Alexander Lemburg received award of American Meteorological Society for outstanding presentation

Photo © MPI-M, B. Diallo

The American Meteorological Society awarded the “Outstanding Student Oral Presentation” to Alexander Lemburg. He is a PhD candidate in the department “The Land in the Earth System” at the Max Planck Institute for Meteorology (MPI-M) and received the award for his presentation “Sahel Rainfall—Tropical Easterly Jet Interaction on Intraseasonal Time-Scales with a Focus on the Role of Jet-Induced Upper-Level Divergence for Mesoscale Convective Systems” during the 32nd Conference on Climate Variability and Change in January 2019. The award recognizes outstanding presentations and posters by PhD candidates and postdocs and is endowed with a prize of $125.

In his presentation in Phoenix Alexander Lemburg showed that the variability of the Tropical Easterly Jet (TEJ) over West Africa has no substantial influence on precipitation in the Sahel on short time scales. An active role of the TEJ in precipitation development was discussed controversially in the literature before.

The TEJ is a band of high wind speeds in the upper troposphere that extends from the Indian monsoon system to West Africa during the summer months and is a typical feature of the West African monsoon. Previous studies showed that the TEJ intensity over West Africa is strongly correlated with Sahel rainfall on decadal and interannual time scales. It has also been suggested that the location and intensity of the TEJ determines the large-scale convergence and divergence in the upper troposphere over West Africa and thus possibly also the distribution of precipitation. Particularly on shorter time scales, substantially increased divergence may occur in the vicinity of regional jet maxima, so-called jet streaks, which, according to a recently published case study, could promote the initiation and, in particular, organization of deep convection. These previous studies, which attribute a possible active role in precipitation development over West Africa to the TEJ, motivated Alexander Lemburg, Jürgen Bader and Martin Claußen to revisit the relationship  between TEJ over West Africa and Sahel precipitation—on synoptic to intraseasonal time scales. With the help of comprehensive statistical analyses of spatially and temporally high-resolution observation data and reanalysis models, Lemburg et al. were able to show that the variability of the TEJ within a monsoon season is more a consequence of precipitation variability than vice versa. Furthermore, there was no evidence that upper-level divergence anomalies associated with the TEJ play a supportive role in the initiation and organization of mesoscale convective systems.

The research results presented at the conference, which are part of Alexander Lemburg´s doctoral thesis, were also recently published in the journal “Monthly Weather Review” of the American Meteorological Society. The article, currently still in a pre-release version, can be found at the following link: journals.ametsoc.org/doi/abs/10.1175/MWR-D-18-0254.1


Further information:
Abstract of Alexander Lemburg´s presentation
Website American Meteorological Society

 

Contact:
Alexander Lemburg
Max Planck Institute for Meteorology
Phone: +49 40 41173 254
Email: alexander.lemburg@we dont want spammpimet.mpg.de