Task: Instance Description Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes the instance 'quasi geostrophic'?

A. Motions describing an equlibrium between pressure gradient force, Coriolis force and the turbulent drag force.
B. A dimensionless number relating the ratio of inertial to Coriolis forces for a given flow of a rotating fluid.
C. Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays.
D. A system or flow that evolves slowly in time compared to the rotation period of the earth, has a length scale of the deformation radius or larger, and undergoes only limited vertical excursions.

Answer: A system or flow that evolves slowly in time compared to the rotation period of the earth, has a length scale of the deformation radius or larger, and undergoes only limited vertical excursions.