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The Future … One More Time

Rob Pinkel*


In discussing visions of the future, it is important to distinguish between what one desires to happen and what one predicts will probably happen. I’ll attempt to focus on the former.

The process of “planning for 2025” is now entering its second decade. In the years remaining, there is sufficient time to spin up one new Tropical Ocean-Global Atmosphere (TOGA) or WOCE sized research program, but not two. With the OOI spinning up over the next five years, there is no dominant vision for the next new research thrust.

In terms of changing science, I am most aware of developments near my own field of interest. Presently, there is a growing appreciation that the mesoscale and larger currents loose energy and mix scalars at rates that only partially depend on their own flow properties. Sites of high turbulent mixing are found near topography that is tuned to the baroclinic tides and also near flow structures that can refractively trap near inertial waves. The space-time geography of these mixing sites can be inferred from relatively few key process-experiments. Does an “eddy viscosity” fueled by breaking internal waves indeed extract energy from the mesoscale as would a true viscosity? In the atmosphere, low-latitude waves are thought to drive eastward flow at mid-latitudes. Ideally, the numerical models of 2025 will have a dissipative scheme that incorporates external geographic-fortnightly modulated mixing and the refractive trapping of

*

Scripps Institution of Oceanography, University of California, San Diego

Using the FOFC fleet renewal plan as a starting point.



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The Future . . . One More Time Rob Pinkel* In discussing visions of the future, it is important to distinguish between what one desires to happen and what one predicts will probably happen. I’ll attempt to focus on the former. The process of “planning for 2025” is now entering its second decade.† In the years remaining, there is sufficient time to spin up one new Tropical Ocean-Global Atmosphere (TOGA) or WOCE sized research program, but not two. With the OOI spinning up over the next five years, there is no dominant vision for the next new research thrust. In terms of changing science, I am most aware of developments near my own field of interest. Presently, there is a growing appreciation that the mesoscale and larger currents loose energy and mix scalars at rates that only partially depend on their own flow properties. Sites of high tur- bulent mixing are found near topography that is tuned to the baroclinic tides and also near flow structures that can refractively trap near inertial waves. The space-time geography of these mixing sites can be inferred from relatively few key process-experiments. Does an “eddy viscosity” fueled by breaking internal waves indeed extract energy from the meso- scale as would a true viscosity? In the atmosphere, low-latitude waves are thought to drive eastward flow at mid-latitudes. Ideally, the numerical models of 2025 will have a dissipative scheme that incorporates external geographic-fortnightly modulated mixing and the refractive trapping of * Scripps Institution of Oceanography, University of California, San Diego † Using the FOFC fleet renewal plan as a starting point. 55

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5 OCEANOGRAPHY IN 2025 inertial waves. Field experiments to support this modeling effort will be great fun. In terms of ship usage, numerous enhancements of scientific capa- bility are possible. High-frequency (~50 kHz) multibeam swath sonars should be installed on research vessels and used for the routine mapping of scattering layers in the upper 600 m of the ocean. On a moving ship, a swath sonar provides a 3D view of plankton patchiness that can be recorded whenever the ship is underway (Figure 1). The midwater zoo- plankton community is relatively inaccessible to net sampling. Acoustic surveying can help to focus in situ sampling campaign. The lateral slope of plankton layers is a measure of isopycnal slope, a quantity of direct interest to physical oceanographers. The recent development of seismic refractive imaging of deep ocean density structures should be exploited. A wealth of information can be derived from ship-mounted Coastal Ocean Pinkel_Figs_ShipSurvey Schematic_08.eps FIGURE 1 Schematic of a survey where the ship (arrow) is using multibeam so- nar to map zooplankton layering in the water column, assisted by a constellation of AUVs and all operating within an acoustic tomographic array.

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5 ROB PINKEL Dynamics Applications Radar (CODAR). By steaming repeatedly around a fixed path, tidal and inertial currents can be separated from sub-inertial signals. Pooled AUV resources should be expanded, such that a ship user has the ability to operate a small constellation of remote sampling platforms. A central survey ship and surrounding AUVs could conduct small scale tracer release experiments, frontal studies, etc., with great efficiency. The development of low-speed long-range gliders has radically improved existing observational capability. The three present versions are all varia- tions on the “virtual mooring” theme. In terms of platform capability, huge range of parameter space remains to be explored. Larger gliders/ AUVs can carry more energy relative to their drag. By 2025 one hopes that an assortment of designs are available, each excelling at a different task. In the present community, the operators of pooled AUVs/ROVs also carry on platform development, in an ongoing response to customer demand. This has the inadvertent side effect of killing the development of alterna- tive systems by independent PIs at “non-subsidized” sites. The surviving AUV/ROV development groups in the U.S. are each associated with a source of “fenced” financial support. A way must be found to “broaden the gene pool” while still pooling the hardware. Incremental technical advances in selected areas can lead to greatly expanded scientific capabilities. Development of extremely low-powered versions of basic sensors such as current meters and CTDs will enable much broader bandwidth experiments. The creation of improved batter- ies will contribute to this bandwidth increase. A significant increase in the veracity of commonly used sensors is also required. Since 1995 (t0–15 years), there has been relatively little progress. A next-generation family of standard tools should be deployed by 2025 (t0+15 years). A focused program by NSF and/or ONR in this area would be catalytic. Data transmission on global scales is presently accomplished by Irid- ium. The cost per bit must be enormously reduced if Iridium is going to serve as the primary remote data-link for the community. A transforma- tive development would be the creation of planar phased-array antennas that would enable HiSeasNet broadband communications using relatively small surface buoys. Modularized solar power/battery storage systems and HiSeasNet antennas/servers should be developed and managed as a pooled resource.