Juliane Schwendike

Currently, I am applying a new technique to three-dimensional reanalysis data to describe local Hadley and local Walker circulations, and how these circulations change under the influence of ENSO. A significant advantage of our method is that it allows us to compute averages over limited domains, and hence investigate regional Hadley and Walker circulations, for instance, over the Maritime Continent and the Pacific. Additionally, I calculate and analyse linear trends for the local Hadley and local Walker circulations during the last 30 years.

My PhD at Karlsruher Institut fuer Technologie, Germany, investigated how convection over West Africa and over the Atlantic within the same African easterly wave (AEW) differs, and how these differences aid the tropical cyclogenesis. These mesoscale convective systems (MCSs) have a horizontal extent of several hundreds of kilometres and they account for about 80% of the annual rainfall in West Africa. I used the COSMO (COnsortium for Small-scale MOdelling) model, which is the operational forecast model of the German Weather Forecast Service (DWD), to simulate the AEW out of which Hurricane Helene (2006) developed, as well as the embedded MCSs. I computed and analysed potential temperature, relative humidity and momentum budgets to investigate the similarities and differences between the convection over land and water. To gain a better understanding of the dynamics of the convective systems, I also analysed relative and potential vorticity budgets.

During the period under investigation significant amounts of mineral dust were present. I used the model system COSMO-ART (Aerosols and Reactive Trace gases), which includes the emission and transport of mineral dust, to investigate the pathways along which the mineral dust was transported, and how it reached the developing tropical depression that became Hurricane Helene.