EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Future projections in tropical cyclone activity over multiple CORDEX domains from RegCM4 CORDEX-CORE simulations

Abraham Torres1, Russell Glazer1, Erika Coppola1, Xuejie Gao2, Kevin Hodges3, Sushant Das1, and Moetasim Ashfaq4
Abraham Torres et al.
  • 1Earth System Physics, The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy (
  • 2Climate Change Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
  • 3Department of Meteorology, University of Reading, Reading, United Kingdom
  • 4Computer Science and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA

Under the Coordinated Regional Downscaling Experiment (CORDEX) initiative, simulations of tropical cyclones were performed using the latest version of the International Centre for Theoretical Physics (ICTP) Regional Climate Model 4 (RegCM4) at a spatial resolution of 25 km over four domains (Australasia, Central America, Western Pacific and South Asia). These simulations cover the 130-year period, 1970-2099, for two Representative Concentration Pathways, 2.6 (RCP2.6) and 8.5 (RCP8.5) emission scenarios and were driven by three General Circulation Models (GCMs) from phase 5 of the Coupled Model Inter-comparison Project (CMIP5). In these simulations, the potential changes in TC activity for future climate conditions over five areas of tropical cyclone formation (North Indian Ocean, the Northwest Pacific, North Atlantic, Australasia and Eastern Pacific) are investigated, using an objective algorithm to identify and track them. The RegCM4 simulations driven by GCMs are evaluated for the period of 1995–2014 by comparing them with the observed tropical cyclone data from the International Best Track Archive for Climate Stewardship (IBTrACS); then the changes in two future periods (2041-2016 and 2080–2099), relative to the baseline period (1995–2014), are analyzed for RegCM4 simulations driven by GCMs. Preliminary results show that RegCM4 simulations driven by GCMs are capable of most of the features of the observed tropical cyclone climatology, and the future projections show an increase in the number of tropical cyclones over the North Indian Ocean, the Northwest Pacific and Eastern Pacific regions. These changes are consistent with an increase in mid-tropospheric relative humidity. On the other hand, the North Atlantic and Australasia regions show a decrease in tropical cyclone frequency, mostly associated with an increase in wind shear. We also find a consistent increase in the future storm rainfall rate and the frequency of the most intense tropical cyclones over almost all the domains. Our study shows robust and statistically significant responses, often, but not always, in line with previous studies. This implies that a robust assessment of tropical cyclone changes requires analyses of ensembles of simulations with high-resolution models capable of representing the response of different characteristics of different key atmospheric factors.

How to cite: Torres, A., Glazer, R., Coppola, E., Gao, X., Hodges, K., Das, S., and Ashfaq, M.: Future projections in tropical cyclone activity over multiple CORDEX domains from RegCM4 CORDEX-CORE simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8800,, 2020

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Presentation version 1 – uploaded on 03 May 2020
  • CC1: Comment on EGU2020-8800, Steven C. Chan, 04 May 2020

    How important are the LBCs to your results? Do your control climate and projections results show large differences between different driving models?

    Thank you

    • AC1: Reply to CC1, Abraham Torres, 04 May 2020

      Steven C. Chan, we found some differences between different driving models. Some are better in specific basins but also we found that the RegCM simulations driven by MPI-ESM-MR performs better in reproducing the TC activity over all the domains. When we assess the future changes in TC activity, we found a consistent response between the different RegCM simulations, particularly in the frequency of the most intense tropical cyclones and TC rainfall. Thanks for your interest. Let me know if you have any more questions!

      • CC2: Reply to AC1, Steven C. Chan, 04 May 2020

        Thank you for the reply.

        I guess max intensity and precipitation are probably heavily controlled by RegCM model physics. I guess what I was thinking under what situations the LBCs controlled the changes and biases, and what situations the downscaling model controlled the changes and biases.

        • AC2: Reply to CC2, Abraham Torres, 04 May 2020

          That's a difficult question, but I will give you an example, the RegCM driven by the HadGEM2-ES works good over the Eastern Pacific and South Pacific. But it doesn't over the North Atlantic. The GCM produces few TCs and the RegCM4 driven by HadGEM2-ES increases the number of TCs but the bias remains. Checking the GCM we found that the model has a strong vertical wind shear over the Caribbean. Under this situation I think the LBCs controlled the bias. 

          On the other hand, the GCMs produce cool SST in the Atlantic but we didn't find a consistent bias related. Here I think the downscaling model controlled the biases.

          Please, let me know if you have any more questions