The role of land-atmosphere and aerosol interactions on meso-scale convective weather systems across West Africa
Abstract
This dissertation investigates the modulating effects of land-atmosphere and
aerosol interactions on meso-scale convective systems across the sub-Saharan West
Africa region, and aims at providing a value-added contribution towards better
understanding of the controlling mechanisms for these interactions, in order to
improve predictability of the highly frequent, high-impact meso-scale convective
systems. It is very well known that aerosols alter the surface energy budget resulting
into complex and multi-scale interactions between the land-atmosphere and mesoscale
convective systems, which are yet to be fully understood. In this study, we used
a highly proven successful cognitive recognition artificial neural network intelligence
problem solving tool - Self-Organizing Maps (SOM) in investigating the modulating
effects of aerosol-land-atmosphere interactions for enhancing the predictability of
meso-scale convective systems. The SOM method is not yet commonly used by
climate scientists for solving climate research problems. For the first time in this
research - at least to the best of our knowledge - we used the SOM method to solve
climate research problems over Africa. Our results show very strong seasonal influence in determining the dominant controlling variable (e.g. soil moisture,
aerosols) on the interactions between atmospheric aerosols, meso-scale convective
systems and land-surface properties across the study region. It was also found that
these controlling variables are generally very significant in modulating atmospheric
interactions across the region during the monsoon (wet) seasons than during the nonmonsoon
(dry) seasons. Furthermore, results showed that even though there is
noticeable control by aerosols on the interactions between land-atmosphere and
meso-scale convective systems, available surface soil moisture exerts the most
dominant control across the region especially during the active convective period
(monsoon season) of the year. Results further showed that soil moisture has the
potential to control the convective available potential energy (CAPE) up to about
79% during the monsoon season and up to about 67% during the non-monsoon
seasons, while aerosols can control CAPE up to about 67% during monsoon and up
to about 23% during the non-monsoon season.
Table of Contents
Introduction -- Literature review -- The study area -- Data analysis and research methodology -- Results and discussion -- Conclusion and recommendations
Degree
Ph.D.