Idealized simulations of tropical cyclones with thermodynamic conditions under reanalysis and CMIP5 scenarios

The idealized Weather Research and Forecasting (WRF) simulations are conducted to investigate tropical cyclone (TC) size and intensity over the Western North Pacific (WNP) over the past decades, as represented by National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) R-1, European Center for Medium range Weather Forecasting (ECMWF) twentieth century (ERA20C) reanalysis, and National Oceanic and Atmospheric Administration Cooperative Institute for Research in Environmental Sciences 20th Century (CIRES20) Reanalysis V2 data, and under a future climate, as predicted by the Coupled Model Intercomparison Project Phase 5 (CMIP5). Firstly, sensitivity experiments with varying environmental thermodynamic forcing are conducted to examine how thermodynamic conditions affect TC size and intensity. Secondly, distributions of thermodynamic quantities taken from the NCEP/NCAR R-1, ERA20C, CIRES20, and CMIP5 data are used to initialize four more sets of WRF simulations. There is no significant variation in TC size nor intensity over the WNP within the past 90 years based on the idealized downscaling high-resolution WRF model, whereas those simulations initialized based on CMIP5 data show that both the TC size and intensity would increase in the future (2071–2100) of the representative concentration pathway 8.5 (RCP8.5) as compared to those during the current (2010–2040) climate stage of RCP8.5. An explanation for these findings is given by referring to impact of the air–sea thermal disequilibrium and acutely increasing temperature in the TC outflow, while their relation to previous works is also discussed.