Change of the CP ENSO’s role in the occurrence frequency of Arctic daily warming events triggered by Atlantic storms

Abstract

Arctic daily warming is gradually garnering the attention of academics. Here we discuss an interdecadal change around the mid-1980s in the role of the Central Pacific El Niño-Southern Oscillation (CP ENSO) in the occurrence frequency of Arctic daily warming events triggered by Atlantic storms in winter (called the Atlantic pattern-Arctic rapid tropospheric daily warming (A-RTDW) event) and the possible mechanism. Before the mid-1980s, the Central Pacific El Niño/La Niña events weakened/strengthened the Iceland Low (IL); the resulting anomalous northerly/southerly at the east of the IL prevented/favored the A-RTDW event occurrence by leading Atlantic storms away from/into the Arctic. Thus, the CP ENSO could affect the occurrence frequency of A-RTDW events by the CP ENSO/IL teleconnection. In contrast, this role hardly exists after the mid-1980s. Before the mid-1980s, the CP ENSO could affect the polar vortex by planetary wave propagation upwards into the stratosphere to create the CP ENSO/IL teleconnection; thereby, the CP ENSO and A-RTDW could establish a connection. However, after the mid-1980s, the planetary wave associated with CP ENSO could not propagate upwards into the stratosphere; thus, the ENSO/IL teleconnection disappears, resulting in CP ENSO having no effect on the occurrence frequency of A-RTDW events.