Interdecadal changes in interannual variability of June temperature over Northeast China induced by decadal shifts in the North Atlantic teleconnection

Summer low-temperature in Northeast China (NEC) could cause local grain reduction. Recent studies have highlighted a notable increase in low-surface air temperature (SAT) events during June in NEC, which diverges significantly from the patterns observed in July, August, and the overall summer average. An analysis of June SAT over NEC from 1961 to 2020 reveals an interdecadal shift around 2003, characterized by decreased periodicity and increased interannual variability. This study investigates the influence of sea surface temperature anomalies (SSTAs) in the North Atlantic during the preceding February on this shift. It is found that the North Atlantic tripole SSTAs (NAT_SST) has a significant impact on June SAT in NEC post-2003. A proposed mechanism is that February NAT_SST can maintain the tripole anomalies into May-June, and inducing SSTAs over the tropical eastern Pacific (SST_EP) after 2003. Both observational and model simulation results support that NAT_SST influences June SAT in NEC through a wave train originating from the North Atlantic, while SST_EP affects SAT in NEC via the Circumglobal teleconnection and British-Baikal corridor-like patterns. The combined effects of May-June NAT_SST and SST_EP resonate to amplify June SAT anomalies over NEC, enhancing both the amplitude of SAT anomalies and interannual variability. Meanwhile, the periodicity of June SAT in NEC shifts to a 2-4 years cycle, aligning with the post-2003 alternation of NAT_SST. This contrasts with the period before 2002, where the relationship between February NAT_SST and May-June SST_EP was inverse, offsets the effects of the two SSTAs.