Controls on upper ocean processes that impact intraseasonal variability in the Maritime Continent Region

Multi-scale interactions in the coupled ocean/atmosphere of the tropics play a crucial role in shaping the climate state and its spatial and temporal variability. On intraseasonal time scales (20-120 days) the Madden-Julian Oscillation (MJO) is the major player in affecting local and far-field conditions. Operational forecasts of the MJO show a significant reduction in skill as MJO events propagate over the the Maritime Continent, the so-called Maritime Continent MJO prediction barrier.
Recognizing the importance of the Maritime Continent, the international project the Years of the Maritime Continent (YMC, July 2017 – July 2019) has as a major goal the improvement of the understanding and prediction of the MJO as it interacts with the Maritime Continent through an intensive field campaign and associated modeling studies.
The present proposal focuses on identifying the major factors controlling the sea surface temperature, SST, in the Maritime Continent region. Variability of SST on intraseasonal to seasonal timescales strongly influences the maintenance and propagation of the MJO in the region with potential feedbacks between the atmosphere and ocean. In order to make a fair assessment of the role of the ocean in the maintenance and propagation of MJOs over the Maritime Continent in coupled models it is necessary to determine how well the ocean component of the coupled system is capturing the ocean state.
A combination of observations and models will be used to determine the physical processes that influence the response of the upper ocean and SST to intraseasonal to seasonal variability of the atmosphere in the Maritime Continent region. A major focus will be salinity, its influence on the stratification of the upper ocean and associated warming of the surface ocean. The factors influencing the presence of fresh surface layers, their temporal and spatial scales, and impact on SST will be ascertained. We will also determine what it takes for a model to capture their impact properly. The results will be used as a guide to improve ocean/atmosphere interactions in coupled models.
The potential of improving the simulation and prediction of MJO in models, with focus on the Maritime Continent region, and the associated societal benefits, underlie the goals of this proposal. As such the proposal is directly related to the aims of the NOAA CVP program – Observing and understanding processes of intraseasonal oscillations in the Marine Continent Region. Improving the present day MJO in models also applies to assessing the changes to MJO activity, and its impact on the monsoons and tropical cyclones, brought about by climate change. The proposal, therefore is also aligned with the climate objectives outlined in NOAA’s Next Generation Strategic Plan (NGSP, 2010), namely: Improved scientific understanding of the changing climate system and its impacts.