Observational Study of the Oceanic Surface Parameters in the Eastern Indian Ocean During Two Contrasting Dipole Years 2005 and 2006

Abstract

The Indian Ocean dipole (IOD) is one of the major interannual climate variation signals in this region through the coupled air–sea interactions. In this letter, the oceanic surface parameters in the eastern Indian Ocean during two consecutive contrasting dipole years 2005 (negative) and 2006 (positive) are examined exclusively from satellite and in situ observations. Results showed that there was sea surface temperature anomaly up to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm 2\ ^{\circ}\hbox{C}$</tex></formula> in the south eastern equatorial Indian Ocean (EEIO) during the mature phase (September–November) of the dipole. Except for the south EEIO, the south of the equator showed very high positive sea level anomaly (up to 45 cm) during the boreal fall (September–November) in 2006 under the influence of the strong positive IOD event. Similar coherent differences were observed in freshwater flux and sea surface salinity anomalies which show the large impact of these dipole events in the south EEIO box. Also, the seasonal rainfall during the northeast Indian monsoon for these two years shows substantial difference over southern India which reveals the paramount impact of IOD on the northeast monsoon rainfall.