AbstractThe combined effect of the El Niño–Southern Oscillation and Arctic Oscillation (AO) on the variability of boreal winter (December–February) temperature over South Korea is examined at the sub-seasonal time scale using sub-seasonal to seasonal (S2S) hindcast data. Daily hindcast data from the European Centre for Medium-Range Weather Forecasts (ECMWF) database is used. We selected the following six composite cases using a threshold of ± 0.5 for each index: El Niño and positive AO (EP), El Niño and negative AO (EN), La Niña and positive AO (LP), La Niña and negative AO (LN), positive AO only (PA), and negative AO only (NA). Results from reanalysis data suggest the possibility of using these two climate factors as predictors for one-month prediction of South Korea up to four weeks in advance. Thus, we confirmed that the ENSO plays a statistically significant role in strengthening (weakening) the AO influences on the temperature anomalies in the in-phase (out-of-phase). For example, there is a significant increase (decrease) in mean temperature anomalies through positive (negative) GPH anomalies and warm (cold) temperature advection over South Korea in the EP (LN) case. The ECMWF S2S hindcast demonstrated an acceptable ability to reproduce circulation patterns over East Asia up to three weeks in advance, and sufficiently predicted weekly mean temperature anomalies over South Korea in EP, LN, and PA cases.
Some Meteorological Anomalies and their Relationships with Rice Yield for El Niño Years in South Korea