Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity
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Material Information

Title:
Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity CMIP3 and CMIP5 Model-based Scenarios
Creator:
Thomas Knutson
Joseph J. Sirutis
Gabriel A. Vecchi
Steven Garner
Ming Zhao
Hyeong-Seong Kim
Morris Bender
Robert E. Tuleya
Isaac M. Held
Gabriele Villarini
Publisher:
American Meteorological Society
Publication Date:
Language:
English

Notes

Abstract:
Twenty-first century projections of Atlantic climate change are downscaled to explore the robustness of potential changes in hurricane activity. Multi-model ensembles using the CMIP3/A1B (Late 21st century) and CMIP5/RCP4.5 (Early and Late 21st 23 century) scenarios are examined. Ten individual CMIP3 models are downscaled to assess the spread of results among the CMIP3 (but not the CMIP5) models. Downscaling simulations are compared for 18-km regional and 50-km grid global models. Storm cases from the regional model are further downscaled into the GFDL hurricane model (9 km inner-grid spacing, with ocean coupling) to simulate intense hurricanes at finer resolution. A significant reduction in tropical storm frequency is projected for the CMIP3 (-27%), CMIP5-Early (-20%) and CMIP5-Late (-23%) ensembles, and for five of ten individual CMIP3 models. Lifetime-maximum hurricane intensity increases significantly in the high-resolution experiments--by 4 to 6% for CMIP3 and CMIP5 ensembles. A significant increase (+87%) in the frequency of very intense (Category 4-5) hurricanes (winds >= 59 m s-133 ) is projected using CMIP3, but smaller, only marginally significant increases are projected (+45% and +39%) for the CMIP5-Early and CMIP5-Late scenarios. Hurricane rainfall rates increase robustly for the CMIP3 and CMIP5 scenarios. For the late 21st century, this increase amounts to +20 to +30% in the model hurricane’s inner core, with a smaller increase (~10%) for averaging radii of 200 km or larger. The fractional increase in precipitation at large radii (200-400 km) approximates that expected from environmental water vapor content scaling, while increases for the inner core exceed this level.

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Source Institution:
Florida International University
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