第七届青年地学论坛

Conventionally, the Indian Summer Monsoon rainfall (ISMR) is affected by warmer- or colder-than-normal sea surface temperature anomalies in the central-eastern Pacific, known as the El Niño or La Niña phenomenon, respectively. Thus, a negative relationship exists between the Indian Summer Monsoon rainfall and El Niño–Southern Oscillation (ENSO). Records show that the relationship weakened after 1980, which affected the prediction of Indian Summer Monsoon rainfall. However， we found that the relationship between the ISMR and ENSO has recovered since 2001. The relationship strength is closely related to the summer tropical Indian Ocean (TIO) sea surface temperature (SST) anomaly, with the TIO warming (cooling) indicating a stronger (weaker) relationship. Under the same El Niño/La Niña scenario, different signs of the TIO anomaly indicate distinct atmospheric circulation anomalies over the Indian Ocean, thus affecting the ISMR–ENSO relationship. The TIO anomaly is principally associated with different types of ENSO temporal development. Strong El Niño events with an early onset, and the transition of El Niño to La Niña, tend to have a warmer TIO and a stronger ISMR–ENSO relationship, in contrast to most of the cases of a decaying La Niña or a La Niña that persists throughout the year. The result brings prospect for improving the ISMR prediction.
 

Indian Summer Monsoon Rainfall；ENSO；Recover；,Indian Ocean basin-wide SST anomaly