Prof. Gualtiero Badin, Institute of Oceanography, University of Hamburg, D

Wed, Feb. 10^th 2016, 3:30 pm

The talk will be based on a paper, now in press in JFM:
arxiv.org/abs/1510.07485

A brief summary: It is now known that the atmosphere and the ocean show a large range of dynamics at scales below the deformation radius, ranging from internal gravity waves to frontogenic processes. Dynamics at these scales are often at O(1) in the Rossby number, making thus classic approximations such as the quasi geostrophic approximation to break down. In this talk I will study the effects of these ageostrophic flows, and in particular of frontogenetic dynamics, in the statistics of geostrophic turbulence. To do so, I will introduce an approximation called surface semi-geostrophy. Results show that this approximation allows for the formation of filaments as well as for a cyclone-anticyclone asymmetry.