The Pvector is defined by the following equations:
P_{1}=f*[(u*dv/dx)+(v*dv/dy)]
P_{2}=f*[(u*du/dx)+(v*du/dy)]
where the partial derivatives were calculated with the use of the
cdiff function in GrADS.
Note that the Coriolis parameter used here is defined as f=2*Omega*sin(latitude)
and the winds used in the calculation are the observed zonal
and meridional winds and are not geostrophic.
The vectors were made by plotting the vector sum of
P_{1} and P_{2}
and colored by the magnitude of the resulting vector.
Units: m s^{3}
