A note on new indices for the equatorial Indian Ocean oscillation

Journal of Earth system science

P A Francis1²  Sulochana Gadgil2¹ 

[1] Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012, India.$$;Indian National Centre for Ocean Information Services, Ministry of Earth Sciences, Hyderabad 500 090, India.$$

关键词: Indian summer monsoon variability;    equatorial Indian Ocean oscillation;    Indian Ocean dipole;    El Niño and southern oscillation.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

It is now well known that there is a strong association of the extremes of the Indian summer monsoon rainfall (ISMR) with the El Niño and southern oscillation (ENSO) and the Equatorial Indian Ocean Oscillation (EQUINOO), later being an east–west oscillation in convection anomaly over the equatorial Indian Ocean. So far, the index used for EQUINOO is EQWIN, which is based on the surface zonal wind over the central equatorial Indian Ocean. Since the most important attribute of EQUINOO is the oscillation in convection/precipitation, we believe that the indices based on convection or precipitation would be more appropriate. Continuous and reliable data on outgoing longwave radiation (OLR), and satellite derived precipitation are now available from 1979 onwards. Hence, in this paper, we introduce new indices for EQUINOO, based on the difference in the anomaly of OLR/precipitation between eastern and western parts of the equatorial Indian Ocean. We show that the strong association of extremes of the Indian summer monsoon with ENSO and EQUINOO is also seen when the new indices are used to represent EQUINOO.

【 授权许可】

Unknown