title: Ocean feedback to pulses of the Madden-Julian Oscillation in the equatorial Indian Ocean.
abstract: Dynamical understanding of the Madden-Julian Oscillation (MJO) has been elusive, and predictive capabilities therefore limited. New measurements of the ocean's response to the intense surface winds and cooling by two successive MJO pulses, separated by several weeks, show persistent ocean currents and subsurface mixing after pulse passage, thereby reducing ocean heat energy available for later pulses by an amount significantly greater than via atmospheric surface cooling alone. This suggests that thermal mixing in the upper ocean from a particular pulse might affect the amplitude of the following pulse. Here we test this hypothesis by comparing 18 pulse pairs, each separated by <55 days, measured over a 33-year period. We find a significant tendency for weak (strong) pulses, associated with low (high) cooling rates, to be followed by stronger (weaker) pulses. We therefore propose that the ocean introduces a memory effect into the MJO, whereby each event is governed in part by the previous event.
authors.affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5503, USA.
authors.forename: James N
authors.initials: JN
authors.lastname: Moum
authors.affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5503, USA.|Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Bandung 40116, Indonesia.
authors.forename: Kandaga
authors.initials: K
authors.lastname: Pujiana
authors.affiliation: Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA.
authors.forename: Ren-Chieh
authors.initials: RC
authors.lastname: Lien
authors.affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5503, USA.
authors.forename: William D
authors.initials: WD
authors.lastname: Smyth