Modified Leith viscosity formula in hor_visc

[herrwang0]

It looks like part of the modified Leith viscosity formula is a bit different from the literatures (and the description at the end of this module).

MOM6/src/parameterizations/lateral/MOM_hor_visc.F90

Line 935 in 688bff9

vert_vort_mag(i,j) = grad_vort_mag_h(i,j) + grad_div_mag_h(i,j)

MOM6/src/parameterizations/lateral/MOM_hor_visc.F90

Lines 2839 to 2840 in 688bff9

	!! - A dynamic Leith viscosity, \f$\kappa_{Lth}(x,y,t) =
	!! C_{Lth} \Delta^3 \sqrt{|\nabla \zeta|^2 + |\nabla \dot{e}_D|^2}\f$.