SSEC Meetings

Presentation 1630-1700.  Extreme rainfall events are a major prediction challenge with significant socio-economic impacts. If these events are coupled with complex terrain, the ability to accurately predict precipitation accumulation, location, and duration is further complicated. An approach to better understand these heavy rainfall events is by considering the microphysical properties that influence extreme rainfall propagation across the spectrum of high intensity/low duration and low intensity/high duration events. It is hypothesized that warm-rain processes (e.g. collection, accretion) are more dominant in high intensity, short-duration convective events whereas ice processes (e.g. deposition, aggregation) are more dominant in long duration, low intensity stratiform events. Further insight into how these individual processes dominate within the extreme rainfall spectrum, and the role of terrain in modifying or enhancing these processes, could improve future heavy rainfall predictions.

This study utilizes data from an extreme rain event from 1-3 June 2017 located in Taiwan. The extreme rainfall was triggered due to the Mei-Yu front that occurs within the late spring/early summer months near Taiwan. This Mei-Yu rain event lasted three days and brought rain accumulation as high as 1700 mm. The heaviest of rainfalls was in the southern half of Taiwan between the western plains and the Central Mountain Range. Certain areas received up to 1000 mm in rainfall in 24 hours within this region. Another area of interest is in the Taipei Basin. As the MeiYu front entered the island from the North, it remained near-stationary at the coastline producing high intensity rainfall in this populous the region, leading to flooding. It is a particular area of interest due to its location relative to nearby rapidly rising terrain. Each of these areas provide a good example of flat and complex terrain afflicted with heavy rainfall. Data used in this analysis are from operational dual-polarization radars located on the island as well as from rain gauges and soundings. Our current focus is on dual-polarization parameter spaces for inferring microphysical processes across the extreme rainfall spectrum during this case. Future work will focus on altering the terrain within models to test the sensitivities of the microphysical processes. This research will be expanded using data from heavy rainfall events in Taiwan collected during the upcoming 2021 field campaign, Prediction of Rainfall Extremes Campaign In the Pacific (PRECIP).