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SW06/NLIWI Breakout Sessions

SW06/NLIWI Breakout Sessions. Physical Oceanography January 31, 2007. Acoustics requests from yesterday. Tidal heights - pressure sensors on many devices in array mooring guys could construct surface height field across array - what precision required?

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SW06/NLIWI Breakout Sessions

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  1. SW06/NLIWI Breakout Sessions Physical Oceanography January 31, 2007

  2. Acoustics requests from yesterday • Tidal heights - pressure sensors on many devices in array • mooring guys could construct surface height field across array • - what precision required? • (Wilkin volunteered to assimilate this data into model) • surface waves – Graber • surface roughness variability on NLIW scales? • fcn(winds, NLIW speed) - (Plant/Lyzenga) • front / mesoscale / eddies effects on c(x,y,z,t) • Wilkin / Glenn / Gawark. • NLIW effects on c(x,y,z,t) • Incorporation of multiple analyses with above task + wavefront analysis - not sure who leads this yet?

  3. mooring lines A. Wave Front Analysis PIs: Nash, Duda, Glenn, Plant, Henyey, Moum, Graber • Wave front analysis / arrival times / all platforms (moored/ship/aircraft/gliders) • 2D mapping as a function of time  • Primary objective: to determine mechanisms of ISW generation • Specific goals: • 1. Identify generation sites • 2. Identify generation times • 3. assess geometrical attenuation • Approach: • 1. Perform analysis for one wave • (named waves Rosey(Aug 17,18) /Sonny(Aug19) (Mohsen / Kevin / Aug 9)) • 2. Extend to AWACS period (mesoscale) • 3. Extend to all waves

  4. mooring lines B. c(x,y,z,t) wave fronts (x,y,t) + vertical profile data + currents + modeling: Part I: large scale (Wilkin- all profile data) Part II: NLIW scale (include part A) (PIs: Duda, Nash) - 1st do test wave - then all waves Merged in array

  5. C. Decomposition of current field PIs: Glen, Gawark, Wilkin • Decomposition of current field: • Near-f • Tidal (includes M2 internal tides) • Mesoscale • Q: How do these modulate phasing of tides and NLIW? • Q: How do these affect arrival times at a point? • Q: How are these interpreted in terms of generation mechanisms? • DATA: • Moored data • Codar (array coverage 50% of time – high surface wave periods) • Model data • Ship data – vertical profiles (marginal) • Number of sites with ADCPs? (~12)

  6. C. (cont’d) / Why did largest NLIWs occur in NEAP (not spring) tides? (Both larger and more frequent) • Q: Role of mesoscale in modulating NLIW climate? • DATA: • Mooring SAR ScanFish Glider • Obs. Approach: (identify key frontal sharpness features) • Investigate changes in stratification due to varying runoff and heating over the experimental time period • Use of 2005 data: Thermistor chains and gliders • 2003, 2004 glider data? • Modeling Approach: • Testing Variations in stratifications (N2) against bathymetry, currents with small scale models to see what conditions are required to sharpen the front enough to generate waves • How is amplitude of internal tide affected? PIs: Scott Glenn, Gallacher, Glenn Gawarkiewicz, Wilkin PIs: Alberto Scotti, Gallacher

  7. D. FUNDAMENTAL PROBLEMEnergy Evolution(losses from barotropic tides- global consequence) • Long range propagation: • Turbulence • Upper shear layer and bottom layer • Geometrical spreading (wave front analysis) • Wave-wave interactions • Group/group interactions • Energy interactions • Rotation effects - interactions with pre-existing near-f wave field • Transition from depression to elevation waves • Generation: Energy sources • Steepening of stratification into borelike form • Bore/wave transitions • Solibore propagation vs generation of waves from bore • Modeling (Scotti) PIs: Henyey, Moum, Scotti, Plant PIs: Nash, Henyey, Moum, Scotti

  8. Remote Sensing of NLIW • E. Magnetic anomalies associated to NLIW • NLIW current fields • Walter Podney measured magnetic signatures of waves (Science 20-30 years ago), not from an airplane – tower measurements - used gradiometer • Need data from flights • PIs: Averra / Gallacher • (Moum will provide ADCP data from overflight times) • F. HF Acoustics: remote sensing of + turbulence waves • step 1: Sources of scattering PIs: Lavery/Chu • step 2: Quantification of turbulence PIs: Lavery/Chu/Moum

  9. G. Remote Sensing: Using and Understanding IW Surface Microwave Signatures Plant, Lyzenga, Wackerman, Graber, Williams • Correlations of shipboard and radar ADCP (Endeavor/Oceanus) • ASIS near-surface ADV / radar passes

  10. cusps J. Group/Group Interactions • DATA (sketchy info): • SAR/Endeavor/Oceanus/Moorings • SAR provides long range coverage but does not show evolution • Ships provide detailed but spatially limited anecdotes • Who wins? Who Loses? Is this an energetics issue? • What factors determine this? • What happens at the cusps? • Are lines formed from mutliple point sources? PIs: Graber, Henyey, Moum, Plant, Duda, Nash, Gallacher Daryl Holm / (Holm postdoc)

  11. Models resolve this How to parameterize this? H. Physical structure of waves Q? How can models get turbulent losses / shelf mixing correctly? Define from observations and small scale models. How is this represented by models? Local wave-following LES models, DNS? Small-scale 3-dimensionality of wave fronts (ship board observations) PIs: Scotti, Moum, Henyey, Nash, Graber, Lavery, Chu

  12. K. Variations in waveforms • Under what conditions is each wave form generated? • Objective - predictability • - effects on acoustics • Depression waves at shelf break • Elevation waves at shelf break • Change in sign of depression to elevation waves • Varicose waves • DATA: • moored • ship • Separate issue? - Variations in number of waves and packets PIs – Moum / Henyey / Nash / Scotti / Lyzenga / Plant

  13. Individual PIs Submit some form of documentation of data to Art Newhall?

  14. Remote Sensing: Using and Understanding IW Surface Microwave Signatures Bill Plant, David Lyzenga, Chris Wackerman, Niel Williams, Hans Graber, Ellen Lettvin

  15. Using Microwave Images: Kinematics • Locate IWs – Lettvin, Graber with satellite SAR • Follow IWs as they propagate – Plant from airplane and ship • View crossing or merging IWs – Plant from airplane and ship • Study crest lengths and curvature – Lettvin, Graber with satellite SAR; Plant from aircraft data

  16. Understanding Microwave Imagery • Correlate microwave imagery with surface currents – Lyzenga with ships’ radars; Plant with aircraft and ship data from his radars • Correlate satellite data with ship, aircraft data – Lettvin with input from Plant, Lyzenga • Apply action conservation principles to understand microwave signatures – Lyzenga, Wackerman, Lettvin, Plant • Compare predictions with satellite, aircraft, and ship microwave data – Lyzenga, Wackerman, Lettvin, Plant • Supply wave spectra across IWs for comparison with predictions – Lyzenga from video; Williams from ASIS buoys, WAMOS data

  17. Using Microwave Imagery: Dynamics • Infer subsurface structure from surface microwave signatures of cross section and velocity – All remote sensing PIs: This is the holy grail!

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