Contrasting the Indian and western North Pacific summer monsoons in terms of their intensity of interannual variability and biennial relationship with ENSO

• Main Authors: Baiyang CHEN, Lei WANG, Minmin WU
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2020-09-01
• Series: Atmospheric and Oceanic Science Letters
• Subjects: indian summer monsoon; western north pacific summer monsoon; enso; intensity of interannual variability; monsoon–enso biennial relationship
• Online Access: http://dx.doi.org/10.1080/16742834.2020.1806683

The intensity of interannual variability (IIV) of the monsoon and monsoon–ENSO biennial relationship (MEBR) were examined and compared for both the Indian summer monsoon (ISM) and western North Pacific summer monsoon (WNPSM) during 1958–2018. Covariability of the IIV and MEBR were identified for the two monsoons. When the MEBR was strong (weak), the IIV of the monsoon was observed to be large (small). This rule applied to both the ISM and WNPSM. Out-of-phase relationships were found between the ISM and the WNPSM. When the IIV and MEBR of the ISM were strong (weak), those of the WNPSM tended to be weak (strong). During the period with a stronger (weaker) ENSO–Atlantic coupling after (before) the mid-1980s, the IIV and MEBR of the WNPSM (ISM) were observed to be stronger. The increasing influences from the tropical Atlantic sea surface temperature (SST) may trigger the observed seesaw pattern of the ISM and WNPSM in terms of the IIV and MEBR multidecadal variability. The results imply that tropical Atlantic SST may need to be given more attention and consideration when predicting future monsoon variability of the ISM and WNPSM.