I need help with the following question about magnetic fields

Although the mechanism is not fully understood, the magnetic field of the Sun is widely accepted as the cause of sunspots and solar flares. This magnetic field, sometimes as strong as 0.47, is created by the convection of plasma under the surface of the Sun. Below is a diagram showing the magnetic field of a sunspot (in dashed lines). magnetic field with trapped plasma T = 5800 K T=4000 K surface S N of the sun convection cells Suppose that the magnetic field of a circular sunspot is created by a thin uniform cylindrical convection layer around the magnetic field (with the axis of cylinder aligned with the magnetic field, which is NOT exactly as shown in this figure). Also suppose that this sunspot has a uniform magnetic field of 0.37 within the convection cylinder and a negligible magnetic field outside of the cylinder. Estimate the surface current density carried by the cylindrical convection flow