Winds shift El Nino flavour

摘要

On average, El Nino events have weakened and the centre of maximum sea surface temperature anomalies has shifted to the west over the past two decades. New research suggests that the strengthening of cross-equatorial winds in the eastern Pacific can cause these changes.El Nino events have dramatic impacts on global weather and climate. In 1997/1998, for example, the strongest observed El Nino event resulted in 22,000 fatalities and US$36 billion in economic losses worldwide, including catastrophic flooding in Latin America and California, and widespread drought in Southeast Asia. Such impacts are dependent on the diversity of the spatial structure and amplitude of El Nino, which in recent years have seen a weakening and westward shift of maximum seasurface temperature (SST) anomalies (Fig. 1). However, the physical processes responsible for this change in El Nino diversity have been widely debated. Writing in Nature Climate Change, Shineng Hu and Alexey Fedorov now report that such changes can belinked to a strengthening of cross-equatorial winds in the eastern Pacific, forced both locally and remotely.