The new CMCC operational seasonal prediction system

The purpose of this report is to provide information on the new version of the operational CMCC SPS3. 5 Seasonal Prediction System/Model (s) version which will replace in operations the former version SPS3 starting from the operational forecast of October 1st, 2020. The new version differs from the previous one essentially only for the horizontal resolution of the atmospheric model component (CAM 5.3), plus a number of comparatively minor details which will be mentioned below. All hindcasts previously available (1993-2016) have also been rerun, for the same dates, at the new, higher, atmospheric model resolution, all other system characteristics having remained essentially the same.