Current prediction skill for the Madden-Julian Oscillation (MJO) is limited, and particularly poor for the initiation phase over the Indian Ocean. The inability of state-of-the-art global models to reproduce the MJO degrades their seasonal to inter-annual prediction and lessens confidence in their ability to project future climate. The overarching goal of DYNAMO is to expedite our understanding of processes key to MJO initiation over the Indian Ocean and to help improve simulation and prediction of the MJO.
The DYNAMO field campaign is proposed as the US component of CINDY2011 (Cooperative Indian Ocean Experiment on Intraseasonal Variability in 2011), an international field program planned for October 2011 - March 2012 in the equatorial central Indian Ocean region. Four countries (Australia, India, Japan, and the US) will participate. This field program is designed to observe the structure and evolution of cloud populations, their interaction with the large-scale environment, and air-sea interaction processes during MJO initiation. An array of three upper-ocean / surface-flux moorings (DYNAMO moorings) will be used to study oceanic processes in the surface mixed layer and the stratified thermocline in the equatorial Indian Ocean and their effects on the initiation and evolution of MJO. The scientific goals are to quantify and understand the dynamics of the preconditioning, evolution, and recovery of the upper ocean as it interacts with MJO events and, thereby, to provide accurate physics to parameterization schemes in numerical models of the MJO. Key upper oceanic processes crucial to the coupling with the MJO include: (1) turbulence heat flux at the base of the surface mixed layer, (2) barrier layer, (3) Wyrtki jet, (4) shallow Seychelles-Chagos Thermocline Ridge, and (5) diurnal variation of surface forcing, mixed layer processes, and turbulence flux. Testable hypotheses for effects of these oceanic processes are identified and will be tackled using 3.5-month continuous observations of the upper ocean processes and turbulence flux across the equatorial Indian Ocean. The mooring array will be deployed in the center of a radar sounding array consisting of two ships and two island stations, representing the core observational components of the DYNAMO/CINDY2011 program. Each mooring will be equipped with meteorological sensors, arrays of CTD sensors, moored microstructure sensors (pods), and ADCPs. Additional arrays of pods will be deployed on three nearby RAMA moorings. Combined with measurements from other atmospheric and oceanic components of DYNAMO, we will develop a detailed reconstruction of the response (recovery) of the surface mixed layer, barrier layer, shallow Seychelles-Chagos thermocline ridge, Wyrtki jet, and equatorial turbulent flux to (from) the MJO.
Intellectual Merit: DYNAMO moorings will provide observations of the ocean barrier layer, upper-ocean mixing and entrainment, air-sea interaction, and overall surface mixed layer processes in the Indian Ocean which are key to the MJO initiation. These observations will be available to modelers, theoreticians, and other observational groups to better understand and predict the tropical climate system. The observations will provide physical insight into the interaction of oceanic processes with the MJO and lead to physics-based parameterizations that will improve MJO prediction skill.
Broader impact: The project will introduce young scientists to complex multi-scale and air-sea interaction problems in the tropical climate system. DYNAMO observations will be used to calibrate and validate satellite retrievals, benefiting their application to much broader areas beyond MJO-related problems. Improved MJO simulation and prediction born from DYNAMO activities will enhance the capacity to deliver prediction and assessment products on intra-seasonal timescales for societal risk management and decision making, and to strengthen confidence in climate simulation and projection.
