Canonical correlation analysis (CCA), a linear statistical method designed to find correlated patterns between predictor and predictand fields, is applied to the eastern Asian region of Korea and Japan. The cross-validation technique is used to estimate the levels and sources of forecast skill for 3-month-averaged surface air temperature and total precipitation for the 37-yr time period of 1961–97. Quasi-global SST, Northern Hemisphere 700-hPa height, and prior values of the predictand field itself are used as predictor fields in an attempt to maximize the strength of the predictive relationships. The global SST field turns out generally to contribute the most to the final skill, with the exception of the winter season, in which the geopotential height field contributes most. The highest skill for temperature forecasts occurs in early spring, with relative insensitivity to the forecast lead time. This skill is statistically significant, averaging over 0.3 but including higher values locally. A se... Abstract Canonical correlation analysis (CCA), a linear statistical method designed to find correlated patterns between predictor and predictand fields, is applied to the eastern Asian region of Korea and Japan. The cross-validation technique is used to estimate the levels and sources of forecast skill for 3-month-averaged surface air temperature and total precipitation for the 37-yr time period of 1961–97. Quasi-global SST, Northern Hemisphere 700-hPa height, and prior values of the predictand field itself are used as predictor fields in an attempt to maximize the strength of the predictive relationships. The global SST field turns out generally to contribute the most to the final skill, with the exception of the winter season, in which the geopotential height field contributes most. The highest skill for temperature forecasts occurs in early spring, with relative insensitivity to the forecast lead time. This skill is statistically significant, averaging over 0.3 but including higher values locally. A se...

We investigated interdecadal relationship changes between the Arctic oscillation (AO) and Aleutian low (AL) for the period 1980–2021 along with the linkage on surface air temperature (SAT) over Eastern Eurasia during the boreal winter (December–January–February). The AO–AL relationship has weakened since the mid‐1990s. To explore a possible explanation, we compared atmospheric fields for two contrasting periods, one when the AO–AL relationship is the strongest (1986–2006) and one when it is the weakest (2000–2020). In both periods, atmospheric circulation over the Arctic region for the two AO–AL in‐phase relationships (i.e., either +AO/+AL or –AO/−AL) evolves with negative AO‐like patterns, contributing to a weakening AO–AL relationship in concurrent with a cool SAT in Eastern Eurasia. We found that the correlation between AL and SAT over Eastern Eurasia decreases, while the AO and SAT correlation remains unchanged. This implies that low‐frequency atmospheric circulation changes such as those of the AO and AL should be considered when studying SAT changes in Eastern Eurasia.