Extra-tropical ocean-atmosphere coupling through moist convection
Lead researcher: Dr Arnaud Czaja
The current generation of climate models highlights the tropics (30S-30N) as the region of the Earth where climate variability is shaped jointly by the ocean and the atmosphere (see El Nino events for example). This two-way interaction is mediated by atmospheric convection (warm and moist air rises while cold dry air descends).
In a recent study (Czaja and Blunt, 2011) we have been investigating whether moist convection could also play a role in ocean-atmosphere coupling away from the Tropics (Fig. 1 - click on the image to the right). As the diagnostic shows, moist convection does indeed occur frequently and reaches deep into the atmosphere, especially over intense currents like the Gulf Stream or the Kuroshio. This is a very exciting result as it might provide a new pathway to communicate oceanic variability, likely more predictable than internal atmospheric variability owing to its slower evolution, to the atmosphere. Interestingly, the mechanisms involved in moist convection in the extra-tropics differ from those in the tropics due to the larger effect of the Coriolis force. More work is needed to incorporate them into coupled climate models.
- Czaja A., and N. Blunt, 2011: A new mechanism for ocean-atmosphere coupling in midlatitudes. Quart. J. Roy. Met. Soc., in press