Seasonal and regional patterns of future temperature extremes: High-resolution dynamic downscaling over a complex terrain

Abstract
The combined impacts of projected/simulated climate change and variability on temperature extremes over a complex topographical terrain along the eastern Mediterranean are assessed in this study. High-resolution dynamical temperature downscaling is conducted for the past (2008) and the near future (until 2050) during eight extreme hot and dry years under two Representative Concentration Pathways (RCP 4.5 and RCP 8.5). The Weather Research and Forecasting (WRF) model is used for the downscaling process with two nested resolutions of 9 and 3 km, forced by the global High-Resolution Atmospheric Model (HiRAM) at a resolution of 25 km. Climate indices resultant from daily simulated temperature illustrate considerable changes in daily maximum summer and minimum winter temperature extremes during the future simulated years in comparison with the historic 2008 selected as reference and control period. While average yearly temperatures increase in both scenarios and most regions as expected, the seasonal variability is forecasted to intensify even more significantly resulting in colder winter and warmer summer conditions. Moreover, the interseasonal variability was most pronounced in the years with the highest averaged temperatures. A notable increase in the annual incidence of hot nights and heat wave events relative to 2008 conditions is also expected. The orographic complexity resulted in significant regional differences, with the most affected regions experiencing more than a doubling of extreme indices during the hottest and driest years of near-future decades. This strong spatial variability highlights the need for high-resolution downscaling.

Citation
El-Samra R, Bou-Zeid E, Bangalath HK, Stenchikov G, El-Fadel M (2018) Seasonal and Regional Patterns of Future Temperature Extremes: High-Resolution Dynamic Downscaling Over a Complex Terrain. Journal of Geophysical Research: Atmospheres 123: 6669–6689. Available: http://dx.doi.org/10.1029/2017jd027500.

Acknowledgements
This study was funded by the United States Agency for International Development through the USAID-NSF PEER initiative (grant AID-OAA-A_I1_00012) in conjunction with support from the U.S. National Science Foundation (grant CBET-1058027). E. Bou-Zeid was also supported by the U.S. National Science Foundation's Sustainability Research Network Cooperative Agreement 1444758. NCAR provided supercomputing resources through projects P36861020 and UPRI0007. The research conducted by the KAUST team was supported by the King Abdullah University of Science and Technology. For computer time, HiRAM simulations used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia.

Publisher
American Geophysical Union (AGU)

Journal
Journal of Geophysical Research: Atmospheres

DOI
10.1029/2017jd027500

Additional Links
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017JD027500

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