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The Non-Boussinesq ROMS and Its Applications

The Non-Boussinesq ROMS and Its Applications. Y. Tony Song Jet Propulsion Laboratory. Contents: The development of non-Boussinesq ROMS (Hou, Caltech; Colberg, JPL) GRACE, inter-ocean transport (Zlotnicki, JPL; Susanto, Lamont-Doherty)

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The Non-Boussinesq ROMS and Its Applications

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  1. The Non-Boussinesq ROMS and Its Applications Y. Tony Song Jet Propulsion Laboratory • Contents: • The development of non-Boussinesq ROMS (Hou, Caltech; Colberg, JPL) • GRACE, inter-ocean transport (Zlotnicki, JPL; Susanto, Lamont-Doherty) • Coupled earthquake-ROMS for tsunami prediction (Caltech & OSU)

  2. TOPEX/Poseidon Grace Observing Ocean’s Surface & Bottom Launched 2002 Sea Surface Height T/P-Jason provides SSH, representing volume changes (heat expansion), but most ocean models are incompressible. GRACE measures ocean bottom pressure, representing water mass changes, but most models are not mass-conserving or topography-following. Stratified Ocean Ocean Bottom Pressure

  3. ROMS vs non-Boussineq ROMS 1. S-coordinate (Song&Haidvogel 1994): SCRUM/ROMS 2. Sp-coordinate (Song&Hou 2006; Song et al. 2005): Ocean-bottom-pressure model (non-Boussinesq ROMS) Tony Song, January 2006

  4. Non-Boussinesq Global Ocean Model Results • SOI (E---W): Atmospheric pressure Oscillation • Nino3 (E---W): SST Oscillation The strongest OBP signal in the northern hemisphere

  5. GRACE-Observed Ocean Mass Changes Greenland ice melting fast than previous thought Sumatra earthquakes Tony Song, August 2006

  6. Focusing on the North Pacific

  7. ROMS_NB Development • List: • based on recent ROMS • couple sea-ice • couple earthquakes • couple land loading See Frank Colberg’s poster Tony Song, October 2007

  8. JGR-Ocean special section (111, 2006): Dynamic Processes and Circulation in Yellow Sea, East China Sea, and South China Sea Guest editors: Zheng (UM), Fang (FIO) & Song (JPL) • List of Papers for JGR Special Issue • Sea surface temperature variability in the China Seas from 1982 to 2003 • Observations of coastal upwelling in summer 2000 in the northeastern South China Sea • Current measurements and spectral analyses in the Luzon Strait during spring of 2002 • Thermohaline circulation in the Deep South China Sea Basin inferred from oxygen distributions • Measurements of the turbulent energy dissipation rate ε and an evaluation of the dispersion process of the Changjiang Diluted Water in the East China Sea • Numerical simulation of meandering, patch and lens structures of Changjiang Diluted Water in Yellow Sea • Analyses of Upper Layer Thickness Variation in the South China Sea from Satellite Altimeter Data and In-situ Measurements • Estimate Interbasin Transport Using Ocean Bottom Pressure. Part I: Theory and Model for Asian Marginal Seas • Regional Wind and the Lombok Strait Throughflow • Three-dimensional structure of the summertime circulation in the Yellow Sea from a wave-tide-circulation coupled model • Interannual variability of the gap in the Indo-Pacific warm pool over South China Sea associated with ENSO and IOD • Acoustic transmission in the cold eddy in the southern East China Sea • Surface current field and seasonal variability of Kuroshio and adjacent regions derived from satellite-tracked drifter data • Development of Sub-surface Warm Water in East China Sea in Fall • Variation of the Yellow Sea Warm Current and related eddies in winter • Observation of the seasonal evolution of the Yellow Sea Cold Water Mass in 1996 – 1998 • The mechanism of internal waves in the Luzon strait • The development of ocean and ecosystem numerical models and applications to the Southern Yellow Sea • Current structures and their seasonal variation in Huanghai (Yellow) Sea and East China Sea • Response of the South China Sea circulation to El Nino as seen from the variable-grid global ocean model results • The upwelling off Yangtze River estuary and adjacent sea in summer • Interannual variation of the South China Sea surface fields in the recent decade from satellite observations • The upwelling system in the Yellow Sea and East China Sea: Results from Field Observations and Numerical Modeling • The current-vortex structure of the Southern East China Sea in Summer • Winter Fronts in Taiwan Strait • Origin and distribution patterns of Sediments in the Southern Yellow Sea • A numerical study on dynamic mechanisms of seasonal temperature variability in the Yellow Sea • The characteristics of hydrographic and chemical elements of the Yellow Sea and East China Sea in summer, 1998 Tony Song, August 2004

  9. Asian Marginal Seas & Their Connections (Song, JGR-Oceans, 2006) (d) (c) (b) • Inter-basin transport is difficult to estimate because of its: • complex geometry • dependence on local and remote forcing (a) Tony Song, August 2004

  10. Geostrophic and Hydraulic Control (a) Garret & Toulany [1982] gives a simple method to estimate the surface geostrophic transport. (b) Whitehead [1989] gives a simple method to estimate the mean transport (upper bound) by hydraulic control theory. Estimate strait transport by Combining (a) and (b): Tony Song, August 2004

  11. Seasonal Variability Based on SSH only Based on SSH and OBP • Ocean Bottom pressure is necessary for a better estimate of the seasonal inter-basin transports Tony Song, August 2004

  12. Coupled Earthquake-Ocean Model for Tsunami Study Related Work Song et al., The 26 December 2004 tsunami source estimated from satellite radar altimetry and seismic waves, GRL, 32, doi:10.1029/2005GL023683 (2005). Song et al., Horizontal impulses of continental slopes dictate the 26 December tsunami, revised for Ocean Modelling (2007) Song, Y.T., Detecting tsunami genesis and scales directly from coastal GPS stations, GRL, 34, doi:10.1029/2007GL031681 (2007). Song and Han: Satellite observations challenging the long-held tsunami genesis theory, Review in Nature (2007). Tony Song, January 2006

  13. Tsunami and Earthquake History Zhang Heng (張衡, 78 – 139 A.D.) was an astronomer, mathematician, inventor, and poet of the Eastern Han Dynasty in ancient China. Famous for his invention of the first seismograph (132 A.D.) Thucydides (460 – 400 B.C.) was a Greek historian of the Peloponnesian War. Recorded the Aegean Sea tsunami (426 B.C.) Seismometers can detect only earthquakes, but not a tsunami itself, which is dangerous to many coastal communities. When earthquake is coupled with ocean models on modern computers, they are able to provide early warnings for those coastal regions at risk.

  14. 1. Introduction More recent tsunamis: No successful warning so far. State of Hawaii’s estimation: an evacuation from a tsunami alarm in 1996 would have cost the state $58.2 million in economic losses. Since 1982, tsunami warnings based on earthquake magnitude have produced false alarms 16 out of 16 in Pacific (U.S. Government Accountability Office, GAO-06-519). Tony Song, January 2005

  15. 2. Tsunami Prediction System seafloor motions Predict Tsunami Tony Song, January 2006

  16. 3. Tsunami Genesis Theory Song et al. (2007): deriving tsunami-source energy directly from ground motions. Conclusion 1: Earthquake energy ≠ Tsunami energy Conclusion 2: Lateral motions of continental slopes transfer the major tsunami energy Tony Song, January 2006

  17. 4. GPS-Predicted Tsunamis (validated by three historical events) Directly detect the mechanism that generates tsunamis. By-passing the earthquake-magnitude-based method that had often caused false alarms. Tony Song, January 2006

  18. 5. Determine Tsunami Scales • Earthquakes—Richter’s scale (magnitude) • Hurricanes—Simpson’s scale (category) • Tsunamis can be scaled (based on sqrt (ET) ~ tsunami height): • IfST < 5, local warning only. • If ST > 5, basin-wide warnings and modeling are needed. • Early warnings can be issued in 20 minutes after quake. Tony Song, January 2006

  19. 6. Validations (1964 & 2005 Tsunamis) Tony Song, January 2006

  20. 7. Proposed tsunami-detection Plan • Plan3. GPS detection system (~$5 millions) serves two purposes: • Detect tsunami potentials • Monitor plate boundaries Plan1. Satellite-constellations: ~$300 millions (Nobody wands to pay for it) 1,440 GPS stations Plan2. DART buoys: ~$50 millions Pacific only (does not protect people on the coastal side) Tony Song, January 2006

  21. At United Nations Description of Event: JPL’s tsunami prediction concept was selected and reported at UN’s EWC3, Mach 25~30, 2006, Bonn, Germany German newspaper report: “Tension at the border” …Tony Song of NASA broke silence on Tuesday at the international early warning conference in Bonn. Before the event, former US president Bill Clinton and Federal Minister of Foreign Affairs Frank-Walterstone Meier and more than 1000 scientists urged to furnish as fast as possible warning systems for Tsunamis. But now Song demonstrated his colleague that they had not understood the cause of the giant waves correctly. According to the established theory a Tsunami develops, if the sea water gets an impact with a sea-quake transferred by the sea- bottom: The soil moves thereby like a piston perpendicularly upward, it is said. Song meanwhile found out that the Tsunamis was released on 26 December 2004 particularly when lateral breaking the soil….

  22. Summary • The development of non-Boussinesq ROMS has several important applications: • Mass-related ocean climate studies • Geodedic-related applications (earth rotation, GPS, tsunami) • Hydrological applications (ice, land fluxes) • All of these topics are relevant to NASA’s missions. Tony Song, January 2006

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