What should we add?

GEMPAK provides a JCBN function, so to support the transition to MetPy, it would be good to provide a direct equivalent. The GEMPAK code indicates:

 * This subroutine computes the Jacobian determinant of two scalar	*
 * grids:								*
 *									*
 *     JCBN ( S1, S2 ) = DDX(S1) * DDY(S2) - DDY(S1) * DDX(S2)		*
 *									*
 * Map scale factors are included implicitly.				*

Looks like a pretty easy thing to implement (famous last words!)

Reference

No response