Effects of El Niño on spring phenology of the highest mountain in northeast Asia

Twenty-year Normalized Difference Vegetation Index (NDVI) data on the highest mountain in northeast Asia were analyzed to understand their temporal variability and response to large-scale El Nino-Southern Oscillation (ENSO) events. We demonstrated the first unequivocal evidence that El Nino events have played an important role in determining the ecosystem conditions in the Mt. Baekdu area in northeast Asia. The analysis confirmed that the onset of phenological spring was earlier during ENSO years. This was evident from a negative trend of -0.5158 month per ENSO index between year-to-year variations in spring timing and those in ENSO magnitudes. Over two decades, the phenological phases were negatively correlated with air temperature variations under atmospheric warming at Mt. Baekdu. However, such changes in NDVI are not likely to be affected by changes in the local precipitation, as inferred from forest types determined by land cover classification. On the basis of changes in air temperature during ENSO years, the results of this study indicate a significant remote connection between the local ecology at the highest mountain and the large-scale atmospheric and oceanic phenomena.