The change of Southern Hemisphere extratropical cyclone precipitation characteristics in SSP5-8.5 scenario in CMIP6 models

Extratropical cyclone (EC) is the main source of precipitation at midlatitudes, but its precipitation characteristics change with warming still remains uncertain. Here, using 17 CMIP6 models, ECs in DJF in the Southern Hemisphere are tracked and recorded with concomitant sea level pressure and surface temperatures. EC total precipitation change with warming is decomposed into the contribution from EC number, life duration and precipitation intensity. It is found that decreasing EC total precipitation is strongly related to decreased EC number, with life duration contributing about 1/6 that of EC number change. Increasing EC precipitation intensity offsets the decrease due to EC number. To better quantify EC precipitation intensity change with warming, we employ temperature experienced by ECs instead of regional averaged temperature. A higher precipitation increasing rate per degree of warming (6.05%/K) than previous studies was noted because ECs tend to shift poleward with warming. Furthermore, the noted rate is mainly related to the increase of near-surface temperature (62%), followed by increased EC intensity (23%).