study was to determine the influence of land use on the urban climate in this hot‐dry region, with a focus on the role of vegetation and of a large centrally located reservoir.
Analyses of results show that vegetation is the most important factor in the nocturnal urban climate in Ouagadougou, while effects of built up and paved areas are limited. Average urban–rural temperature differences demonstrate that while the evening urban heat island (UHI) reached only 1.9 °C, the cool island in a densely vegetated area was 5.0 °C cooler than the dry rural reference. Temperature differences of the same magnitude persisted throughout the night between vegetated and non‐vegetated areas, regardless of urban or rural setting. Cooling from the open water of the reservoir was the most important parameter during daytime, while during evenings and nights, direct effects of the open water of the reservoir are very limited, and the availability of water, allowing enhanced vegetation cover, is of much greater importance compared to the water itself.
The results presented here show that the urban land cover, together with climatic region, can create significant differences in the physical properties driving the urban climate in a dry‐tropical city compared to those commonly found in temperate cities. Copyright © 2010 Royal Meteorological Society