Influence of spectral cumulus parameterization in simulating global tropical cyclone activity

Abstract:

The influence of a new developed spectral cumulus parameterization (spectral scheme, Baba 2019) in simulating global tropical cyclone (TC) activity was investigated using an AGCM. Experiments were performed using an AGCM and two different convection schemes, i.e., the original convection scheme of the AGCM (Emanuel scheme) and the spectral scheme. The result showed that the both schemes could capture qualitative features of global TC activity in terms of climatology and variability. However, the spectral scheme simulated TC genesis and track density better than the original convection scheme by improving the cold bias. The spectral scheme also provided better results for TC response to interannual variability, i.e., El Niño Southern Oscillation (ENSO) by suppressing excessive convection response to ENSO. The spectral scheme is capable of simulating the variability of TC genesis related to Madden-Julian Oscillation (MJO), due to its higher fidelity, much better than the original convection scheme. Consequently, the spectral scheme can outperform the original convection scheme in simulating global TC activity from various perspectives, and thus the scheme is expected to be useful for TC prediction and future projections.