Crazy floods in Texas
2015-2017
AMS presentation recording (on Harvey) . Jan 2019
Publications:
Yoon, J.-H., S.-Y. Wang, M.-H. Lo, and W.-Y. Wu, 2018: Concurrent increases in wet and dry extremes projected in Texas and combined effects on groundwater. Environmental Research Letters, in press (PDF).
Wang, S.-Y., L. Zhao, J.-H. Yoon, P. Klotzbach, and R. R. Gillies, 2018: Attribution of climate effects on Hurricane Harvey’s extreme rainfall in Texas. Environmental Research Letters, DOI:10.1088/1748-9326/aabb85 (PDF).
Wang, S.-Y., W.-R. Huang, H.-H. Hsu, and R. R. Gillies (2015), Role of the strengthened El Niño teleconnection in the May 2015 floods over the southern Great Plains, Geophys. Res. Lett., 42, doi:10.1002/2015GL065211. (Open Access)
In 2015, a developing El Niño increased late-spring precipitation in the southern Great Plains. Our analyses suggest that this El Niño effect on the southern Great Plains has intensified since 1980. Anthropogenic global warming contributed to the physical processes that caused the persistent precipitation in spring and fall 2015: Warming in the tropical Pacific acted to strengthen the teleconnection toward North America, modification of zonal wave 5 circulation that deepened the stationary trough west of Texas, and enhanced Great Plains low-level southerlies increasing moisture supply from the Gulf of Mexico. Attribution analysis using CMIP5 and the CESM LEP indicated a significant increase in the El Niño-induced precipitation anomalies over Texas and Oklahoma when increases in the anthropogenic greenhouse gases were taken into account.
This connection between ENSO teleconnection and global warming suggests an amplified water cycle extremes not only reflected in widespread flood as in 2015-16, but also can lead to severe drought as was experienced in 2011.
The El Niño teleconnection to the southern Great Plains has amplified; this is evident both in the observation (here in the stream function) and the simulations of CMIP5 & CESM.
The rainy season in Texas-Oklahoma undergoes two peaks: one in late spring and the other in the fall. Both rainy seasons received increased precipitation while the summer dry season was drier. This intensified seasonal transition was documented in a JGR paper.