Quantification of Air Pollution in Kigali City and Its Environmental and Socio-Economic Impact in Rwanda
Year: 2015
Type: article
Abstract: Reproducing the behavior of the mean variables that control the nocturnal atmospheric flow under very stable conditions is a very difficult task for atmospheric models. To understand the role of the surface scheme, turbulence scheme and radiation scheme on the performance of a single column model, its predictions are compared to observations collected at a very stable site located in deforested region in Amazon. The surface scheme takes on consideration the rapid changes in the surface energy budget caused by the presence of a vegetated layer over the soil. The turbulence scheme uses four different formulations for the mixing length. Two of them allow the existence of turbulence over the critical Richardson number, while the other two restrict dramatically the turbulence activity in those situations. The radiative scheme considers a clear sky condition, and evaluates the radiative flux divergence between 3 levels within the vertical domain: near the surface, at the domain top, and at the middle point between them. The predictions of all mixing length formulations are very similar to the observed data near the surface, indicating that in this region the surface plays a crucial role. At upper levels the most turbulent formulations lead to better results. This is a consequence of atmospheric decoupling when the turbulence is completely suppressed, which leads to colder results near the surface and warmer results aloft. The radiative scheme reproduces quite well the temperature decay above the boundary layer for all cases, in spite of its simplicity. On the other hand, the comparison between modeled and observed humidity profiles shows that it is necessary to improve the model by including a more complete scheme for humidity and by adding a advection scheme to it.
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: diamond
OpenAlex ID: W376619266