1 / 17

Mechanisms of ocean-atmosphere interactions

Mechanisms of ocean-atmosphere interactions. Arnaud Czaja SPAT PG lecture Nov. 2011. Atmosphere “feels” the ocean through:. Momentum exchanges (friction) Surface heat exchanges. Q. atmosphere. T o. ocean. Atmosphere “feels” the ocean through:. Momentum exchanges Surface heat exchange.

sirvat
Télécharger la présentation

Mechanisms of ocean-atmosphere interactions

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. Mechanisms of ocean-atmosphere interactions Arnaud Czaja SPAT PG lecture Nov. 2011

  2. Atmosphere “feels” the ocean through: • Momentum exchanges (friction) • Surface heat exchanges Q atmosphere To ocean

  3. Atmosphere “feels” the ocean through: • Momentum exchanges • Surface heat exchange Q Radiative + “sensible” + “latent” atmosphere To ocean

  4. Ocean – atmosphere heat exchange • Radiative = solar (up and down) and longwave (up and down). Weakly dependent upon To and hence upon ocean currents, thermocline depth, etc. • Sensible & latent: bring the surface atmosphere into thermodynamic equilibrium with the ocean (Ta=To and RH = 100%). Very strongly dependent upon To.

  5. Sensible heat flux climatology (Wm-2) Annual mean DJF JJA

  6. Latent heat flux climatology (Wm-2) Annual mean DJF JJA

  7. Net heat flux climatology (Wm-2) Annual mean DJF JJA

  8. Over which atmospheric layer is Q=Qlat+Qsen felt? • For given To, destabilize atm by advecting an unbalanced air mass Buoyancy of free atm (bf) advection Buoyancy of atm affected by Q(bs) Ta, qa Q To

  9. Over which atmospheric layer is Qlat+Qsen felt? • At same To, could observe very different atmospheric responses Situation when bs ≈bo << bf advection Ta, qa Shallow perturbation To

  10. Over which atmospheric layer is Qlat+Qsen felt? • At same To, could observe very different atmospheric responses Situation when bs ≈ bo ≈ bf Deep perturbation advection Ta, qa To

  11. Atm. heating rate climatology (K/day) Annual mean DJF JJA

  12. Global Infrared image

  13. Response of the atmosphere to a prescribed heating / cooling • Linear calculations on the board • Follows the classic paper by Hoskins and Karoly (J. Atm. Sci., 1981)

  14. “Gill’s response” to heating (1980)

  15. Relevance of Hoskins/Karoly? • Tropics: condensational heating occurs in cloud clusters and is balanced partly by upward motion in clouds and radiative cooling in the subsiding air in between clouds  hard to know what to choose for Q!

  16. Relevance of Hoskins/Karoly? • Midlatitudes: does not take into account the weather (travelling baroclinic waves)...

  17. Friday session...

More Related