A Pre-Field Modeling Study of Scales, Variability and Processes in the Near Surface Eastern Equatorial Pacific Ocean in Support of TPOS

We propose a re-examination of the design of a Pacific Upwelling and Mixing Physics (PUMP) process study in light of available observing technologies, by characterizing the space and time scales and dynamics of upwelling and the process-level connection to mixing. We will develop analysis frameworks around testable hypotheses, and determine the sampling requirements for an efficient and robust observational implementation. We will address this objective by exploiting a combination of output from high-resolution ocean and climate model simulations, and existing long-term observations.
To frame our investigation of observing strategies for PUMP, we will address the following scientific questions:
1. What are the dynamics controlling divergence and upwelling?
2. How is upwelling partitioned into adiabatic and diabatic motions?
3. How do the three dimensional meridional circulation cells and their role in the heat budget respond to changes in surface forcing across a range of time scales from synoptic to inter-annual and in different locations within the tropical Pacific?
The proposed effort directly responds to the guiding questions in the solicitation by addressing the following experimental design considerations: What zonal and meridional resolution is needed to adequately measure divergence of mass and the exchange of mass and heat between the thermocline and surface ocean? How long of a deployment of initial observations is needed to adequately represent the statistics of the important processes at play? What regions (e.g. 140ï‚°W or 110ï‚°W) of the eastern tropical Pacific should be most intensively measured? What locations would be most representative of the broader context of the eastern Pacific? Are there locations where available observing technologies are better suited to sample the natural scales of the problem? How far north and south of the equator should the observations extend to capture the key dynamics of the meridional cells? What sustained observations are needed to monitor the state of the vertical exchange in the eastern equatorial Pacific?
A concurrent assessment of the model solutions against currently available long-term observations and select historical process studies will provide an up-to-date understanding of model biases and elucidate the limitations of our recommendations for observing system design. We view the proposed effort as the beginning of an iterative and sustained integration of talents, experience and resources to advance our ability to observe and simulate the tropical Pacific and its impacts on the global climate system, thereby directly aligning with the overall goals of NOAA CVP.