Oral

IAPSO

JPM03 - Ocean and climate seamless forecasting

Impact of sea surface temperature diurnal amplitude on tropical climate systems

The diurnal variation of sea surface temperature (SST) plays a principal role in air-sea interactions in tropical regions. The diurnal amplitude of SST (DSST) is always underestimated in previous studies due to the coarse vertical resolution. To address this issue, the SST diurnal cycle parameterized by a diagnostic sublayer scheme was incorporated into a climate model named FIO-ESM v2.0. Based on the model, the experiment with a more reasonable diurnal amplitude (DA) in the SST had a better simulation ability for ENSO and the Asian summer monsoon onset (SMO) compared with the experiment with small DA. The interannual variations in DAs lead to spatially inhomogeneous differences in SST anomalies (SSTAs) in the equatorial Pacific between the experiments with large DAs and small DAs. Furthermore, the differences in SSTAs ultimately contribute to more accurate simulations of ENSO characteristics, including amplitudes and phase-locking, in large DAs experiments through air-sea interactions. Moreover, large DAs of SST contributes to surface warming in the Bay of Bengal and changes atmospheric circulation, which finally trigger an earlier SMO. Our findings improve the ability of climate models to simulate more realistic tropical climate systems.