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Potsdam

Potsdam. Damping effect of mesoscale air-sea interaction on Sea Surface Temperature anomaly: a study over North Sea using a high resolution coupled model --- Hu Yang, Jian Su, Alberto Elizalde, Thomas Pohlmann. Introduction. North part influenced more by the Atlantic Water

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Potsdam

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  1. Potsdam Damping effect of mesoscale air-sea interaction on Sea Surface Temperature anomaly: a study over North Sea using a high resolution coupled model--- Hu Yang, Jian Su, Alberto Elizalde, Thomas Pohlmann

  2. Introduction North part influenced more by the Atlantic Water South coast influenced more by the local atmosphere forcing. SST gradient is large.

  3. Coupler:OASIS Wind Pr-Ev Heat SLP SST Oce：HAMSOM Atm：REMO Model configuration

  4. Model configuration Couple time step：1 hour Lateral boundary: IPCC-A1B scenarios run from global coupled ECHAM5 & MPIOM Warm start Uncoupled Cold start 2004 2001 2010 Data analysis periods: 2006-2010 Coupled

  5. Model result Spatial SST anomaly (SSTA)

  6. Model result Spatial surface heat flux anomaly in Feb & Aug Positive downward

  7. Model result Spatial surface heat flux anomaly in Feb & Aug Positive downward

  8. Surface latent heat, sensible heat and longwave radiation have damping effect on SSTA. Damping effect is larger in winter than summer.Spatial latent heat flux anomaly contribute most of the damping effect, is about 61.45%. Sensible heat flux and longwave radiation anomaly have equivalent contributions, is about 17.60% and 20.95% . Model result

  9. Qnet: surface heat flux (positive downward)SSTA: spatial SST anomalyDaily interval data from 2006-2010. Model result Correlation between dSST and Qnet

  10. Model result Spatial SAT-SST, qa-qs, wind speed anomaly. Bulk Formula : sea surface wind speed : sea surface specific humidty : sea surface saturation humidity

  11. Physical explaination SST SAT, Humidity SAT-SST Convection Wind speed qa-qs Evaporation Heat flux < > > < > < SAT-SST Convection Wind speed qa-qs Evaporation Heat flux

  12. Model result Impactof SSTA on surface heat flux anomaly Damping effect exist along the whole year. The modification of SSTA to heat flux is strong. The spatial surface heat budget (also heat content and SST) will be changed.

  13. Conclusion • On temporal scale, SST is forced by Qnet. On spatial scale, SST is forcing Qnet. • Mesoscale air-sea interaction has damping effect on SSTA. This damping effect is missing/weaker in the uncoupled model. • Damping effect is mainly caused by the air-sea temperature and humidity difference induced by large SST gradient. • We suggest high resolution coupled model is needed to study the climate change in the North Sea.

  14. Thanks for your attention!

  15. Linearized the bulk formula

  16. Surface heat flux anomaly determined mainly by the air-sea temperature and humidity difference anomaly.

  17. Uncoupled—(SST prescribed) Coupled Uncoupled—(SST in HAMSOM) Damping effect exist in the whole year. Surface heat flux is modified by the prescribed SST. Uncoupled simulation result varies with different prescribed SST.

  18. The correlation (color) between SST and neutral 10m wind speed. (Small, 2008)

  19. Introduction Recently, observations over strong SST gradient show positive correlation between wind speed and SST. The effectsof SST-inducedsurface wind speedanddirectiongradients on midlatitudesurfacevorticityanddivergence. (O’Neillet al. 2010)

  20. Model result Spatial SST-SAT, Qs-Qa, wind speed, cloud cover anomaly.

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