GESTAR II Seminar Series with Dr. Courtney Schumacher (Texas A&M University)
Join us for a virtual seminar by Dr. Courtney Schumacher, Professor, Department of Atmospheric Sciences, along with Fadli Nauval, Ryan North, and Erik Nielsen, Texas A&M University. Their talk is titled "The Interacting Weather and Climate Drivers that Produce Extreme Rainfall over the Maritime Continent."
Abstract: This study provides a comprehensive assessment of the multiscale weather and climate drivers and their interactions that govern extreme daily rainfall across the Indonesian Maritime Continent (MC). We first evaluate how the Madden-Julian Oscillation, El Niño–Southern Oscillation, Indian Ocean Dipole, convectively-coupled equatorial waves, and meridional drivers like the Borneo Vortex modulate extreme daily rainfall in cities in the western, central, and eastern MC using IMERG data from 2000-2023. While single drivers account for approximately one-third of extreme wet days, the majority of 95th percentile events are driven by multi-driver combinations, which enhance regional winds and humidity.
Days with extreme daily rainfall also show a distinct diurnal cycle from other rainy days. We demonstrate using GPM radar rain rates and rain type observations that traditional statistical and machine learning techniques struggle in predicting the tail of sub-daily convective and stratiform rain rate distributions over the MC. However, overparameterized neural networks significantly improve the prediction of extreme rain rates, presumably because of their ability to capture the non-linear processes produced by the multiscale and interacting weather and climate drivers.
Finally, we investigate the conditions that lead to the offshore rainfall maxima over the MC, a dominant feature of the region’s hydroclimatology. We employ a novel terrain-relative tracking algorithm over West Sumatra to characterize the properties of individual nocturnal offshore propagating rainfall events using IMERG data from 2016-2018. Propagating systems only occur about a third of the days, but often last 7–10 hours and reach over 250 km from the coast. Event characteristics are shown to be dictated by local drivers, such as the land/sea breeze circulation and gravity waves, but can also vary by Madden-Julian Oscillation and monsoon phases due to changes in synoptic-scale flow. This work emphasizes the need to account for compound environmental conditions to improve extreme rainfall forecasting across the MC.
Biography: Dr. Courtney Schumacher has been a professor in the Department of Atmospheric Sciences at Texas A&M University since 2003. She received her undergraduate degree in Environmental Sciences at the University of Virginia and did her graduate work at the University of Washington. Her primary research revolves around understanding how convective storms become large and long lasting and how to improve predictions of rainfall and extreme rain events. Dr. Schumacher has been heavily involved in field campaigns throughout the tropics, including DYNAMO and GoAmazon, and is an active contributor to NASA’s satellite missions, both the implementation of current missions like PMM and the planning of next missions, including INCUS and the PBL Decadal Survey Incubation program. She was recognized as an AMS Fellow in 2019 and is the holder of the Earl Cook Professorship in Geosciences.
Visit the GESTAR II Seminar Series site for more information on upcoming and previous speakers.