Presenter: Huamin Sun (Institute of Atmospheric Physics,Chinese Academy of Sciences)

Description:
The North Atlantic sea surface temperature (SST) anomalies often display a tripole pattern. Previous studies have analyzed the factors of the formation and maintenance of the North Atlantic tripole SST anomaly pattern. This study investigates the year-to-year change in the intensity of the North Atlantic tripole SST anomaly pattern during boreal spring. It is found that the North Atlantic tripole SST anomaly pattern has a large amplitude in the decaying spring of the tropical Pacific El Niño and La Niña events. Both El Niño and La Niña events and the North Atlantic Oscillation (NAO) can induce large amplitude tripole SST anomalies during boreal spring. When El Niño and La Niña events and the NAO act together, the tripole SST anomalies have a larger amplitude. The development of large amplitude tripole SST anomaly pattern is associated with a similar tripole pattern in surface latent heat flux anomalies, which is attributed to wind speed anomalies in the tropical and mid-latitude regions and to the sea-air humidity difference anomalies in the high-latitude region. Surface sensible heat flux and ocean advection contribute largely to the SST change in the high-latitude region. Surface sensible heat flux and ocean advection have a supplementary effect in the mid-latitude region. The El Niño and La Niña events induced wind and surface heat flux anomalies in preceding winter are mainly in the tropical and mid-latitude regions. The NAO has a larger effect on wind and surface heat flux anomalies in preceding winter in the high-latitude region.