quivermc is an adapted version of Andrew Roberts' ncquiverref. Dr. Roberts' function and this function fix a couple of problems with Matlab's quiverm function. The two primary reasons you should never use quiverm are as follows:
1. Matlab's quiverm confoundingly mixes up u and v. By convention in the Earth sciences, u is the zonal component where eastward is positive and v is the meridional component where northward is positive. Matlab gets this wrong, but the quivermc function described here gets it right.
2. For reasons related to ship travel and some old legacy code from Navy guys decades ago, Matlab's quiverm scales vectors in a strange way that depends on latitude. If you're plotting some absolute field like wind vectors, there is no physical reason that you would want to scale vectors in such a way that their zonal components shrink to zero at the poles.
In addition to fixing the problems described above, quivermc also allows a few extra options including color settings, arrow density, and options for displaying converging or diverging flow.