The Equatorial Line Observations Campaign: Physical Oceanography within the Maritime Continent

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The Maritime Continent (MC) is a critical region in the global weather and climate system forcing global atmospheric variability on sub-seasonal to decadal time scales, and is the core region for the Madden-Julian Oscillation (MJO). Nonetheless the multi-scale interactions of the atmosphere, ocean and land surfaces in the MC region are sparsely observed, poorly understood and badly represented in models, leading to large systematic errors in extended range forecasts such as precipitation. Propagation by the MJO eastward through the MC is the least predictable part of the MJO lifecycle. The MC islands create a natural barrier to this propagation by fostering land-air-sea interaction, especially on diurnal time scales. This project is to support the physical oceanography measurements of the MC as part of the interdisciplinary Equatorial Line Observations (ELO) field campaign. The main objective of the ELO field campaign is to use the collected in situ, remotely sensed and state-of-the-art numerical models to characterize diurnal cycles of atmospheric convection and upper ocean temperature during CCKW and MJO propagation across the MC region. An improved understanding of the air-sea interactions in the MC region would result in the advancement of forecasting in a densely populated region (i.e., MC). Improved reliability of weather and climate forecasts will benefit the policymakers, strategic planners, insurance industry and food security industries that use these predictions for decision-making. Collaboration between scientists from the USA, UK and Indonesia will contribute to research diversity and capacity building among all the involved institutions with great benefit for the early career researchers involved in this project. The data and results from ELO will be widely disseminated at conferences, YMC workshops and in publications.The ELO observational network will consist of three land-based and two ocean-based stations along the equator spanning from the eastern Indian Ocean to Sumatra and across the shallow Karimata Strait to Borneo. This experimental design allows for coherent observations of dynamical and thermodynamical properties of the atmosphere and ocean during CCKW and MJO events across the MC. Meteorological and oceanographic instruments will be deployed to measure upper ocean stratification, surface fluxes, precipitation and atmospheric stratification to characterize the coupled air-sea variability in the presence of CCKWs and the MJO. In this physical oceanography component of the project, two moored chains of discrete temperature and salinity sensors will be deployed within the shallow waters of Karimata Strait. The purpose is to study the evolution of the upper ocean warm layer stratification associated with the diurnal convection and its variability. In particular, the team is interested in how the shallow seas in the Karimata Strait might precondition the propagating CCKW and MJO systems before reaching Borneo. They will address the importance of diurnal upper ocean temperature within the warm layer on the evolution (enhancement or decay) of atmospheric convection during its nighttime offshore propagation and in turn the impact of nocturnal precipitation on oceanic barrier layer development and subsequent development of a warm layer in the following days.