The first climate meeting of this fall will feature two speakers:
Dr. Catherine Pomposi will give a 30 minute talk entitled “Rethinking the role of El Niño on precipitation in subtropical Africa.” The abstract reads: “The El Niño Southern Oscillation (ENSO) is a leading mode of interannual precipitation variability throughout the semi-arid tropics, which includes parts of West and Southern Africa. Interannual precipitation variability linked to ENSO can have drastic impacts on agricultural systems and food resources. This highlights a need for increased information regarding ENSO’s links to sub-seasonal to seasonal precipitation variations in such precarious regions. The present work describes two case studies on recent precipitation variability during warm ENSO events (El Niño) for the West African Monsoon season (June-September) and the austral summer rainy season (December-February) in Southern Africa. Using a blending of observational and model data, it is found that for West Africa, recent El Niño years have resulted in wetter than normal conditions when the sub-tropical Atlantic plays a modulating role and increases moisture supply to the region. For Southern Africa, it is found that the probability distribution of precipitation varies according to the strength of El Niño events. Strong El Niño events show a much clearer tendency for drying than moderate or weak events, which have smaller absolute magnitude anomalies and larger spatial heterogeneity in the precipitation response. I will also discuss potential avenues for future research and how the results of this study could impact decision-making in the regions.”
Catherine Pomposi is currently a postdoctoral research scientist within the Postdocs Applying Climate Expertise (PACE) fellowship program sponsored by UCAR/NOAA. Dr. Pomposi completed her Ph.D. at Columbia University where she studied the mechanisms of oceanic forced Sahel precipitation variability on timescales ranging from sub-seasonal to decadal. Her research interests are broadly focused on regional climate variability, predictability, and change, and the application of climate information in service of societal needs.
Tessa Montini will give a 15 minute talk entitled “Assessment of Uncertainties in Recent Changes in the South American Low-Level Jet based on Various Reanalyses.” The abstract for her talk is as follows: “The South American low-level jet (SALLJ) is one of the key components of the South American Monsoon System. The SALLJ transports large amounts of moisture to the subtropics, influencing the development of deep convection and heavy precipitation over southeastern South America. Previous studies have analyzed the jet using reanalysis data due to the lack of available upper-air observations over this region. The purpose of the current study is to quantify uncertainties in the climatology, variability, and changes in the SALLJ based on various reanalyses for the period 1979–2015. This is important because there are significant differences among reanalysis datasets due to variations in their data quality control, data assimilation systems, and model physics. The datasets used in this analysis are: (1) CFSR, (2) ERA-Interim, (3) JRA-55, and (4) MERRA-2. Finally, significant changes in the SALLJ are discussed in relation to substantial warming over South America in recent decades and changes in the monsoon.”
Tessa Montini is currently a PhD candidate in geography.