The melting of the Greenland ice sheet (GrIS) in summer has rapidly and significantly increased in recent decades, especially for the northern GrIS. Circulation related to GrIS melting is important for understanding the contribution of the GrIS to the global sea level. In this paper, we used the SOM method to obtain three spatial patterns of GrIS melting based on model output data: overall melting, northern melting, and southern melting patterns. We also examined their linkages to the observed atmospheric circulation. GrIS melting is primarily related to Greenland blocking (GB), while different types of GB are responsible for different melting patterns. The overall and northern melting patterns are both associated with high-latitude GB, which is associated with the decay and westward movement of mid-latitude and high-latitude European blocking (EB), respectively. It is found that the generation of mid-latitude and high-latitude EBs are related to mid-latitude eastern North Atlantic warming and Greenland–Norskehavet–North Sea warming, respectively, while the movement of EB is related t upstream weakened zonal wind anomalies. Furthermore, the southern melting pattern is linked to mid-latitude GB, which is associated with the wave train from the East Pacific to Southern Greenland through North America and further related to the mid-latitude of East Pacific warming.

 In recent years, the surface air temperature (SAT) anomalies in winter over North America show a “warm-West/cool-East” (WWCE) dipole pattern. The underlying mechanism of the North American WWCE dipole pattern has been an important research topic. This study examines the physical cause of the WWCE dipole generation.It is found that the positive phase (PNA+) of the Pacific North American (PNA) pattern can lead to the generation of the WWCE SAT dipole. However, the impact of the PNA+ on the WWCE SAT dipole over North America depends on the type of the El Nino SST anomaly. When an Eastern-Pacific (EP) type El Nino occurs, the anticyclonic anomaly center of the PNA+ over the North American continent is displaced eastward near 100°W due to intensified midlatitude westerly winds over North Pacific so that its anticyclonic anomaly dominates the whole North America. In this case, the cyclonic anomaly of the PNA+ almost disappears over the North America. Thus, the WWCE SAT dipole over the North America is weakened. In contrast, when a central-Pacific (CP) type El Nino appears, the anticyclonic anomaly center of the associated PNA+ is located over the North America west coast due to reduced midlatitude westerly winds over North Pacific. As a result, the cyclonic anomaly of the PNA+ can appear over the east United States to result in an intensified WWCE SAT dipole over the North America