Projected changes to the intertropical convergence zone in warming scenario global storm resolving simulations

We investigate the projected changes to the location, width and intensity of the intertropical convergence zone (ITCZ) in two global 30-year coupled storm resolving simulations, evolving under the shared socioeconomic pathway 3.7-0 forcing. The first simulation performed using the storm resolving version of the ICOsahedral Nonhydrostatic model, ICON-Sapphire, resolves convection explicitly and employs a horizontal resolution of 10 km in the atmosphere and 5 km in the ocean. The second simulation performed using the Integrated Forecasting System coupled to the Finite-volumE Sea ice-Ocean Model (IFS-FESOM), utilizes a convective parameterization with reduced cloud base mass flux and has a similar horizontal resolution as the ICON-Sapphire simulation (9 km in the atmosphere and 5 km in the ocean). 

The magnitude of warming over 30 years is about 1K in ICON-Sapphire and 2K in IFS-FESOM. Changes in the seasonal mean ITCZ positions, determined from the latitude of maximum precipitable water in [30°S, 30°N], are not substantial in both the models, except in IFS-FESOM during boreal spring where a southward shift is seen in the Central Pacific basin. Monthly anomalies in the ITCZ latitude also show a southward shift in IFS-FESOM. Trends in the ITCZ width, computed based on the moist margins of the tropics, and ITCZ intensity, determined using precipitation in the ITCZ latitudes, are also analyzed.