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Villarini, G.
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Villarini, G.
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- PublicationOpen AccessSensitivity of Tropical Cyclone Rainfall to Idealized Global Scale Forcings(2014)
; ; ; ; ; ; ; ; ;Villarini, G.; The University of Iowa ;Lavers, D.; The University of Iowa ;Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Zhao, M.; GFDL ;Wehner, M.; LBNL ;Vecchi, G. A.; GFDL ;Knutson, T. R.; GFDL ;Reed, K.; NCAR; ; ; ; ; ; ; Heavy rainfall and flooding associated with tropical cyclones (TCs) are responsible for a large number of fatalities and economic damage worldwide. Despite their large socio-economic impacts, research into heavy rainfall and flooding associated with TCs has received limited attention to date, and still represents a major challenge. Our capability to adapt to future changes in heavy rainfall and flooding associated with TCs is inextricably linked to and informed by our understanding of the sensitivity of TC rainfall to likely future forcing mechanisms. Here we use a set of idealized high-resolution atmospheric model experiments produced as part of the U.S. CLIVAR Hurricane Working Group activity to examine TC response to idealized global-scale perturbations: the doubling of CO2, uniform 2K increases in global sea surface temperature (SST), and their combined impact. As a preliminary but key step, daily rainfall patterns of composite TCs within climate model outputs are first compared and contrasted to the observational records. To assess similarities and differences across different regions in response to the warming scenarios, analyses are performed at the global and hemispheric scales and in six global TC ocean basins. The results indicate a reduction in TC daily precipitation rates in the doubling CO2 scenario (on the order of 5% globally), and an increase in TC rainfall rates associated with a uniform increase of 2K in SST (both alone and in combination with CO2 doubling; on the order of 10-20% globally).259 325 - PublicationRestrictedHurricanes and climate: the U.S. CLIVAR working group on hurricanes(2015)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Walsh, K. J. E.; University of Melbourne ;Camargo, S. J.; Columbia University ;Vecchi, G. A.; GFDL ;Daloz, A. S.; University of Wisconsin-Madison ;Elsner, J.; Florida State University ;Emanuel, K.; MIT ;Horn, M.; University of Melbourne ;Lim, Y. K.; NASA ;Roberts, M.; Met-Office ;Patricola, C.; Texas A&M University ;Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Sobel, A.; Columbia University ;Strazzo, S.; Florida State University ;Villarini, G.; IOWA University ;Wehner, M.; Lawrence Berkeley National Laboratory, ;Zhao, M.; GFDL ;Kossin, J. P.; NOAA/NCDC ;Larow, T.; Florida State University ;Oouchi, K.; JAMSTEC ;Shubert, S.; NASA ;Wang, H.; NOAA/NCEP ;Bacmeister, J.; NCAR ;Chang, P.; Texas A&M University ;Chauvin, F.; Meteo-France ;Jablonowski, C.; University of Michigan ;Kumar, A.; NOAA ;Murakami, H.; GFDL ;Ose, T.; MRI/JMA ;Reed, K.; NCAR ;Saravanan, R.; Texas A&M University ;Yamada, Y.; JAMSTEC ;Zarzycki, C. M.; University of Michigan ;Vidale, P. L.; University of Reading ;Jonas, J. A.; Columbia Univeristy ;Henderson, N.; Lamont-Doherty Earth Observatory,; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; While a quantitative climate theory of tropical cyclone formation remains elusive, considerable progress has been made recently in our ability to simulate tropical cyclone climatologies and understand the relationship between climate and tropical cyclone formation. Climate models are now able to simulate a realistic rate of global tropical cyclone formation, although simulation of the Atlantic tropical cyclone climatology remains challenging unless horizontal resolutions finer than 50 km are employed. This article summarizes published research from the idealized experiments of the Hurricane Working Group of U.S. CLIVAR (CLImate VARiability and predictability of the ocean-atmosphere system). This work, combined with results from other model simulations, has strengthened relationships between tropical cyclone formation rates and climate variables such as mid-tropospheric vertical velocity, with decreased climatological vertical velocities leading to decreased tropical cyclone formation. Systematic differences are shown between experiments in which only sea surface temperature is increased versus experiments where only atmospheric carbon dioxide is increased, with the carbon dioxide experiments more likely to demonstrate the decrease in tropical cyclone numbers previously shown to be a common response of climate models in a warmer climate. Experiments where the two effects are combined also show decreases in numbers, but these tend to be less for models that demonstrate a strong tropical cyclone response to increased sea surface temperatures. Further experiments are proposed that may improve our understanding of the relationship between climate and tropical cyclone formation, including experiments with two-way interaction between the ocean and the atmosphere and variations in atmospheric aerosols.246 57 - PublicationOpen AccessProjections of Heavy Rainfall over the Central US based on CMIP5 Models(2013)
; ; ; ;Villarini, G.; IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City ;Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Gualdi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; ; The central United States is a region for which observational studies have indicated an increase in heavy rainfall. This study uses projections of daily rainfall from 20 state-of-the-art global climate models and one scenario (RCP 8.5) to examine projected changes in extreme rainfall. Analyses are performed focusing on trends in the 90th and 99th percentiles of the daily rainfall distributions for two periods (2006-2045 and 2046-2085). The results of this study indicate a large increase in extreme rainfall in particular over the northern part of the study region, with a much less clear signal over the Great Plains and the states along the Gulf of Mexico.169 102 - PublicationOpen AccessIntense precipitation events associated with landfalling tropical cyclones in response to a warmer climate and increased CO2(2014)
; ; ; ; ; ; ; ;Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Gualdi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Villarini, G.; University of IOWA ;Vecchi, G. A.; GFDL ;Zhao, M.; GFDL ;Walsh, K.; University of Melbourne ;Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; ; ; ; ; ; In this work the authors investigate possible changes in the intensity of rainfall events associated 28 with tropical cyclones (TCs) under idealized forcing scenarios, including a uniformly warmer climate, with a special focus on landfalling storms. A new set of experiments designed within the U.S. CLIVAR Hurricane Working Group allows disentangling the relative role of changes in atmospheric carbon dioxide from that played by sea surface temperature (SST) in changing the amount of precipitation associated with TCs in a warmer world. Compared to the present day simulation, we found an increase in TC precipitation under the scenarios involving SST increases. On the other hand, in a CO2 doubling-only scenario, the changes in TC rainfall are small and we found that, on average, TC rainfall tends to decrease compared to the present day climate. The results of this study highlight the contribution of landfalling TCs to the projected increase in the precipitation changes affecting the tropical coastal regions.248 231