Options
Walsh, K. J. E.
Loading...
5 results
Now showing 1 - 5 of 5
- 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 - PublicationRestrictedTracking Scheme Dependence of Simulated Tropical Cyclone Response to Idealized Climate Simulations(2014)
; ; ; ; ; ; ; ; ; ; ; ; ;Horn, M.; Melbourne University ;Walsh, K.; Melbourne University ;Zhao, M.; GFDL ;Camargo, S.; Columbia University NY ;Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Murakami, H.; GFDL ;Ballinger, A.; Princeton University ;Wang, H.; NOAA ;Kumar, A.; NOAA ;Shaewitz, D.; Columbia University NY ;Jonas, J. A.; NASA ;Oouchi, K.; IPRC/MRI; ; ; ; ; ; ; ; ; ; ; Future tropical cyclone activity is a topic of great scientific and societal interest. In the absence of a climate theory of tropical cyclogenesis, general circulation models are the primary tool available for investigating the issue. However, the identification of tropical cyclones in model data at moderate resolution is complex, and numerous schemes have been developed for their detection. We here examine the influence of different tracking schemes on detected tropical cyclone activity and responses in the Hurricane Working Group experiments. These are idealized atmospheric general circulation model experiments aimed at determining and distinguishing the effects of increased sea-surface temperature and other increased CO2 effects on tropical cyclone activity. We apply two tracking schemes to these data and also analyze the tracks provided by each modelling group. Our results indicate moderate agreement between the different tracking methods, with some models and experiments showing better agreement across schemes than others. When comparing responses between experiments, we find that much of the disagreement between schemes is due to differences in duration, wind speed, and formation-latitude thresholds. After homogenisation in these thresholds, agreement between different tracking methods is improved. However, much disagreement remains, accountable for by more fundamental differences between the tracking schemes. Our results indicate that sensitivity testing and selection of objective thresholds are the key factors in obtaining meaningful, reproducible results when tracking tropical cyclones in climate model data at these resolutions, but that more fundamental differences between tracking methods can also have a significant impact on the responses in activity detected.209 45 - 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.248 234 - PublicationRestrictedResolution dependence of tropical cyclone formation in CMIP3 and finer resolution models(2013)
; ; ; ;Walsh, K.; School of Earth Science Univ. of Melbourne ;Lavander, S.; CSIRO ;Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; ; Detection of tropical lows is performed in a suite of climate model simulations using objectively-determined detection thresholds that are resolution-dependent. It is found that there is some relationship between model resolution and tropical cyclone formation rate even after the resolution-dependent tropical cyclone detection threshold is applied. The relationship is investigated between model-simulated tropical cyclone formation and a climate-based tropical cyclone Genesis Potential Index (GPI). It is found that coar- ser-resolution models simulate the GPI better than they simulate formation of tropical cyclones directly. As a result, there appears to be little relationship from model to model between model GPI and the directly-simulated cyclone formation rate. Statistical analysis of the results shows that the main advantage of increasing model resolution is to give a considerably better pattern of cyclone formation. Finer resolution models also simulate a slightly better pattern of GPI, and for these models there is some relationship between the pattern of GPI simulated by each model and that model’s pattern of simulated tropical cyclone formation.105 20 - PublicationRestrictedThe Tropical Cyclone Climate Model Intercomparison Project(2010)
; ; ; ; ; ;Walsh, K.; School of Earth Sciences, University of Melbourne, Australia ;Lavander, S.; School of Earth Sciences, University of Melbourne, Australia ;Murakami, H.; Meteorological Research Institute, Tsukuba, Ibaraki, Japan ;Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Caron, L. P.; CRCMD Network, UQAM, Montreal, Canada; ; ; ; ; ; Elsner, J. B.In this chapter, a review is given of progress to date on an intercomparison project designed to compare and evaluate the ability of climate models to generate tropical cyclones, the Tropical Cyclone climate Model Intercomparison Project(TC-MIP). Like other intercomparison projects, this project aims to evaluate climate models using common metrics in order to make suggestions regarding future development of such models.99 21