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Scaling properties of the velocity turbulent field from micro-structure profiles in the ocean

VIENNA EGU 2012 APRIL 2012. Scaling properties of the velocity turbulent field from micro-structure profiles in the ocean. Xavier Sanchez Martin Elena Roget Armengol Jesus Planella Morato Physics Department University of Girona. Experimental data: Oceanic profiles

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Scaling properties of the velocity turbulent field from micro-structure profiles in the ocean

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  1. VIENNA EGU 2012 APRIL 2012 Scaling properties of the velocity turbulent field from micro-structure profiles in the ocean Xavier Sanchez Martin Elena Roget Armengol Jesus PlanellaMorato Physics Department University of Girona

  2. Experimental data: Oceanic profiles Cruise: 54N from America to Europe. Ship: AkademikIoffe. P.P. Shirshov Institute of Oceanology. Data: April 1999. Measure instrument: MSS micro-structureprofiler Lozovatsky, I., M. Figueroa, E. Roget, H. J. S. Fernando, and S. Shapovalov, 2005: Observations and scaling of the upper mixed layer in the North Atlantic. Journal of Geophysical Research-Oceans,110 Objectives: Development of a methodology for the determination of the transverse Kolmogorov structure functions (SF) with the spatial series measured with a shear airfoil installed in a free sinking profiler. Comparison of the measured transverse anomalous scaling of the SF (intermittency) in the inertial range (IR) with previous works, with longitudinal and transverse SF. Has the transverse SF a different scaling that the longitudinal? Does the anomalous scaling (intermittence) depend on the Re number?. Or alternatively, is this scaling universal? d) Comparison of the self-scaling or ESS (extended self-similarity) with the direct scaling. Do they fit for high Re number? 1. Scope of the work.

  3. Free sinking MSS Profiler: FROZEN FIELD HYPOTHESIS: 2. Structure functions from oceanic profiles. ENSEMBLE OF OVERLAPPED SEGMENTS: L0 p-orderStructurefunctions:

  4. INERTIAL RANGE SCALING OF THE STRUCTURE FUNCTION: From K41 to the intermittency and the anomalous scaling measures. K41a: Hypothesis of similarity Kolmogorov 1941 (K41) K41c: 4/5th law. Exact relation Negative skewness 3. K41 and the anomalous scaling. Intermittent behavior of the dissipation: Kolmogorov 1962 (K62): Refined similarity hypothesis Anomalous scaling Cascadeα model for εintermittency. Schertzer and Lovejoy, 1987. JGR 92, 9693-9714 Non intermittent K41:

  5. . 4. Second order statistics: spectrum Sanchez, X., E. Roget, J. Planella, and F. Forcat, 2011: Small-Scale Spectrum of a Scalar Field in Water: The Batchelor and Kraichnan Models. J.Phys.Oceanogr., 41.

  6. 5. Measured anomalous scaling. 4/5th law ?

  7. EXAMPLE: VERY HIGH REYNOLDS NUMBER SEGMENT: NON NATURAL PRODUCTION 5. Measured anomalous scaling.

  8. EXAMPLE: VERY HIGH REYNOLDS NUMBER SEGMENT: NON NATURAL PRODUCTION IR to IS: Lohse et al., 1995, Physicalreviewletters 74,10: 5. Measured anomalous scaling. DIRECT SCALING SELF-SCALING: ESS

  9. EXAMPLE: VERY HIGH REYNOLDS NUMBER SEGMENT: NON NATURAL PRODUCTION 5. Measured anomalous scaling. Scaling exponents are very close to previous measures, for direct and ESS scaling. Lozovatsky, I., E. Roget, J. Planella, H. J. S. Fernando, and Z. Liu, 2010: Intermittency of near-bottom turbulence in tidal flow on a shallow shelf. Journal of Geophysical Research-Oceans, 115

  10. EXAMPLE: VERY HIGH REYNOLDS NUMBER SEGMENT: NON NATURAL PRODUCTION Symmetry of the probability for the transverse velocity increments: 5. Measured anomalous scaling.

  11. EXAMPLE: MODERATE REYNOLDS NUMBER SEGMENT WHERE IR AND L ARE NOT DEFINED 5. Measured anomalous scaling.

  12. EXAMPLE: MODERATE REYNOLDS NUMBER SEGMENT WHERE IR AND L ARE NOT DEFINED 5. Measured anomalous scaling. IR AND INTEGRAL SCALE NOT WELL DEFINED SELF SCALING WELL DEFINED

  13. EXAMPLE: MODERATE REYNOLDS NUMBER SEGMENT: natural production 5. Measured anomalous scaling. THE DIRECT SCALING DOES NOT FOLLOW THE CLASSICAL SCALINGS: NOT DEFINED IR. THE ESS SCALING FOLLOWS CLASSICAL SCALING FOR LONGITUDINAL STRUCT. FUNCT.

  14. CONCLUSIONS: Anomalous scaling of the transverse SF has been measured with a profiler in the ocean. It is the first time until our knowledge. Anomalous scaling of the transverse SF in fluid areas with very high Reynolds number give results very similar to some of the previous measures in field and laboratory with longitudinal and transverse measures. It should be tested with more data before a definitive conclusion. The anomalous scaling at relatively low Reynolds number give values of the anomalous scaling from ESS in concordance with previous measures. In this cases, the direct scaling deviates from classical values when the order of p increases. It should be tested with more data. FUTURE RESEARCH: It’s needed to develop methodology to detect segments where the structure functions show a well defined scaling (ESS or direct). Confirm if the intermittency depends on the Reynolds number or on the stratification. The intermittency analysis will be extended to the temperature, salinity, and chlorophyll. 6. Conclusions and future research.

  15. THANKS

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