1 / 20

Hyodae Seo, Art Miller and John Roads Scripps Institution of Oceanography

Modeling of Regional Ocean-Atmosphere Feedback in the Eastern Equatorial Pacific; Tropical Instability Waves. Hyodae Seo, Art Miller and John Roads Scripps Institution of Oceanography. Annual AMS Meeting February 2, 2006. Outline. Introduce the regional coupled model

amelia
Télécharger la présentation

Hyodae Seo, Art Miller and John Roads Scripps Institution of Oceanography

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Modeling of Regional Ocean-Atmosphere Feedback in the Eastern Equatorial Pacific;Tropical Instability Waves Hyodae Seo, Art Miller and John Roads Scripps Institution of Oceanography Annual AMS Meeting February 2, 2006

  2. Outline • Introduce the regional coupled model • Discuss the stability adjustment of the atmospheric boundary layer (ABL) due to undulating SST front by TIWs.  Altering heat flux  Coupling with wind stress • Work in progress and summary

  3. Regional coupled model

  4. Boundary Layer Variables Regional Spectral Model (RSM) Regional Ocean Modeling System (ROMS) Bulk Formula or RSM BL Physics SST Lateral BC: Ocean Analysis (JPL/ECCO) or Climatology IC and Lateral BC: NCEP/DOE Reanalysis Scripps Coupled Ocean-Atmosphere Regional (SCOAR) Model SCOAR Model • Purpose: Investigate the air-sea coupling process of ocean eddy scale • Bulk formula or non-local RSM physics in the ABL Atmosphere Ocean • Wind relative to ocean current Seo, Miller and Roads (submitted to J. Climate, 2005) • Sequential coupling

  5. Regional Coupled Model (2)  It is being used to investigate the importance in ocean mesoscale to the tropical Atlantic climate. Here is an example... L: 1 ROMS + 1 RSM H: 1/4 ROMS + 1 RSM Western Africa S. America • TIWs contribute to heat balance in the mixed layer and thus meridional SST gradient, to which the ITCZ is sensitive. • Hypothesis: Resolvingoceanic mesoscale feature such as TIWs and details of coastal upwelling will improve the simulation of SST and marine ITCZ in the Tropical Atlantic.

  6. Regional Coupled Model (3) Central America: Gap Winds, Costa Rica Dome, and ITCZ (Xie et al., 2005)  It is also being used in various regions from the tropics to high-latitude oceans for various purposes. Tehuantepec Papagayo US. West coast : SST-induced Ekman Pumping (Chelton et al., 2006) Bering Sea: Sea-Ice-Atmosphere Coupling Russia C. Mendocino Alaska Bering Sea Pt. Conception

  7. Eastern equatorial Pacific domain;Review of ocean-atmoshere system Evolving SST and wind-stress vector in 1999-2000 45 km ROMS + 50 km RSM • Coupled system • ITCZ / Eastern Pacific Warm Pool • Cross-equatorial trade winds • Gap Winds • Tropical Depressions and Hurricanes • Coastal Upwelling and Equatorial front • Tropical Instability Waves Tehuantepec Papagayo

  8. Changes in stability of ABLdue to evolving SST

  9. Modeled stability changes in ABL due to SST 17(15) warm(cold) phases during 2-4 Sep. 1999 Atmospheric Temperature Virtual Potential Temperature Stronger stratification Weaker stratification Ocean Temperature Zonal Wind Stronger shear Weaker shear

  10. Temporal and spatial associations: Combined EOFs of SST and wind stress CEOF 1 of SST and WS Vector CEOF 1 of SST and WS PC 1 • Warm (Cold) SST enhances (reduces) surface winds; in-phase relationship; • So.. what’s the implication? 1999

  11. Modification of heat flux

  12. Modeled changes in heat flux due to SST CEOF1 of SST & CIWV (kg/m2) CEOF 1 of SST & LH Principal Component 1 kg/m2 • Heat flux suppresses the the growth of TIWs; both turbulent flux and radiative flux provide negative feedback to SST by TIWs. • Observations suggest cooling of ~0.6°C / month from Deser et al. (1993), and Zhang and McPhaden (1995).

  13. Coupling of SST and wind stress and synchronous westward propagation

  14. Coupling of wind stress and SST  ∆  MODEL Observations WSD WSC Chelton, 2005  WSD ~ Downwind SST gradient  WSC ~ Crosswind SST gradient

  15. Westward Propagation in the model SST and Wind stress from July-December, 1999 from model along 2°N WS & SST WSD & DdT SST WSC & CdT • Co-propagation of SST and wind stress • Weaker coupling coefficient in the model than in the observations (e.g. Chelton et al., 2001) WSD & DdT WSC & CdT 4S-4N, 130W-90W

  16. Work in progress • Intensity of wind stress derivatives and its co-propagation with SST gradient suggest that there must be a dynamic feedback from the perturbations wind stress derivatives to energetics and dynamics to TIWs. The nature of this feedback still remains uncertain. • Impact of such additional feedback from the perturbed thermal and dynamic forcing from the atmosphere back on the amplitude and wavenumber-frequency characteristics of the TIWs.

  17. Summary • A high-resolution coupled model has been developed and used in the various regions. • Main purpose is to investigate the ocean-atmosphere feedback on ocean mesoscale spatial and time scales. • Evolving SST front perturbed by the TIWs alters vertical stratification of ABL.  This leads to responses from ...  the turbulent and radiative (implied from the model) heat flux, thus changing thermal component of the atmospheric forcing; anegative feedback.  wind stress and its derivative fields, thus induces dynamic feedback from the atmosphere forcing; This feedback effect still remains uncertain.

  18. Comments or questions?Thanks!

  19. Dependence of wind stress derivatives on the alignment  WSD ~ Downwind SST gradient è  WSC ~ Crosswind SST gradient è Observations Model WSD & Angle WSD & Angle WSC & Angle WSC & Angle

  20. Air-sea coupling in California coastal ocean Over Cold Filaments: 5 days Over Warm Eddies: ~ 100km, 4 months Mean SST & WS WSC SST & WS WSC WSD LH WSD LH • Similar coupling of SST with dynamics and thermodynamics of ABL is also seen in CCS region over various spatial and temporal scales.

More Related